A Quantitative Analysis of Axillary Lymph Nodes

A Quantitative Analysis of Axillary Lymph Nodes | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article A Quantitative Analysis of Axillary Lymph Nodes Nicholas A. Robinson, Samuel Ighodaro, Mierra C. Robinson, Casey Thompson, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7366855/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract Background Axillary lymph node dissection (ALND) is common in breast cancer treatment but carries risks like lymphedema. While sentinel lymph node biopsy (SLNB) often reduces the need for ALND, variability in lymph node number and size complicates surgical planning. This study aims to provide more precise data on axillary lymph node quantity and volume to guide surgical decisions and reduce morbidity. Methods Seventy-two embalmed cadavers donated to PCOM Georgia (2019–2023) were dissected to identify axillary lymph nodes using standardized anatomical landmarks. Nodes were tagged, measured, and recorded, with statistical analysis evaluating distribution by region. Results Node counts varied by region, with the pectoral region averaging 5.98 nodes and the humeral region 2.30. Total node volume ranged from 21.1–3770.3 mm³, though most fell within a narrower confidence interval (223.6–372.0 mm³). No significant differences were found by sex or side. Conclusions These findings reveal consistent lymph node counts across sex and laterality but notable regional variability. Narrow volume ranges support more standardized expectations in surgical planning and may improve staging accuracy and lymphedema prognosis. Axilla Lymph Nodes Lymphedema Axillary Lymph Node Biopsy Breast Cancer Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction The lymphatic system comprises a complex network of vessels, nodes, and tissues that eliminates fluid, waste, and protein from the interstitial spaces. Additionally, it serves an immunological role, facilitating the movement of immune cells as they combat pathogens and foreign substances 1 . However, lymph nodes are the most common site of solid tumor metastasis and can contribute to the spread of malignant disease 2 . In treating certain malignancies such as breast cancer, physicians will stage and assess the spread of cancer via the removal and pathological analysis of lymph nodes. This is often accomplished via procedures such as an axillary lymph node dissection (ALND) or a sentinel lymph node biopsy (SLNB) 3 . A lymph node dissection (lymphadenectomy) is a procedure where some or all of the lymph nodes within a region near a malignancy are removed and analyzed for the spread of cancer. An ALND for breast cancer involves an incision across the patient's axilla followed by removal of lymph nodes located lateral to the pectoralis minor muscle (level I) and lymph nodes located directly under the pectoralis minor (level II) 4 . As with other surgical procedures, common complications include pain, surgical site swelling, and infection. Lymphedema is another, often more distressing, complication associated with ALND 5 . Lymphedema is an insufficiency of lymphatic system drainage, which can create issues in fluid and tissue homeostasis 6 . It classically presents as swelling of the affected area, often an extremity, because the fluid and debris in the interstitium cannot fully drain back into the lymphatic system. This fluid accumulation in the tissue may cause additional symptoms, including pain or discomfort, extremity heaviness or fullness, numbness or tingling, fatigue or strength deficits, and reduced motion. If the lymphatic system is insufficient, the buildup of lymphatic fluid causes a chronic inflammatory process, leading to fibrosis, adipose tissue deposition, and thickening of tissues, including surrounding skin 7 , 8 . Historically, many women diagnosed with breast cancer underwent ALND unnecessarily because many or all of their nodes were negative for metastases. Removing many lymph nodes within a region dramatically increases the incidence of complications, especially lymphedema 9 . Performing an SLNB before lymphadenectomy has reduced the incidence of these complications by removing fewer lymph nodes in patients with limited nodal involvement 3 . To perform an SLNB, the sentinel node is identified via tracer dye injected into the primary malignancy. A surgeon will then follow which node(s) take up the dye and remove that node(s). The sample(s) is then sent to a pathologist to analyze for the presence of cancer, and if present, the surgeon will remove more lymph nodes. A negative biopsy result suggests that the cancer has not spread to other organs or the lymphatic system. However, a positive result suggests the malignancy has spread to the sentinel node and possibly to regional nodes or other nearby organs 10 . Sometimes, a patient may still need an ALND 3 . According to the American Society of Breast Surgeons, indications to still perform an ALND if the patient has early-stage breast cancer (T1/T2) include having 3 or more positive lymph nodes on SLNB, palpable biopsy-confirmed axillary lymph node involvement in patients not receiving neoadjuvant chemotherapy, or with persistently palpable axillary lymph nodes after receiving neoadjuvant chemotherapy. Other indications include large or locally advanced breast cancer (T3/T4) or inflammatory breast cancer 11 , 12 . The American College of Surgeons Oncology Group (ACOSOG) Z0011 trial found that patients with T1/T2 tumors who lacked palpable axillary lymphadenopathy could avoid ALND as part of the breast-conserving surgery (BCS) even if sentinel node testing was positive for metastasis. When comparing those who underwent an SLNB to those who had both SLNB and ALND, there was no statistically significant difference regarding local or regional malignancy recurrence rates or the 5-year overall survival rate, further supporting the use of SLNB 13 . Further, there is evidence that there is no difference in survival rate in early-stage breast cancer patients post an SLNB compared to ALND 14 . Lymphedema occurs as a secondary complication in up to 15% of cancer treatments, making cancer treatment the most common cause of lymphedema in developed countries 15 . A previous review found that ALNDs resulted in a 4 times greater incidence of arm lymphedema than an SLNB alone 16 . Yen et al. demonstrated that the removal of 15 nodes compared to the removal of 5 nodes in a lymphadenectomy performed for breast cancer treatment resulted in a tenfold increase in the incidence of lymphedema 17 . McLaughlin et al. found the incidence of patients developing upper extremity lymphedema was 3% (18 out of 600) for those with only a sentinel node biopsy and 27% (91 out of 336) in the patients who underwent sentinel node biopsy and axillary node lymphadenectomy 18 . This data supports that SLNB alone results in fewer patients developing lymphedema than the combination of SLNB and ALND or ALND alone. Unfortunately, since lymph node status is the primary prognostic factor for breast cancer, the ALND has remained a significant determinant for the use of adjuvant therapy despite the high morbidity risk 19 . It is, therefore, beneficial to more precisely determine the minimal number of lymph nodes a physician could remove during an ALND to optimize metastasis diagnosis while minimizing the risk of lymphedema. For example, Peyre et al. found that removing a minimum of 23 regional lymph nodes was required for the maximal survival rate in esophageal cancer patients 20 . Koppie et al. stated that there is no minimum number of lymph nodes a surgeon should remove to maximize survival rates in patients with transitional cell carcinoma, suggesting that the more lymph nodes removed, the higher the survival rate 21 . Currently, ranges for regional and total lymph nodes in the body vary significantly within the axilla, thus making it difficult to recommend an appropriate number of lymph nodes to be removed for any singular patient 22 , 23 . Current data suggests an average of 20 to 30 axillary lymph nodes, although there is significant variation at the individual level 9 . Many previous studies also do not differentiate node size, which can vary greatly, on average between 0.2 and 3.0 mm. The cause of this is still highly disputed. However, some theories include changes due to menstrual cycle patterns or failure of the nodes to divide in utero, leading to larger but fewer lymph nodes in a given region 22 . For those reasons, more accurate data regarding lymph node ranges and averages in the axilla will help healthcare providers decide the risks and benefits of removing additional lymph nodes in the management of metastatic breast malignancies. This data will also allow healthcare providers to more accurately discuss prognosis and risks with their patients before undergoing lymphadenectomies and to set realistic expectations. This study aims to identify more precise axilla lymph node ranges and averages. Materials and Methods Embalming and dissection of cadavers The cadavers utilized for this study were donated to the Georgia Campus of the Philadelphia College of Osteopathic Medicine (PCOM). Dissections were carried out by students from the Doctor of Osteopathic Medicine (DO), Physician Assistant (PA), and Physical Therapy (PT) programs over several academic terms between 2019 and 2023. Prior to the