{"paper_id":"0e1d3de9-9b94-409b-88c5-38e9458d61dc","body_text":"Male Accessory Breast Mucinous Carcinoma: A Case Report and Literature Review | 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 Case Report Male Accessory Breast Mucinous Carcinoma: A Case Report and Literature Review Junying Huang, Xi Zhou, Xingtong Zhou This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8297190/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 11 You are reading this latest preprint version Abstract Accessory breast cancer is a special type of breast cancer, accounting for approximately 0.3–0.6% of all breast cancers, of which male accessory breast cancer is even rarer. This condition typically manifests as a progressively enlarging mass, most frequently located in the axillary or inguinal regions, and may present with early lymph node metastasis. Pathological examination serves as the definitive diagnostic standard, while ultrasound, mammography and MRI are valuable ancillary diagnostic tools. Currently, the treatment for accessory breast cancer primarily references the treatment of breast cancer, employing surgical resection as the cornerstone of treatment, supplemented by endocrine therapy, chemotherapy, and radiotherapy. Here, we report a case of a 72-year-old male with accessory breast cancer. The patient was diagnosed with right axillary accessory breast cancer with right axillary lymph node metastatic cancer in 2021 and underwent right accessory mastectomy plus right axillary lymph node dissection at our hospital. Postoperatively, he has been supplemented with chemotherapy and endocrine therapy to this day. In 2025, a follow-up examination revealed a new mass in the medial aspect of the right upper arm near the axilla, and post-excisional pathology suggested it to be mucinous breast cancer. We aim to increase clinical awareness and understanding of male accessory breast cancer by detailing the discovery, clinical course, and management of this exceptionally rare case. Accessory breast cancer Male breast cancer Case report Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Accessory breast, also referred to as ectopic breast, constitutes residual breast tissue resulting from incomplete regression along the embryonic milk line. It has an estimated incidence of 2–6% and affects males and females at a ratio of 1:5, with a hereditary predisposition noted in some cases[ 1 – 3 ]. At the 6th week of embryonic development, a milk line extending from the axilla to the groin appears. Except for the chest area, the milk line at other sites gradually disappears and the undissolved part is called accessory breast[ 4 ]. Approximately 90% of accessory breasts are located along this milk line, with the remaining 10% found in extramammary locations such as the back, limbs, face, and neck[ 3 , 5 , 6 ]. Like normal breast tissue, accessory breast can be affected by hormones to produce corresponding physiological changes and common primary breast tumors, such as fibroadenoma, breast cancer, and phyllodes tumors[ 3 , 7 ]. The first documented case of accessory breast carcinoma was reported in 1861, followed by the first reported case in a male patient in 1957[ 1 , 8 , 9 ]. Accessory breast cancer is a primary malignant tumor originating from the epithelial tissue of the accessory breast, accounting for about 0.3–0.6% of all breast cancers, with a male to female ratio of 1:12.4[ 5 , 10 ]. Accessory breast cancer can occur at any position along the milk line, but it is more common in the axilla and groin; This predilection may be attributed to the rich vascular and lymphatic networks in these regions, which may also contribute to the typically aggressive clinical course, including a propensity for early metastasis[ 11 , 12 ]. This case report details a 72-year-old male patient with axillary accessory breast cancer initially diagnosed four years prior, who presented with a local recurrence in 2025. Both the initial diagnosis and subsequent management were performed at our institution. We present this rare case to summarize the clinical characteristics, diagnostic approach, therapeutic management, and prognostic considerations associated with accessory breast carcinoma, supplemented by a review of the relevant literature. Case Presentation The patient was a 72-year-old male who presented to our hospital in December 2021 with a right axillary mass that had been present for two years. Physical examination revealed a prominent right axillary mass on the body surface, with a size of approximately 3.0x4.0 cm. The skin over the mass showed no abnormalities, and no significant abnormalities were observed in both breasts. Auxiliary examinations: ultrasound indicated a hypoechoic lesion measuring 4.9x3.3x3.6 cm with a slightly irregular shape, relatively clear borders, heterogeneous internal echoes containing anechoic areas, and visible linear