dissections, all students received instruction on the lymphatic system, lymph nodes, and the study's procedures from Dr. Shelley DiCecco, a faculty member in the Physical Therapy Department and the lead investigator. The cadavers were embalmed onsite at PCOM using standardized techniques. The cadavers were initially treated with a solution known as the Maryland State Blend (MSB), produced by Hydrol Chemical Company in Pennsylvania. This solution was specifically tailored to suit Georgia’s environmental conditions. Before injection, the MSB was diluted by adding one gallon of water for every ten ounces of the solution. An initial injection of 4 to 5 gallons was administered over a 2–3 day period for most cadavers. An additional 3 to 4 gallons were then injected until the vascular system reached optimal saturation, as determined by PCOM’s Director of Anatomical Donor Services. For final preparation, the embalmed cadavers were wrapped in cotton soaked in a diluted MSB solution, encased in plastic, and stored in a zipper pouch. They were then placed in a refrigeration unit for approximately 4 to 8 months before being used for dissection. The research team comprised the lead investigator, 12 DO students, and 5 biomedical sciences students. PCOM students typically performed dissections in the afternoons, 4–5 days per week. The lead researchers would follow up on these dissections in the mornings, examining the bodies for lymph nodes in the targeted regions. When a lymph node was identified, it was tagged using a tag gun, and its location and surface area were recorded. The lymph nodes were left intact until the students completed the academic quarter. Researchers regularly revisited the areas to document any newly discovered nodes. At the end of the quarter, the researchers removed all organs, tissues, and nodes to ensure any remaining lymph nodes were identified. The surface area of each node was measured in millimeters using a standard ruler. The size and location of the nodes were documented on a grid during dissections and later transferred to a data spreadsheet for analysis. Cadavers The demographics of the 72 cadavers were 41 female and 31 male, ages 39 to 103 (mean age 73.2 +/- 11.2), with 62 Caucasian, 6 African American, 3 Asian, and 1 of Hispanic ethnicity. The cause of death for each cadaver was unknown during the experiment to prevent bias. The 72 cadavers were examined for paired regions of right and left central, humeral, infraclavicular, parasternal, pectoral, and subscapular lymph nodes. Anatomical landmarks were used to identify each region of nodes. Anatomical landmarks for identifying lymph nodes per region Standard anatomical landmarks were used to identify and distinguish the different lymph node regions. The landmarks used were based on anatomical descriptions from multiple references 22 , 23 , 24 , 25 , 26 . PCOM students conducting the dissections were given a lecture about the research being conducted and the location of the nodes using illustrations of anatomical landmarks. The following are the descriptions given to students, as well as the anatomical landmarks that were used to define the axillary lymph node groups in this study: Central Nodes The central nodes are embedded in fatty tissue at the base of the axilla. They are adjacent to the intercostobrachial nerves, close to the 2nd segment of the axillary artery. Typically, the central nodes are under the fascia and deep to the pec minor. Humeral Nodes Humeral nodes, or lateral nodes, are located along the latissimus dorsi tendon, where it joins the axillary and subscapular veins. These nodes are posterior and medial to the axillary vein on the lateral wall by the medial cutaneous brachial nerve. Infraclavicular Nodes The infraclavicular, or apical, nodes are embedded in the fatty tissue of the clavipectoral triangle, located superior to the 1st intercostal space, at the origin of the serratus anterior muscle. The nodes are located medially to the end segment of the axillary vein and the first segment of the axillary artery. The pectoral major and minor muscles and the associated fascia protect these nodes. A subset of this group, the deltopectoral, consists of 1–2 nodes that can be found below the clavicle between the pec major and deltoid, along the cephalic vein. Parasternal Nodes Parasternal, or internal mammary, nodes are located in the intercostal spaces 1–6, approximately 3 cm from the sternum, near the internal thoracic artery and vein. The transverse thoracic muscle and endothoracic fascia protect these nodes. Pectoral Nodes The pectoral nodes are found on the medial wall of the axilla on top of the muscle belly of the serratus anterior, typically under a thin layer of adipose tissue. The nodes are found between the 2nd, 3rd, 6th, or 7th ribs with the lateral thoracic artery and vein. Frequently, these nodes are found either behind or at the inferior border of the pectoralis minor muscle. A subset, the interpectoral nodes, present 50% of the time, are located at the bifurcation of the thoracoacromial artery between the pectoralis muscles. Subscapular Nodes Subscapular nodes are against the posterior wall of the axilla around the thoracodorsal and subcapular veins. The nodes are divided into 2 groups, with the upper nodes on the inferior portion of the subscapularis muscle and the lower group between the teres minor and latissimus dorsi muscle bellies. There is minimal adipose coverage for the protection of these nodes. Three nerves are also found near the nodes: the thoracodorsal, intercostobrachial, and subscapular. Statistical Analysis Statistical analysis of the recorded data was performed using Excel spreadsheets and SPS Analytics. Cadavers were excluded from analysis if they failed to meet the predetermined lower boundary of one per region. Lower-end ranges from various sources were initially set, yet the study went with “1” to see if these previous studies were accurate in minimal numbers per region 22 , 23 , 24 , 25 . A univariate analysis was performed with data for regions being non-normal. Data analysis indicates non-normal distribution, and each section was confirmed using Q-Q plots. A Wilcoxon Two-Sample non-parametric test was used for comparison with an alpha value of 0.05. Results Table 1 Quantity of axillary lymph nodes broken down by region. mean ± STD Dev Min-Max 95% CI Parasternal 4.36 ± 2.47 0–10 3.90–4.82 Infraclavicular 2.74 ± 1.87 0–9 2.35–3.12 Central 3.32 ± 2.42 0–10 2.90–3.75 Pectoral 5.98 ± 4.15 0–19 5.46–6.49 Subscapular 3.76 ± 2.62 0–11 3.27–4.25 Humeral 2.30 ± 1.31 0–6 1.95–2.66 All quantitative analyses were performed using JMP15 and Excel spreadsheets. Table 1 shows the distribution analysis for each lymph node region within the axilla. Figure 1 is a graphic representation of the quantity of all axillary nodes. A univariate analysis was performed. Analysis of that data was non-normal and confirmed with Q-Q plots. The pectoral region had the greatest range of lymph nodes, with one subject having 19 pectoral lymph nodes. However, the confidence interval for that group remained relatively narrow, from 5.46–6.49. The Humeral region had the smallest range from 0–6 and a narrow confidence interval. Figure 2 is a graphic representation of the total volume of axillary lymph nodes. The overall range was wide from 21.1 to 3770.3 mm 3 . However, a relatively narrow confidence interval (223.6–372.0 mm 3 ) suggests the presence of several outliers with significantly larger volumes. Despite this range, the second largest volume in our data was 1115.8 mm 3 . A Wilcoxon Two-same non-parametric test was used to determine differences in laterality and to compare male and female subjects. Figure 3 is a graphical representation of male vs female axillary lymph node quantities. For this study, the null hypothesis may be rejected if the p-value ≤ 0.05. There was no statistically significant difference (p = 0.13) between the quantity of axillary lymph nodes in males and females. There is also no statistically significant difference (p = 0.27) between axillary lymph node volumes in males and females, as represented by Fig. 4 . Figures 5 and 6 are graphical representations comparing the quantity and volume, respectively, of axillary lymph nodes on the right and left sides. Again, there was no statistically significant difference in quantity (p = 0.58) or volume (p = 0.64) between sides. Table 2 shows the quantity and volume of the total axillary lymph nodes. The 95% confidence interval, total range, average range, and the mean with standard deviation are also reported within this table. Table 3 compares the average ranges of lymph nodes in each anatomical grouping from this study with three previously published sources. Table 4 depicts the average and median lengths for all axillary lymph nodes within each region. Table 2: Total quantity and volume of axillary lymph nodes. mean±STD Dev Avg Range Min-Max 95% CI Axilla Node Quantity 13.69±10.5 12-14 1-50 13-35 Axilla Node Volume (mm 3 ) 297.8±37.1 15780-15786 21.1-3770.3 223.6-372.0 Table 3: Average ranges for each anatomical grouping in this study compared to previous data. Lymph Node Anatomical Grouping Average Range from Current Study Average and Median Range from Földi et al. 22 Standring 23 Zuther 28 Moore 25 Central 2-5 3-6 - - 3-4 Humeral 1-3 - - - 4-6 Infraclavicular 2-4 1-6 or 7-12 - - - Parasternal 4-7 - - 4-6 - Pectoral 4-7 2-6 - - 3-5 Subscapular 2-5 1-8 - - 6-7 Overall Lymph Node Range for Axilla 15-31 10-34 20-30 10-24 4-7 Table 4: Average and median lengths for each axillary lymph node group Lymph Node Anatomical Grouping Average Length (mm) Median Length (mm) Central 4.46 4 Humeral 4.78 4 Infraclavicular 5.63 4 Parasternal 7.24 5 Pectoral 6.92 5 Subscapular 6.79 5 Total Axillary Lymph Nodes 6.19 5 Discussion The study addresses the challenge of balancing accurate cancer staging with minimizing the risk of complications such as lymphedema, a common consequence of lymphadenectomy procedures like axillary lymph node dissection (ALND). The benefits of identifying more precise lymph node ranges in the axilla are clear, as doing so will help guide surgical decision-making in a way that both improves patient outcomes and reduces the morbidity associated with cancer treatment 9 . Further, knowing more precise lymph node ranges may also assist in establishing a prognosis of developing lymphedema for patients who have already undergone SLNB or ALND. For example, one study found that patients undergoing excision of more than 5 lymph nodes are at a significantly increased risk of developing lymphedema 27 . However, if clinicians have a better understanding of differences across patient populations, they may be able to provide a more specific prognosis to their patients. With more precise ranges, clinicians may also be able to provide more informed expectations of improvement with treatment for those already diagnosed with lymphedema. The quantitative analysis of axillary lymph nodes presented in this study provides new insights into axillary lymph nodes' distribution and volumetric variability, which may have implications for clinical decision-making, particularly in surgical planning and oncologic evaluation. Further, this study included a larger sample size with more variety in races and sexes of the subjects compared to previously published data. One of the primary findings is the marked variability in the number of lymph nodes within the pectoral region. Despite one subject having 19 nodes on dissection, the relatively narrow confidence interval (5.46–6.49) suggests that although there is a relatively consistent number of nodes within this region, significant outliers exist, highlighting the need for clinicians to consider potential anatomic outliers. By contrast, the humeral region displayed a smaller range of lymph nodes (0–6) with a similarly narrow confidence interval (1.95–2.66), suggesting less anatomical variability within this region. This distinction may be valuable for guiding clinicians on where to anticipate more significant variability in lymph node distribution within the axilla. However, more studies should be conducted to determine the cause or significance of any variability difference within the regions. When evaluating lymph node volume, these findings indicated a wide range (21.1-3770.3 mm 3 ) with an outlier significantly skewing the upper limit. The narrow confidence interval (223.6–372.0 mm 3 ) suggests that most axillary nodes fall within this range, with only a few having significantly larger volumes. Although the 95% confidence interval for the quantity of axillary lymph nodes remains large (13–35), there is a relatively narrower confidence interval for the node volume, suggesting that patients with larger nodes may have fewer total nodes in the axilla. This variability may also be clinically relevant in settings where axillary lymph node size is used to indicate disease processes. Ramirez-Galvan et al. determined that the cortical thickness of lymph nodes has better diagnostic performance than lymph node apparent diffusion coefficient value when differentiating malignant axillary lymph nodes and non-malignant axillary lymph nodes in women with newly diagnosed breast cancer (29). Other studies have suggested that axillary lymph nodes > 5 mm are suspicious for malignancy and thus recommend axillary ultrasonography 30 , 31 , 32 . However, Obwegeser et al. found metastatic involvement in 9.6% of lymph nodes < 5 mm and thus rejected that recommendation. Regardless, the American College of Radiology currently recommends axillary ultrasound for patients with newly diagnosed breast cancer to assess nodal involvement, citing features such as total node size > 5 mm, critical thickness > 3 mm, and loss of fatty hilum as features indicative of metastatic involvement. Further, axillary ultrasound may be used to evaluate residual nodal disease following neoadjuvant chemotherapy 33 . Földi et al. described the size of axillary lymph nodes as ranging from pinhead size to 8 cm in length, with larger nodes generally being found in the central axillary region. The smallest nodes were found to be in the infraclavicular group. Földi also discussed that in the regions where there were fewer nodes, the nodes were generally larger in size. The largest nodes, those found to be 8cm in length, are often the result of separate members of a group fusing together 22 . Dialani et al. state that benign axillary lymph nodes typically measure less than 2 cm in length 34 . Data from this study differed from Földi, with the longest average length nodes being found in the pectoral (6.92mm) and subscapular (6.79mm) regions, while the shortest nodes, on average, were found in the central region (4.46mm). Despite the differences in average length, the median length for all regions was either 4 or 5 mm, further highlighting the outliers within the data. The absence of significant differences between the left and right sides or between sexes in lymph node quantity and volume suggests that these may not be critical factors when assessing the axillary lymph nodes in patients. The lack of statistically significant differences in lymph node distribution between male and female subjects suggests that sex and hormone cycles may have only a limited impact on lymph node presentation within the axilla. This finding could be particularly useful in avoiding unnecessary adjustments in clinical expectations based on sex alone. Ultimately, these results suggest a notable consistency in the axillary lymph node quantity and volume across sex and laterality, with the exception of the few outliers noted on volumetric analysis. These findings may help clinicians adopt a more standardized approach in evaluating axillary lymph nodes while supporting the idea that differences may not exist between sexes or laterality. Researchers in this study went through a thorough educational session to ensure all dissected lymph nodes were documented accurately to increase the accuracy and validity of the data. Though this study aimed to reduce limitations, a few limitations were documented: When researchers were excising the lymph nodes out of the body, a few were torn or cut. In addition, researchers measured all lymph nodes and excluded measuring lymph nodes damaged during excision. Those lymph nodes were, however, included in the overall count of lymph nodes. Lastly, researchers were limited to post-dissections of human cadavers. Therefore, lymph nodes were potentially removed before the researchers performed the lymph node dissections. Future studies should expand on these findings by including larger and more diverse cohorts, potentially exploring correlations with specific pathologies to refine clinical decision-making further. Conclusion The lymphatic system is crucial in draining interstitial fluid and preventing edema. However, it is often disrupted during cancer assessment and treatment, particularly for metastasis evaluation. This disruption is known to frequently be complicated by the development of lymphedema. This study evaluated and quantified the lymph nodes in the axillary region, finding smaller average ranges within specific axillary lymph node regions in the axilla. The volume of axillary lymph nodes was also evaluated, reporting a relatively narrow confidence interval and finding a potentially inverse relationship between the volume of individual axillary lymph nodes and the total number of lymph nodes. No difference was found when comparing left and right axillary lymph nodes or axillary nodes in males and females. These findings could offer valuable guidance to physicians in planning surgical approaches involving axillary lymph nodes while also enhancing prognosis and postoperative care strategies for patients. Declarations Ethics approval and consent to participate is not applicable to this paper as stated by Philadelphia College of Osteopathic Medicine’s Division of Research. The exempt statement from Philadelphia College of Osteopathic Medicine’s Division of Research will be attached as a separate file. The need for consent was also waived by Philadelphia College of Osteopathic Medicine’s Division of Research. There was no individual data in this research. The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request [Shelley DiCecco / [email protected] ]. The authors declare they have no competing interests. There was no funding granted for this research study, however we would like to thank the Philadelphia College of Osteopathic Medicine, Georgia Campus, for access to their cadaver lab and resources. Authorship: Nicholas Robinson made substantial contributions to writing the manuscript, Samuel Ighodaro made substantial contributions in the acquisition and analysis of the data, Casey Thompson made substantial contributions in the acquisitions and analysis of the data, Mierra Robinson made substantial contributions in the writing of the manuscript, and Shelley DiCecco, made significant contributions in the conceptualization, design of the work, and editing of the manuscript. All authors have approved of this final manuscript. Shelley DiCecco is the corresponding author. Author Contribution Nicholas Robinson made substantial contributions to writing the main manuscript and forming all tables. Samuel Ighodaro made substantial contributions in the acquisition and analysis of the data. Casey Thompson made substantial contributions in the acquisitions and analysis of the data and forming all figures. Mierra Robinson made substantial contributions in the writing and proofreading the manuscript. Shelley DiCecco made significant contributions in the conceptualization, design of the work, and editing of the manuscript. All authors reviewed the manuscript. Data Availability The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request [Shelley DiCecco / [ [email protected] ](/mailto: [email protected] ) ]. References Suami H. Anatomical theories of the pathophysiology of cancer-related lymphoedema. 