blood flow (Figures 1-2); mammography showed no significant abnormalities. To confirm the pathology, the patient underwent a \"right axillary mass excisional biopsy\" at our hospital. The postoperative pathology report stated: (right axillary lymph node) a cancer nodule was seen, consistent with breast mucinous carcinoma, not excluding an accessory breast origin, ER (strong positive, 85%), PR (moderate to strong positive, 50%), Her-2 (2+), Ki-67 (10%). Postoperatively, the patient underwent further PET/CT: multiple lymph nodes with increased radiotracer uptake were seen in the right axilla, the largest measuring approximately 3.0x4.0 cm, SUVmax 7.3, suggestive of a malignant lesion; no abnormal metabolic foci were seen in both breasts. Our hospital performed a \"right accessory breast resection + right axillary lymph node dissection\" on the patient. The postoperative paraffin pathology report stated: (right accessory breast and axillary lympho-fatty tissue) invasive breast carcinoma (no special type, partially mucinous carcinoma, moderately differentiated, size 4x3.5x2.5 cm), lymph nodes showed chronic inflammation (0/25); ER (strong positive, 95%), PR (moderate positive, 80%), Her-2 (1+), Ki-67 (40%). Postoperatively, the patient received six cycles of adjuvant capecitabine chemotherapy, followed by maintenance anastrozole endocrine therapy. Regular follow-ups during this period showed no recurrence or metastasis (the last follow-up breast and axillary ultrasound was in April 2025, which was unremarkable at that time). In June 2025, the patient palpated a mass of about 4 cm near the right axillary incision, close to the medial side of the upper arm, which was hard, relatively fixed, without significant tenderness and accompanied by mild edema of the right upper limb. An ultrasound (2025-7-17) revealed a hypoechoic lesion in the right axilla, approximately 4.9x3.3x2.5 cm in size, with an irregular shape, relatively clear borders, and visible blood flow within (Figure 3); MRI: a mass-like high-signal intensity was seen in the right axilla, measuring approximately 49x36 mm (Figure 4). A PET/CT was completed: a slightly low-density lesion with slightly increased radiotracer uptake was seen in the right shoulder muscle, measuring 2.9x2.5 cm, SUVmax 2.8, which needed to exclude the possibility of malignancy, with no distant metastasis seen (Figure 5). The patient subsequently underwent a “right axillary mass needle biopsy” and the biopsy pathology was metastatic breast mucinous carcinoma. In September 2025, the patient underwent a “wide excision of the right axillary tumor” at our hospital again. Intraoperatively, a red-white tumor was found within the coracobrachialis muscle under the right axillary scar, which was hard, approximately 5x4x3 cm in size, lobulated, with relatively clear borders, and the tumor was close to the main axillary artery and vein (Figures 6-8). During the operation, the wound was soaked with 50 mg cisplatin + 300 ml of hot distilled water for 10 minutes. Postoperative pathology indicated (right axillary tumor) metastatic breast mucinous carcinoma, ER (strong positive, 90%), PR (strong positive, 90%), Her-2 (2+), Ki-67 50%. Combined with the patient's previous medical history, it is now considered that the patient has local recurrence of accessory breast carcinoma. Postoperatively, based on the pathology, the endocrine therapy regimen was changed to a CDK4/6 inhibitor + anastrozole. Discussion Breast cancer is one of the most common malignant tumors among women worldwide, with male breast cancer accounting for less than 1% and accessory breast cancer accounting for 0.3-0.6%, while only 0.2-1.2% of men have accessory breasts[13, 14]. Consequently, male accessory breast cancer is exceptionally uncommon, and current literature is limited to sporadic case reports and small retrospective studies due to insufficient large-scale statistical data. The etiology of accessory breast cancer is unclear, and some studies suggest that risk factors closely related to breast cancer may also induce supernumerary breast cancer, such as genetic factors, enhanced estrogen or estrogen-androgen imbalance, and environmental influences (electromagnetic fields, high temperature, formaldehyde, etc.)