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Epub 2020 Feb 16. PMID: 32064890. Bruneton JN, Caramella E, Hery M, et al. Axillary lymph node metastases in breast cancer: preop-erative detection with US. Radiology. 1986;158:325. Pamilo M, Soiva M, Lavast EM. Real-time ultrasound, axillary mammography and clinical examination in the detection of axillary lymph node metastases in breast cancer patients. J Ultrasound Med. 1989;8:115. Tate JJ, Lewis V, Archer T, et al. Ultrasound detection of axillary lymph node metastases in breast cancer. Eur J Surg Oncol. 1989;15:139. ; Expert Panel on Breast Imaging, Le-Petross HT, Slanetz PJ, Lewin AA et al. ACR Appropriateness Criteria® Imaging of the Axilla. J Am Coll Radiol. 2022;19(5S):S87-S113. 10.1016/j.jacr.2022.02.010 . PMID: 35550807. Dialani V, James DF, Slanetz PH. A Practical Approach to Imaging the Axilla. Insights Imaging. 2015 APR;6(2):217 – 29. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 15 Oct, 2025 Reviewers agreed at journal 12 Oct, 2025 Reviewers agreed at journal 05 Oct, 2025 Reviewers agreed at journal 25 Sep, 2025 Reviewers invited by journal 25 Sep, 2025 Editor assigned by journal 09 Sep, 2025 Editor invited by journal 02 Sep, 2025 Submission checks completed at journal 22 Aug, 2025 First submitted to journal 22 Aug, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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1","display":"","copyAsset":false,"role":"figure","size":67188,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eTotal quantity of axillary lymph nodes.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7366855/v1/8a90b474ce28aab9f57b4f8c.png"},{"id":93019094,"identity":"f72357f0-7827-48cf-8f1d-9c229888f3ce","added_by":"auto","created_at":"2025-10-08 08:30:37","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":58722,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eTotal volume of axillary lymph nodes (mm\u003c/em\u003e\u003csup\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e).\u003c/em\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7366855/v1/b538841cb99a4f8e57ce2b78.png"},{"id":93018071,"identity":"6778120e-099b-431e-ab17-008c11f3e959","added_by":"auto","created_at":"2025-10-08 08:22:37","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":47851,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eMale and female axillary lymph node quantities.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7366855/v1/4befb79494a21aa258edaa1a.png"},{"id":93019095,"identity":"bc4baa29-5461-404a-9962-37e3d3d08dea","added_by":"auto","created_at":"2025-10-08 08:30:37","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":42576,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eMale and female axillary lymph node volumes (mm\u003c/em\u003e\u003csup\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e).\u003c/em\u003e\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7366855/v1/7db5a764fc5bc14fd51eaae9.png"},{"id":93019515,"identity":"2cb8cb96-cda6-472c-88ce-34e119fb3da4","added_by":"auto","created_at":"2025-10-08 08:38:38","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":47859,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eLeft and right-sided axillary lymph node quantities\u003c/em\u003e.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7366855/v1/57f1a5291635f44d512284c2.png"},{"id":93018073,"identity":"bc537a39-34e9-4cc3-9477-912e24e80bb1","added_by":"auto","created_at":"2025-10-08 08:22:37","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":39318,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eLeft and right-sided axillary lymph node volumes (mm\u003c/em\u003e\u003csup\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e).\u003c/em\u003e\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7366855/v1/7accd6b6922da474e3386e99.png"},{"id":93020997,"identity":"cf3ee3aa-55c5-4605-a029-cd668ca0c6f2","added_by":"auto","created_at":"2025-10-08 08:46:38","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1106877,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7366855/v1/f801425d-bd72-4ad7-8427-b809e6dc53b9.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"A Quantitative Analysis of Axillary Lymph Nodes","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe lymphatic system comprises a complex network of vessels, nodes, and tissues that eliminates fluid, waste, and protein from the interstitial spaces. Additionally, it serves an immunological role, facilitating the movement of immune cells as they combat pathogens and foreign substances\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. However, lymph nodes are the most common site of solid tumor metastasis and can contribute to the spread of malignant disease\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. In treating certain malignancies such as breast cancer, physicians will stage and assess the spread of cancer via the removal and pathological analysis of lymph nodes. This is often accomplished via procedures such as an axillary lymph node dissection (ALND) or a sentinel lymph node biopsy (SLNB)\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eA lymph node dissection (lymphadenectomy) is a procedure where some or all of the lymph nodes within a region near a malignancy are removed and analyzed for the spread of cancer. An ALND for breast cancer involves an incision across the patient's axilla followed by removal of lymph nodes located lateral to the pectoralis minor muscle (level I) and lymph nodes located directly under the pectoralis minor (level II)\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. As with other surgical procedures, common complications include pain, surgical site swelling, and infection. Lymphedema is another, often more distressing, complication associated with ALND\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. Lymphedema is an insufficiency of lymphatic system drainage, which can create issues in fluid and tissue homeostasis\u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. It classically presents as swelling of the affected area, often an extremity, because the fluid and debris in the interstitium cannot fully drain back into the lymphatic system. This fluid accumulation in the tissue may cause additional symptoms, including pain or discomfort, extremity heaviness or fullness, numbness or tingling, fatigue or strength deficits, and reduced motion. If the lymphatic system is insufficient, the buildup of lymphatic fluid causes a chronic inflammatory process, leading to fibrosis, adipose tissue deposition, and thickening of tissues, including surrounding skin\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eHistorically, many women diagnosed with breast cancer underwent ALND unnecessarily because many or all of their nodes were negative for metastases. Removing many lymph nodes within a region dramatically increases the incidence of complications, especially lymphedema\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. Performing an SLNB before lymphadenectomy has reduced the incidence of these complications by removing fewer lymph nodes in patients with limited nodal involvement\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. To perform an SLNB, the sentinel node is identified via tracer dye injected into the primary malignancy. A surgeon will then follow which node(s) take up the dye and remove that node(s). The sample(s) is then sent to a pathologist to analyze for the presence of cancer, and if present, the surgeon will remove more lymph nodes. A negative biopsy result suggests that the cancer has not spread to other organs or the lymphatic system. However, a positive result suggests the malignancy has spread to the sentinel node and possibly to regional nodes or other nearby organs\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. Sometimes, a patient may still need an ALND\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. According to the American Society of Breast Surgeons, indications to still perform an ALND if the patient has early-stage breast cancer (T1/T2) include having 3 or more