[15]. Epidemiology and Clinical Presentation The age at diagnosis for accessory breast cancer ranges from 28 to 90 years, with a peak incidence between 40 and 45 years, accounting for about 50% of all cases[6]. Pang et al. analyzed 16 cases of male accessory breast cancer patients, finding that most were Asian, with ages ranging from 51 to 87 years and an average age of 67.1 years[1]. Early-stage accessory breast cancer is typically asymptomatic. As the tumor progresses, it typically presents as a firm, poorly defined and irregularly shaped mass within the accessory breast tissue with an average diameter of 2.8 cm; Some patients may experience accompanying pain and swelling, when the surface of the mass is involved, it can appear light red, purplish-red, or exhibit an orange peel appearance, ulcers or purulent discharge may occur in severe cases. Most patients seek medical attention only when clear symptoms are present, which typically occurs long after the disease has onset, leading to delays in treatment[1, 6, 16-19]. Furthermore, the clinical presentation of accessory breast cancer is not specific and is difficult to distinguish from benign axillary masses (such as lipomas, tuberculous lymphadenitis, reactive lymphadenopathy) or malignant masses (such as lymph node metastatic carcinoma, appendageal tumors). Studies have found that 58% of accessory breast cancers occur in the axilla, 18.5% in the parasternal region, 6.8% in the subclavian area, 8.6% in the sub mammary region, and 4% in the vulva[8]. Accessory breast cancer in the axilla is often accompanied by enlarged and fused ipsilateral axillary or supraclavicular lymph nodes. Accessory breast cancer in the groin region can also involve enlarged and fused ipsilateral inguinal lymph nodes. Regarding metastasis, 50% of patients with accessory breast cancer already exhibit axillary lymph node metastasis at the time of initial diagnosis[12, 18]. Accessory breast cancer can also lead to invasion and metastasis to adjacent organs, such as thoracic, cerebellar, and bone metastases, but these typically occur in the later stages of the disease[1]. In summary, accessory breast cancer most commonly metastasizes to the ipsilateral axillary lymph nodes, followed by metastasis to the supraclavicular lymph nodes. Therefore, some studies suggest that when internal mammary lymph node metastasis is present, it should be considered as M1 (distant metastasis) rather than N1-2 (regional lymph node metastasis)[6, 20]. In the case of this patient, the 72-year-old elderly male presented with a firm, approximately 4 cm mass in the right axilla during both visits. The overlying skin showed no obvious involvement, and the patient had no significant accompanying symptoms, which is consistent with the clinical presentation of accessory breast cancer. The presence of metastatic cancer nodules in the right axillary lymph nodes at the time of the first visit confirms the tendency for axillary accessory breast cancer to develop lymph node metastases early in the disease course. The right upper limb edema observed during the second recurrence was likely a result of impaired lymphatic drainage caused by the combination of a previous axillary lymph node dissection and the current axillary tumor burden. Diagnosis Due to its rarity, the diagnosis of male accessory breast cancer is extremely difficult. The diagnosis of accessory breast cancer should reference the TNM staging system for breast cancer; most accessory breast cancers are diagnosed at stages III and IV of the TNM staging system, with an average diagnostic delay of 40.5 months[3, 6, 17]. The diagnostic process includes a detailed medical history inquiry, physical examination, imaging examinations (ultrasound, mammography, MRI), and pathological diagnosis, among which pathology is the gold standard for accessory breast cancer diagnosis[1, 21]. Accessory breast cancer needs to be differentiated from common diseases such as lymphadenitis, lymph node tuberculosis, axillary tail breast cancer, lymph node metastatic carcinoma, and skin-derived tumors[18]. Anatomically, the scattered distribution of glandular tissue between the glands suggests that it does not originate from the thoracic wall mammary tissue[19]. Therefore, for accessory breast cancer, exclusion of metastatic carcinoma and sweat gland carcinoma, no connection with normal breast tissue, and the presence of normal breast tissue surrounding the cancerous tissue are all important indicators for diagnosis[1]. If large ducts are observed in the mammary tissue adjacent to the cancer, axillary tail breast cancer can be ruled out[10]. Imaging Studies Ultrasound is the preferred non-invasive examination for accessory breast cancer, primarily manifesting as a hypoechoic mass in the axilla with non-uniform internal echoes, indistinct borders, visible blood flow within the lesion, and a crab-leg-like margin[1, 6, 10, 15, 17]. In this case, both the initial and recurrent ultrasound examinations revealed an axillary hypoechoic mass with an irregular shape and non-uniform internal echoes, consistent with the common ultrasound features of accessory breast cancer. Mammography can identify microcalcifications and solid masses and is also recommended for the diagnosis of accessory breast cancer. However, due to the high position of the axilla, complex tissue structures, and overlapping tissues, mammography has low diagnostic sensitivity for accessory breast cancer in the axillary region[12]. In mammography, accessory