positive lymph nodes on SLNB, palpable biopsy-confirmed axillary lymph node involvement in patients not receiving neoadjuvant chemotherapy, or with persistently palpable axillary lymph nodes after receiving neoadjuvant chemotherapy. Other indications include large or locally advanced breast cancer (T3/T4) or inflammatory breast cancer\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eThe American College of Surgeons Oncology Group (ACOSOG) Z0011 trial found that patients with T1/T2 tumors who lacked palpable axillary lymphadenopathy could avoid ALND as part of the breast-conserving surgery (BCS) even if sentinel node testing was positive for metastasis. When comparing those who underwent an SLNB to those who had both SLNB and ALND, there was no statistically significant difference regarding local or regional malignancy recurrence rates or the 5-year overall survival rate, further supporting the use of SLNB\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e. Further, there is evidence that there is no difference in survival rate in early-stage breast cancer patients post an SLNB compared to ALND\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eLymphedema occurs as a secondary complication in up to 15% of cancer treatments, making cancer treatment the most common cause of lymphedema in developed countries\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. A previous review found that ALNDs resulted in a 4 times greater incidence of arm lymphedema than an SLNB alone\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e. Yen et al. demonstrated that the removal of 15 nodes compared to the removal of 5 nodes in a lymphadenectomy performed for breast cancer treatment resulted in a tenfold increase in the incidence of lymphedema\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. McLaughlin et al. found the incidence of patients developing upper extremity lymphedema was 3% (18 out of 600) for those with only a sentinel node biopsy and 27% (91 out of 336) in the patients who underwent sentinel node biopsy and axillary node lymphadenectomy\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e. This data supports that SLNB alone results in fewer patients developing lymphedema than the combination of SLNB and ALND or ALND alone. Unfortunately, since lymph node status is the primary prognostic factor for breast cancer, the ALND has remained a significant determinant for the use of adjuvant therapy despite the high morbidity risk\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eIt is, therefore, beneficial to more precisely determine the minimal number of lymph nodes a physician could remove during an ALND to optimize metastasis diagnosis while minimizing the risk of lymphedema. For example, Peyre et al. found that removing a minimum of 23 regional lymph nodes was required for the maximal survival rate in esophageal cancer patients\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. Koppie et al. stated that there is no minimum number of lymph nodes a surgeon should remove to maximize survival rates in patients with transitional cell carcinoma, suggesting that the more lymph nodes removed, the higher the survival rate\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e. Currently, ranges for regional and total lymph nodes in the body vary significantly within the axilla, thus making it difficult to recommend an appropriate number of lymph nodes to be removed for any singular patient\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e. Current data suggests an average of 20 to 30 axillary lymph nodes, although there is significant variation at the individual level\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. Many previous studies also do not differentiate node size, which can vary greatly, on average between 0.2 and 3.0 mm. The cause of this is still highly disputed. However, some theories include changes due to menstrual cycle patterns or failure of the nodes to divide in utero, leading to larger but fewer lymph nodes in a given region\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eFor those reasons, more accurate data regarding lymph node ranges and averages in the axilla will help healthcare providers decide the risks and benefits of removing additional lymph nodes in the management of metastatic breast malignancies. This data will also allow healthcare providers to more accurately discuss prognosis and risks with their patients before undergoing lymphadenectomies and to set realistic expectations. This study aims to identify more precise axilla lymph node ranges and averages.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eEmbalming and dissection of cadavers\u003c/h2\u003e\u003cp\u003eThe cadavers utilized for this study were donated to the Georgia Campus of the Philadelphia College of Osteopathic Medicine (PCOM). Dissections were carried out by students from the Doctor of Osteopathic Medicine (DO), Physician Assistant (PA), and Physical Therapy (PT) programs over several academic terms between 2019 and 2023. Prior to the dissections, all students received instruction on the lymphatic system, lymph nodes, and the study's procedures from Dr. Shelley DiCecco, a faculty member in the Physical Therapy Department and the lead investigator. The cadavers were embalmed onsite at PCOM using standardized techniques.\u003c/p\u003e\u003cp\u003eThe cadavers were initially treated with a solution known as the Maryland State Blend (MSB), produced by Hydrol Chemical Company in Pennsylvania. This solution was specifically tailored to suit Georgia\u0026rsquo;s environmental conditions. Before injection, the MSB was diluted by adding one gallon of water for every ten ounces of the solution. An initial injection of 4 to 5 gallons was administered over a 2\u0026ndash;3 day period for most cadavers. An additional 3 to 4 gallons were then injected until the vascular system reached optimal saturation, as determined by PCOM\u0026rsquo;s Director of Anatomical Donor Services. For final preparation, the embalmed cadavers were wrapped in cotton soaked in a diluted MSB solution, encased in plastic, and stored in a zipper pouch. They were then placed in a refrigeration unit for approximately 4 to 8 months before being used for dissection.\u003c/p\u003e\u003cp\u003eThe research team comprised the lead investigator, 12 DO students, and 5 biomedical sciences students. PCOM students typically performed dissections in the afternoons, 4\u0026ndash;5 days per week. The lead researchers would follow up on these dissections in the mornings, examining the bodies for lymph nodes in the targeted regions. When a lymph node was identified, it was tagged using a tag gun, and its location and surface area were recorded. The lymph nodes were left intact until the students completed the academic quarter. Researchers regularly revisited the areas to document any newly discovered nodes. At the end of the quarter, the researchers removed all organs, tissues, and nodes to ensure any remaining lymph nodes were identified. The surface area of each node was measured in millimeters using a standard ruler. The size and location of the nodes were documented on a grid during dissections and later transferred to a data spreadsheet for analysis.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eCadavers\u003c/h3\u003e\n\u003cp\u003eThe demographics of the 72 cadavers were 41 female and 31 male, ages 39 to 103 (mean age 73.2 +/- 11.2), with 62 Caucasian, 6 African American, 3 Asian, and 1 of Hispanic ethnicity. The cause of death for each cadaver was unknown during the experiment to prevent bias. The 72 cadavers were examined for paired regions of right and left central, humeral, infraclavicular, parasternal, pectoral, and subscapular lymph nodes. Anatomical landmarks were used to identify each region of nodes.\u003c/p\u003e\n\u003ch3\u003eAnatomical landmarks for identifying lymph nodes per region\u003c/h3\u003e\n\u003cp\u003eStandard anatomical landmarks were used to identify and distinguish the different lymph node regions. The landmarks used were based on anatomical descriptions from multiple references\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e. PCOM students conducting the dissections were given a lecture about the research being conducted and the location of the nodes using illustrations of anatomical landmarks. The following are the descriptions given to students, as well as the anatomical landmarks that were used to define the axillary lymph node groups in this study:\u003c/p\u003e\n\u003ch3\u003eCentral Nodes\u003c/h3\u003e\n\u003cp\u003eThe central nodes are embedded in fatty tissue at the base of the axilla. They are adjacent to the intercostobrachial nerves, close to the 2nd segment of the axillary artery. Typically, the central nodes are under the fascia and deep to the pec minor.\u003c/p\u003e\n\u003ch3\u003eHumeral Nodes\u003c/h3\u003e\n\u003cp\u003eHumeral nodes, or lateral nodes, are located along the latissimus dorsi tendon, where it joins the axillary and subscapular veins. These nodes are posterior and medial to the axillary vein on the lateral wall by the medial cutaneous brachial nerve.\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eInfraclavicular Nodes\u003c/h2\u003e\u003cp\u003eThe infraclavicular, or apical, nodes are embedded in the fatty tissue of the clavipectoral triangle, located superior to the 1st intercostal space, at the origin of the serratus anterior muscle. The nodes are located medially to the end segment of the axillary vein and the first segment of the axillary artery. The pectoral major and minor muscles and the associated fascia protect these nodes. A subset of this group, the deltopectoral, consists of 1\u0026ndash;2 nodes that can be found below the clavicle between the pec major and deltoid, along the cephalic vein.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eParasternal Nodes\u003c/h3\u003e\n\u003cp\u003eParasternal, or internal mammary, nodes are located in the intercostal spaces 1\u0026ndash;6, approximately 3 cm from the sternum, near the internal thoracic artery and vein. The transverse thoracic muscle and endothoracic fascia protect these nodes.\u003c/p\u003e\n\u003ch3\u003ePectoral Nodes\u003c/h3\u003e\n\u003cp\u003eThe pectoral nodes are found on the medial wall of the axilla on top of the muscle belly of the serratus anterior, typically under a thin layer of adipose tissue. The nodes are found between the 2nd, 3rd, 6th, or 7th ribs with the lateral thoracic artery and vein. Frequently, these nodes are found either behind or at the inferior border of the pectoralis minor muscle. A subset, the interpectoral nodes, present 50% of the time, are located at the bifurcation of the thoracoacromial artery between the pectoralis muscles.\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eSubscapular Nodes\u003c/h2\u003e\u003cp\u003eSubscapular nodes are against the posterior wall of the axilla around the thoracodorsal and subcapular veins. The nodes are divided into 2 groups, with the upper nodes on the inferior portion of the subscapularis muscle and the lower group between the teres minor and latissimus dorsi muscle bellies. There is minimal adipose coverage for the protection of these nodes. Three nerves are also found near the nodes: the thoracodorsal, intercostobrachial, and subscapular.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eStatistical Analysis\u003c/h2\u003e\u003cp\u003eStatistical analysis of the recorded data was performed using Excel spreadsheets and SPS Analytics. Cadavers were excluded from analysis if they failed to meet the predetermined lower boundary of one per region. Lower-end ranges from various sources were initially set, yet the study went with \u0026ldquo;1\u0026rdquo; to see if these previous studies were accurate in minimal numbers per region\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e. A univariate analysis was performed with data for regions being non-normal. Data analysis indicates non-normal distribution, and each section was confirmed using Q-Q plots. A Wilcoxon Two-Sample non-parametric test was used for comparison with an alpha value of 0.05.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003e\u003cem\u003eQuantity of axillary lymph nodes broken down by region.\u003c/em\u003e\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003emean\u0026thinsp;\u0026plusmn;\u0026thinsp;STD Dev\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMin-Max\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e95% CI\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eParasternal\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4.36\u0026thinsp;\u0026plusmn;\u0026thinsp;2.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u0026ndash;10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.90\u0026ndash;4.82\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eInfraclavicular\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.74\u0026thinsp;\u0026plusmn;\u0026thinsp;1.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u0026ndash;9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.35\u0026ndash;3.12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eCentral\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.32\u0026thinsp;\u0026plusmn;\u0026thinsp;2.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u0026ndash;10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.90\u0026ndash;3.75\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003ePectoral\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.98\u0026thinsp;\u0026plusmn;\u0026thinsp;4.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u0026ndash;19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e5.46\u0026ndash;6.49\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eSubscapular\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.76\u0026thinsp;\u0026plusmn;\u0026thinsp;2.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u0026ndash;11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.27\u0026ndash;4.25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eHumeral\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.30\u0026thinsp;\u0026plusmn;\u0026thinsp;1.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u0026ndash;6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.95\u0026ndash;2.66\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eAll quantitative analyses were performed using JMP15 and Excel spreadsheets. Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e shows the distribution analysis for each lymph node region within the axilla. Figure \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e is a graphic representation of the quantity of all axillary nodes. A univariate analysis was performed. Analysis of that data was non-normal and confirmed with Q-Q plots. The pectoral region had the greatest range of lymph nodes, with one subject having 19 pectoral lymph nodes. However, the confidence interval for that group remained relatively narrow, from 5.46\u0026ndash;6.49. The Humeral region had the smallest range from 0\u0026ndash;6 and a narrow confidence interval.\u003c/p\u003e\n\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e is a graphic representation of the total volume of axillary lymph nodes. The overall range was wide from 21.1 to 3770.3 mm\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. However, a relatively narrow confidence interval (223.6\u0026ndash;372.0 mm\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e) suggests the presence of several outliers with significantly larger volumes. Despite this range, the second largest volume in our data was 1115.8 mm\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eA Wilcoxon Two-same non-parametric test was used to determine differences in laterality and to compare male and female subjects. Figure \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e is a graphical representation of male vs female axillary lymph node quantities. For this study, the null hypothesis may be rejected if the p-value\u0026thinsp;\u0026le;\u0026thinsp;0.05. There was no statistically significant difference (p\u0026thinsp;=\u0026thinsp;0.13) between the quantity of axillary lymph nodes in males and females. There is also no statistically significant difference (p\u0026thinsp;=\u0026thinsp;0.27) between axillary lymph node volumes in males and females, as represented by Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e\n\u003cp\u003eFigures \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e and \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e are graphical representations comparing the quantity and volume, respectively, of axillary lymph nodes on the right and left sides. Again, there was no statistically significant difference in quantity (p\u0026thinsp;=\u0026thinsp;0.58) or volume (p\u0026thinsp;=\u0026thinsp;0.64) between sides.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2\u003c/strong\u003e shows the quantity and volume of the total axillary lymph nodes. The 95% confidence interval, total range, average range, and the mean with standard deviation are also reported within this table. \u003cstrong\u003eTable 3\u003c/strong\u003e compares the average ranges of lymph nodes in each anatomical grouping from this study with three previously published sources. \u003cstrong\u003eTable 4\u003c/strong\u003e depicts the average and median lengths for all axillary lymph nodes within each region.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2:\u0026nbsp;\u003c/strong\u003e\u003cem\u003eTotal quantity and volume of axillary lymph nodes.\u003c/em\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"624\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e\u003cstrong\u003emean\u0026plusmn;STD Dev\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAvg Range\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMin-Max\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e95% CI\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAxilla Node Quantity\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e13.69\u0026plusmn;10.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e12-14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e1-50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e13-35\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAxilla Node Volume (mm\u003csup\u003e3\u003c/sup\u003e)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e297.8\u0026plusmn;37.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e15780-15786\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e21.1-3770.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e223.6-372.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3:\u003c/strong\u003e \u003cem\u003eAverage ranges for each anatomical grouping in this study compared to previous data.