breast cancer appears as a calcified lesion with indistinct borders and spiculations, but no obvious abnormalities were observed in the mammograms of both breasts for this patient[16, 19]. MRI excels in soft tissue contrast, clearly demonstrating the difference between normal and pathological tissues. Some studies suggest performing MRI on patients suspected of malignant transformation of the accessory breast, but MRI is time-consuming and expensive, and its value for accessory breast cancer is still controversial. It can be used to rule out ipsilateral primary breast cancer, determine tumor size and extent to guide surgical planning[7]. After local recurrence, this patient underwent right shoulder joint MRI, which showed high signal intensity in the accessory breast cancer, showing a marked contrast with the surrounding soft tissues, which was of diagnostic significance. In addition, the patient also underwent PET/CT, and both lesions were manifested as axillary masses with increased radioactive uptake, with no distant metastasis observed. Pathological Examination Pathology is the gold standard for the diagnosis of accessory breast cancer. Overall, the most common histological type of accessory breast cancer is invasive ductal carcinoma of no special type, accounting for approximately 72%, followed by medullary carcinoma, lobular carcinoma, mucinous carcinoma, apocrine carcinoma, papillary carcinoma, and cyst sarcoma phyllodes, which is similar to primary breast cancer[3, 6-8, 20]. Male accessory breast cancer itself has no specific immunohistochemical markers, and markers such as ER, PR, and HER2 are typically only used to guide treatment and predict prognosis[1, 6]. The pathological diagnosis of this patient was mucinous carcinoma, which has not been reported in the literature to date. In terms of immunohistochemistry, both of this patient's accessory breast cancers were hormone receptor-positive, with high Ki-67 expression and Her-2 (1-2+), making it difficult to distinguish from primary breast cancer based solely on immunohistochemistry. In addition, other studies have found that 78% of accessory breast cancer patients express CEA antigen, whereas 92% of primary breast cancer patients do not, which may be one of the breakthrough points for the diagnosis of accessory breast cancer[22]. Treatment The treatment of accessory breast cancer should refer to the concurrent treatment of breast cancer. If clinically judged as an early-stage tumor with no clear signs of regional lymph node metastasis, the preferred treatment method is wide local excision plus regional lymph node staging surgery, followed by radiotherapy, chemotherapy, endocrine therapy, etc., based on tumor type, stage, hormone receptor status, lymph node metastasis status, and other factors[17, 21, 23-25]. Surgical Treatment Regarding the axilla, the lymph node status may be a prognostic factor for male accessory breast cancer, however, because the lymphatic pathways of accessory breast cancer are not yet clear, SLNB (sentinel lymph node biopsy) is very important[1]. However, 20-30% of accessory breast cancer patients will have involved SLN (sentinel lymph nodes), and the SLN are difficult to identify, therefore some surgeons recommend axillary dissection as part of the initial surgery, especially for patients with axillary accessory breast cancer[12, 15]. Lymphography and SLNB are important for the axillary treatment of accessory breast cancer. The difficulty of SLNB lies in locating the SLN[26]. SLNB usually requires the injection of a tracer, and common tracers include methylene blue and radionuclides. For breast cancer patients, the sentinel node is often injected in the nipple-areola area, but the injection site for the accessory breast cancer is currently still controversial. Most reports favor injecting the radionuclide around the tumor, but a high count at the injection site may obscure the actual lymph node[24]. Harris used three injection sites: one intradermal injection into the skin directly above the tumor, one injection into the tumor itself, and one injection into the subcutaneous tissue behind the tumor. This method allows the tracer to reach the SLN through multiple pathways with lower radiation and no need for methylene blue, but it should be noted that the probe should be placed away from the injection site and directed towards the axillary area[24]. Some studies also use dual-tracer lymph node localization, injecting radionuclide in the areolar area preoperatively and methylene blue in the tumor[12]. The patient's first biopsy pathology showed right axillary lymph node involvement, so SLNB was not suitable and axillary lymph node dissection was performed directly. In summary, regarding the axillary lymph node management for patients with accessory breast cancer, SLNB should be performed first. Methods such as multi-point tracer injection or dual-tracer can be used to increase the detection rate of SLN. If SLNB fails or there is clear evidence of axillary lymph node metastasis, axillary lymph node dissection should be performed directly. In terms of the breast, Evans conducted a review of 17 cases of patients with accessory breast cancer and analyzed their treatment methods, finding that radical surgery or modified radical surgery did not improve patient survival rates compared to receiving accessory breast local excision + axillary lymph node dissection or radiotherapy[23]. Therefore, if preoperative examination rules out additional breast lesions or if the accessory breast cancer is located far from the breast, patients with accessory breast cancer can avoid ipsilateral mastectomy but should be closely followed up[2, 6, 15, 21]. If the patient has breast risk factors or is unable to undergo close follow-up, prophylactic ipsilateral breast resection should be performed[16]. Hao reported 2 cases of accessory breast cancer complicated with bilateral breast cancer. These patients ultimately underwent bilateral breast resection, accessory breast resection, adjacent pectoralis muscle resection, and axillary lymph node dissection[4]. In the current case, no bilateral breast lesions were seen on preoperative examination, so only accessory breast resection was performed, and no residual cancer was found in the surgical margins. During the second surgical treatment, the preoperative examination for the patient considered a single mass in the right axilla, with no breast lesions seen. Moreover, 4 years prior, the patient had already undergone right axillary lymph node dissection. Therefore, only right axillary tumor resection was performed. Adjuvant Therapy Systemic adjuvant therapy is equally important for patients with accessory breast cancer, and its adjuvant therapy is the same as traditional breast cancer[6]. Studies have shown that the prognosis of accessory breast cancer patients who receive standard systemic adjuvant therapy is comparable to that of traditional breast cancer[16]. If the accessory breast cancer is large preoperatively, neoadjuvant chemotherapy or endocrine therapy can also be used first, followed by surgery after the tumor shrinks[15]. Yamamura once reported a case of male accessory breast cancer with neoadjuvant therapy, the patient's tumor shrank from 85mm to 55mm after receiving 6 cycles of FEC neoadjuvant therapy, and the surgery was successfully performed[27]. The chemoradiotherapy regimens for male accessory breast cancer are the same as for female breast cancer. For locally advanced accessory breast cancer, anthracycline and taxane chemotherapeutic drugs are generally used[14, 20]. Bi reported a case of a male patient with axillary accessory breast cancer whose condition was successfully controlled by endocrine therapy (anastrozole, goserelin)[11]. Routiot believes that postoperative radiotherapy is needed at the tumor site to reduce the local recurrence rate, with a minimum radiotherapy dose of 50Gy and an additional 20Gy is required if the tumor involves the muscle or the margin is positive[2]. For patients who cannot tolerate surgery or refuse surgery, radiotherapy can also achieve local control with fewer side effects, but it is not routine to irradiate the ipsilateral breast[1, 15, 20]. This patient underwent “right accessory mastectomy + right axillary lymph node dissection”. Intraoperative frozen section and postoperative paraffin pathology both showed negative margins. Postoperative pathology showed positive hormone receptors. Because the patient's accessory breast cancer was large and there was lymph node involvement, 6 cycles of capecitabine treatment were given postoperatively, followed by anastrozole to date. No recurrence or metastasis was observed 3.5 years after surgery, reflecting the effectiveness of adjuvant therapy for accessory breast cancer. This year, the patient experienced local recurrence of accessory breast cancer and again underwent a right axillary expanded tumor resection. During the operation, the wound was soaked with 50mg cisplatin + 300ml hot distilled water for 10 minutes to kill tumor cells and reduce the postoperative recurrence rate. Subsequently, we switched to endocrine therapy with a CDK4/6 inhibitor + anastrozole. Prognosis Due to the limited number of relevant cases, more data are needed to supplement information on the prognosis of accessory breast cancer. Some studies suggest that the prognosis of accessory breast cancer is comparable to that of breast cancer with the same TNM staging, however, there are differing opinions suggesting that accessory breast cancer has a worse prognosis compared to conventional breast cancer, as accessory breast cancer often presents with early axillary lymph node metastasis[2, 6, 17, 21]. Previous studies found that among 27 patients with