\u003c/em\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"624\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLymph Node Anatomical Grouping\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAverage Range from Current Study\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAverage and Median Range from F\u0026ouml;ldi et al.\u003csup\u003e22\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eStandring\u003csup\u003e23\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eZuther\u003csup\u003e28\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMoore\u003csup\u003e25\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCentral\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e2-5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e3-6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e3-4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHumeral\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e1-3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e4-6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eInfraclavicular\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e2-4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e1-6 or 7-12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eParasternal\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e4-7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e4-6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePectoral\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e4-7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e2-6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e3-5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSubscapular\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e2-5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e1-8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e6-7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOverall Lymph Node Range for Axilla\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e15-31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e10-34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e20-30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e10-24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e4-7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4:\u0026nbsp;\u003c/strong\u003e\u003cem\u003eAverage and median lengths for each axillary lymph node group\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"624\" class=\"fr-table-selection-hover\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLymph Node Anatomical Grouping\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAverage Length (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMedian Length (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCentral\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e4.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHumeral\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e4.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eInfraclavicular\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e5.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eParasternal\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e7.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePectoral\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e6.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSubscapular\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e6.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTotal Axillary Lymph Nodes\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e6.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe study addresses the challenge of balancing accurate cancer staging with minimizing the risk of complications such as lymphedema, a common consequence of lymphadenectomy procedures like axillary lymph node dissection (ALND). The benefits of identifying more precise lymph node ranges in the axilla are clear, as doing so will help guide surgical decision-making in a way that both improves patient outcomes and reduces the morbidity associated with cancer treatment\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. Further, knowing more precise lymph node ranges may also assist in establishing a prognosis of developing lymphedema for patients who have already undergone SLNB or ALND. For example, one study found that patients undergoing excision of more than 5 lymph nodes are at a significantly increased risk of developing lymphedema\u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e. However, if clinicians have a better understanding of differences across patient populations, they may be able to provide a more specific prognosis to their patients. With more precise ranges, clinicians may also be able to provide more informed expectations of improvement with treatment for those already diagnosed with lymphedema.\u003c/p\u003e\u003cp\u003eThe quantitative analysis of axillary lymph nodes presented in this study provides new insights into axillary lymph nodes' distribution and volumetric variability, which may have implications for clinical decision-making, particularly in surgical planning and oncologic evaluation. Further, this study included a larger sample size with more variety in races and sexes of the subjects compared to previously published data. One of the primary findings is the marked variability in the number of lymph nodes within the pectoral region. Despite one subject having 19 nodes on dissection, the relatively narrow confidence interval (5.46\u0026ndash;6.49) suggests that although there is a relatively consistent number of nodes within this region, significant outliers exist, highlighting the need for clinicians to consider potential anatomic outliers. By contrast, the humeral region displayed a smaller range of lymph nodes (0\u0026ndash;6) with a similarly narrow confidence interval (1.95\u0026ndash;2.66), suggesting less anatomical variability within this region. This distinction may be valuable for guiding clinicians on where to anticipate more significant variability in lymph node distribution within the axilla. However, more studies should be conducted to determine the cause or significance of any variability difference within the regions.\u003c/p\u003e\u003cp\u003eWhen evaluating lymph node volume, these findings indicated a wide range (21.1-3770.3 mm\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e) with an outlier significantly skewing the upper limit. The narrow confidence interval (223.6\u0026ndash;372.0 mm\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e) suggests that most axillary nodes fall within this range, with only a few having significantly larger volumes. Although the 95% confidence interval for the quantity of axillary lymph nodes remains large (13\u0026ndash;35), there is a relatively narrower confidence interval for the node volume, suggesting that patients with larger nodes may have fewer total nodes in the axilla. This variability may also be clinically relevant in settings where axillary lymph node size is used to indicate disease processes.\u003c/p\u003e\u003cp\u003eRamirez-Galvan et al. determined that the cortical thickness of lymph nodes has better diagnostic performance than lymph node apparent diffusion coefficient value when differentiating malignant axillary lymph nodes and non-malignant axillary lymph nodes in women with newly diagnosed breast cancer (29). Other studies have suggested that axillary lymph nodes\u0026thinsp;\u0026gt;\u0026thinsp;5 mm are suspicious for malignancy and thus recommend axillary ultrasonography\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e. However, Obwegeser et al. found metastatic involvement in 9.6% of lymph nodes\u0026thinsp;\u0026lt;\u0026thinsp;5 mm and thus rejected that recommendation. Regardless, the American College of Radiology currently recommends axillary ultrasound for patients with newly diagnosed breast cancer to assess nodal involvement, citing features such as total node size\u0026thinsp;\u0026gt;\u0026thinsp;5 mm, critical thickness\u0026thinsp;\u0026gt;\u0026thinsp;3 mm, and loss of fatty hilum as features indicative of metastatic involvement. Further, axillary ultrasound may be used to evaluate residual nodal disease following neoadjuvant chemotherapy\u003csup\u003e\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eF\u0026ouml;ldi et al. described the size of axillary lymph nodes as ranging from pinhead size to 8 cm in length, with larger nodes generally being found in the central axillary region. The smallest nodes were found to be in the infraclavicular group. F\u0026ouml;ldi also discussed that in the regions where there were fewer nodes, the nodes were generally larger in size. The largest nodes, those found to be 8cm in length, are often the result of separate members of a group fusing together\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. Dialani et al. state that benign axillary lymph nodes typically measure less than 2 cm in length\u003csup\u003e\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eData from this study differed from F\u0026ouml;ldi, with the longest average length nodes being found in the pectoral (6.92mm) and subscapular (6.79mm) regions, while the shortest nodes, on average, were found in the central region (4.46mm). Despite the differences in average length, the median length for all regions was either 4 or 5 mm, further highlighting the outliers within the data.\u003c/p\u003e\u003cp\u003eThe absence of significant differences between the left and right sides or between sexes in lymph node quantity and volume suggests that these may not be critical factors when assessing the axillary lymph nodes in patients. The lack of statistically significant differences in lymph node distribution between male and female subjects suggests that sex and hormone cycles may have only a limited impact on lymph node presentation within the axilla. This finding could be particularly useful in avoiding unnecessary adjustments in clinical expectations based on sex alone.\u003c/p\u003e\u003cp\u003eUltimately, these results suggest a notable consistency in the axillary lymph node quantity and volume across sex and laterality, with the exception of the few outliers noted on volumetric analysis. These findings may help clinicians adopt a more standardized approach in evaluating axillary lymph nodes while supporting the idea that differences may not exist between sexes or laterality.\u003c/p\u003e\u003cp\u003eResearchers in this study went through a thorough educational session to ensure all dissected lymph nodes were documented accurately to increase the accuracy and validity of the data. Though this study aimed to reduce limitations, a few limitations were documented: When researchers were excising the lymph nodes out of the body, a few were torn or cut. In addition, researchers measured all lymph nodes and excluded measuring lymph nodes damaged during excision. Those lymph nodes were, however, included in the overall count of lymph nodes. Lastly, researchers were limited to post-dissections of human cadavers. Therefore, lymph nodes were potentially removed before the researchers performed the lymph node dissections.\u003c/p\u003e\u003cp\u003eFuture studies should expand on these findings by including larger and more diverse cohorts, potentially exploring correlations with specific pathologies to refine clinical decision-making further.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe lymphatic system is crucial in draining interstitial fluid and preventing edema. However, it is often disrupted during cancer assessment and treatment, particularly for metastasis evaluation. This disruption is known to frequently be complicated by the development of lymphedema. This study evaluated and quantified the lymph nodes in the axillary region, finding smaller average ranges within specific axillary lymph node regions in the axilla. The volume of axillary lymph nodes was also evaluated, reporting a relatively narrow confidence interval and finding a potentially inverse relationship between the volume of individual axillary lymph nodes and the total number of lymph nodes. No difference was found when comparing left and right axillary lymph nodes or axillary nodes in males and females. These findings could offer valuable guidance to physicians in planning surgical approaches involving axillary lymph nodes while also enhancing prognosis and postoperative care strategies for patients.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003cp\u003eis not applicable to this paper as stated by Philadelphia College of Osteopathic Medicine\u0026rsquo;s Division of Research. The exempt statement from Philadelphia College of Osteopathic Medicine\u0026rsquo;s Division of Research will be attached as a separate file. The need for consent was also waived by Philadelphia College of Osteopathic Medicine\u0026rsquo;s Division of Research. There was no individual data in this research. The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request [Shelley DiCecco / \u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\[email protected]\u003c/span\u003e]. The authors declare they have no competing interests. There was no funding granted for this research study, however we would like to thank the Philadelphia College of Osteopathic Medicine, Georgia Campus, for access to their cadaver lab and resources. Authorship: Nicholas Robinson made substantial contributions to writing the manuscript, Samuel Ighodaro made substantial contributions in the acquisition and analysis of the data, Casey Thompson made substantial contributions in the acquisitions and analysis of the data, Mierra Robinson made substantial contributions in the writing of the manuscript, and Shelley DiCecco, made significant contributions in the conceptualization, design of the work, and editing of the manuscript. All authors have approved of this final manuscript. Shelley DiCecco is the corresponding author.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eNicholas Robinson made substantial contributions to writing the main manuscript and forming all tables. Samuel Ighodaro made substantial contributions in the acquisition and analysis of the data. Casey Thompson made substantial contributions in the acquisitions and analysis of the data and forming all figures. Mierra Robinson made substantial contributions in the writing and proofreading the manuscript. Shelley DiCecco made significant contributions in the conceptualization, design of the work, and editing of the manuscript. All authors reviewed the manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request [Shelley DiCecco / [[email protected]](/mailto:[email protected]) ].\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSuami H. Anatomical theories of the pathophysiology of cancer-related lymphoedema. 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A Practical Approach to Imaging the Axilla. \u003cem\u003eInsights Imaging.\u003c/em\u003e 2015 APR;6(2):217\u0026thinsp;\u0026ndash;\u0026thinsp;29.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-cancer","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bcan","sideBox":"Learn more about [BMC Cancer](http://bmccancer.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bcan/default.aspx","title":"BMC Cancer","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Axilla, Lymph Nodes, Lymphedema, Axillary Lymph Node Biopsy, Breast Cancer","lastPublishedDoi":"10.21203/rs.3.rs-7366855/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7366855/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eAxillary lymph node dissection (ALND) is common in breast cancer treatment but carries risks like lymphedema. While sentinel lymph node biopsy (SLNB) often reduces the need for ALND, variability in lymph node number and size complicates surgical planning. This study aims to provide more precise data on axillary lymph node quantity and volume to guide surgical decisions and reduce morbidity.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eSeventy-two embalmed cadavers donated to PCOM Georgia (2019\u0026ndash;2023) were dissected to identify axillary lymph nodes using standardized anatomical landmarks. Nodes were tagged, measured, and recorded, with statistical analysis evaluating distribution by region.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eNode counts varied by region, with the pectoral region averaging 5.98 nodes and the humeral region 2.30. Total node volume ranged from 21.1\u0026ndash;3770.3 mm\u0026sup3;, though most fell within a narrower confidence interval (223.6\u0026ndash;372.0 mm\u0026sup3;). No significant differences were found by sex or side.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eThese findings reveal consistent lymph node counts across sex and laterality but notable regional variability. Narrow volume ranges support more standardized expectations in surgical planning and may improve staging accuracy and lymphedema prognosis.\u003c/p\u003e","manuscriptTitle":"A Quantitative Analysis of Axillary Lymph Nodes","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-08 08:22:33","doi":"10.21203/rs.3.rs-7366855/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2025-10-15T18:44:07+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"307838075398192487961273660574823803193","date":"2025-10-13T02:06:53+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"218707199256633926567812717155705818125","date":"2025-10-05T18:45:35+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"228212224633408852802136883516898519831","date":"2025-09-25T13:30:38+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-25T07:44:29+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-09T06:57:37+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-09-02T10:22:33+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-22T21:53:12+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Cancer","date":"2025-08-22T21:50:08+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-cancer","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bcan","sideBox":"Learn more about [BMC Cancer](http://bmccancer.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bcan/default.aspx","title":"BMC Cancer","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5c196057-592b-42c0-9daf-05d5143e86e4","owner":[],"postedDate":"October 8th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-10-08T08:22:33+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-08 08:22:33","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7366855","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7366855","identity":"rs-7366855","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}