accessory breast cancer who underwent axillary dissection, 59% had lymph node metastasis, whereas only 51% of patients with tumors in the upper outer quadrant of the breast had lymph node metastasis[2]. Nihon analyzed lymph node involvement in 94 patients with accessory breast cancer and found an axillary lymph node metastasis rate of 51.8%, although there was no significant difference in lymph node involvement among different T stages of accessory breast cancer[19]. EVANS reported an analysis of 90 cases of accessory breast cancer, revealing an overall survival rate of 9.4% after treatment. Among 42 patients with follow-up records, only 28 patients survived beyond 1 year, and among these 28 patients, 12 patients experienced recurrence during follow-up[23]. In retrospective studies, patients who received standardized treatment primarily based on surgery had relatively favorable overall survival rates; the 5-year survival rate for accessory breast cancer patients at the Cancer Hospital, Chinese Academy of Medical Sciences was 41.7%, and at Tianjin Cancer Hospital it was 35.3%, though the number of included cases was small, with only 4 cases[15]. Wang et al. analyzed 22 patients with accessory breast cancer and calculated a 3-year disease-free survival rate of 63.4%[10]. Nihon followed up 68 patients with accessory breast cancer (mean follow-up time 28.3 months), and during the follow-up period, only 1 patient died of pneumonia[19]. Since current follow-up data are all derived from small sample analyses with considerable variation, large-sample follow-up data are needed to support prognostic analysis of accessory breast cancer. This article shares the diagnosis and treatment process of a 72-year-old male patient with mucinous carcinoma of the accessory breast, discusses and analyzes the relevant diagnosis and treatment of accessory breast cancer, with the aim of improving clinicians' understanding of male accessory breast cancer. Declarations Acknowledgements We would like to express our gratitude to the patients for granting permission to publish this case report. Funding This research received no external funding. Conflict of interest The authors declare no conflicts of interest. Author contribution Junying Huang: Writing-original draft, Writing-review & editing. Xingtong Zhou: Resources, Project administration, Conceptualization, Supervision; Xi Zhou: Writing-review & editing, Data curation. Data availability The datasets used and/or analyzed during the current study are availed from the corresponding author on reasonable request. Ethical approval and Consent to participate This study protocol was reviewed and approved by the ethics committee of Peking Union Medical College Hospital and this study complied with the Declaration of Helsinki. The patients provided their written informed consent to participate in this study. Consent to publish declaration Written informed consent was obtained from the patient for the publication of the present case report and any accompanying images. References Pang L, Cui M, Dai W, Wu S, Kong J: Diagnosis and Treatment of Male Accessory Breast Cancer: A Comprehensive Systematic Review . Front Oncol 2021, 11 :640000. Routiot T, Marchal C, Verhaeghe JL, Depardieu C, Netter E, Weber B, Carolus JM: Breast carcinoma located in ectopic breast tissue: a case report and review of the literature . Oncol Rep 1998, 5 (2):413-417. 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Mandal S, Bethala MG, Dadeboyina C, Khadka S, Kasireddy V: A Rare Presentation of an Invasive Ductal Carcinoma of Ectopic Axillary Breast Tissue . Cureus 2020, 12 (8):e9928. Wick MR, Ockner DM, Mills SE, Ritter JH, Swanson PE: Homologous carcinomas of the breasts, skin, and salivary glands. A histologic and immunohistochemical comparison of ductal mammary carcinoma, ductal sweat gland carcinoma, and salivary duct carcinoma . Am J Clin Pathol 1998, 109 (1):75-84. Evans DM, Guyton DP: Carcinoma of the axillary breast . J Surg Oncol 1995, 59 (3):190-195. Harris MK, Guo MZ, Mangino A, Taylor C, Carson WE: Sentinel node mapping and biopsy in ectopic axillary breast cancer: A case report and review of the literature . Clin Case Rep 2022, 10 (9):e6052. Fracchioli S, Puopolo M, De La Longrais IA, Scozzafava M, Bogliatto F, Arisio R, Micheletti L, Katsaros D: Primary \"breast-like\" cancer of the vulva: a case report and critical review of the literature . Int J Gynecol Cancer 2006, 16 Suppl 1 :423-428. Thorne AL, Jackson A, Yiangou C: The use of sentinel node biopsy in the treatment of cancer of an accessory breast . Breast 2003, 12 (2):153-155. Yamamura J, Masuda N, Kodama Y, Yasojima H, Mizutani M, Kuriyama K, Mano M, Nakamori S, Sekimoto M: Male breast cancer originating in an accessory mammary gland in the axilla: a case report . Case Rep Med 2012, 2012 :286210. Additional Declarations No competing interests reported. Supplementary Files CAREchecklistEnglish2013.pdf Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 06 Feb, 2026 Reviews received at journal 01 Feb, 2026 Reviews received at journal 18 Jan, 2026 Reviewers agreed at journal 14 Jan, 2026 Reviewers agreed at journal 13 Jan, 2026 Reviewers agreed at journal 28 Dec, 2025 Reviewers invited by journal 26 Dec, 2025 Editor invited by journal 24 Dec, 2025 Editor assigned by journal 11 Dec, 2025 Submission checks completed at journal 11 Dec, 2025 First submitted to journal 11 Dec, 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. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {\"props\":{\"pageProps\":{\"initialData\":{\"identity\":\"rs-8297190\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":false,\"archivedVersions\":[],\"articleType\":\"Case Report\",\"associatedPublications\":[],\"authors\":[{\"id\":566488610,\"identity\":\"c1bcd4ee-af71-4615-a115-6d8d8f5743eb\",\"order_by\":0,\"name\":\"Junying Huang\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Peking Union Medical College Hospital\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Junying\",\"middleName\":\"\",\"lastName\":\"Huang\",\"suffix\":\"\"},{\"id\":566488611,\"identity\":\"720d1062-5556-4a0a-8310-912b28c028bd\",\"order_by\":1,\"name\":\"Xi 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13:32:18\",\"extension\":\"xml\",\"order_by\":14,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"acdc-reference\",\"size\":76978,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"b2d824c9a48b43ac9c7b03da13673a571structuring.xml\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8297190/v1/e2299fabd5774764b95d0606.xml\"},{\"id\":99620021,\"identity\":\"951b0f41-cb85-48b6-9069-6a3c2849bcb0\",\"added_by\":\"auto\",\"created_at\":\"2026-01-06 14:08:01\",\"extension\":\"html\",\"order_by\":15,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"acdc-reference\",\"size\":83880,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"earlyproof.html\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8297190/v1/11b90b658df52bd9df29c666.html\"},{\"id\":99620001,\"identity\":\"649a005d-22cf-45dc-8046-9a99556c4cae\",\"added_by\":\"auto\",\"created_at\":\"2026-01-06 14:08:01\",\"extension\":\"png\",\"order_by\":1,\"title\":\"Figure 1\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":573265,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eFigure 1-2: Initial Ultrasonography revealed a hypoechoic mass in the right axilla, measuring approximately 4.9 × 3.3 × 3.6 cm. The lesion demonstrated a slightly irregular morphology with relatively well-defined margins. Internal echogenicity was heterogeneous, with the presence of anechoic areas. Color Doppler imaging showed linear vascularity within the mass.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage1.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8297190/v1/83e52e3c63c3cef20ae15923.png\"},{\"id\":99793865,\"identity\":\"acf3beec-4d9a-453c-aeaf-11e90ffeaa28\",\"added_by\":\"auto\",\"created_at\":\"2026-01-08 13:33:24\",\"extension\":\"png\",\"order_by\":2,\"title\":\"Figure 2\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":402260,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eFigure 3: Preoperative ultrasonography at recurrence revealed a 4.9 × 3.3 × 2.5 cm hypoechoic mass in the right axilla with irregular margins and internal blood flow.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage2.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8297190/v1/3ea3a505281a85af9b03b1a6.png\"},{\"id\":99620004,\"identity\":\"7b3273dc-b8ac-4639-a783-8670386e6b48\",\"added_by\":\"auto\",\"created_at\":\"2026-01-06 14:08:01\",\"extension\":\"png\",\"order_by\":3,\"title\":\"Figure 3\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":442038,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eFigure 4: Preoperative MRI at recurrence revealed a mass-like hyperintense signal was observed in the right axilla, measuring approximately 49×36 mm.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage3.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8297190/v1/62f0e8fd4cd47a4eb22f7911.png\"},{\"id\":99620013,\"identity\":\"60a051a5-2a02-4bce-b0cd-b319c9e19bcd\",\"added_by\":\"auto\",\"created_at\":\"2026-01-06 14:08:01\",\"extension\":\"png\",\"order_by\":4,\"title\":\"Figure 4\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":1068059,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eFigure 5: Preoperative PET/CT at recurrence can see a slightly hypodense lesion was observed within the right shoulder muscles, with mildly increased radiotracer uptake, measuring 2.9×2.5 cm, SUVmax 2.8. Malignancy cannot be excluded.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage4.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8297190/v1/ed31f95008f2173aa0f61bdb.png\"},{\"id\":99795042,\"identity\":\"ed7d9bc1-dd2e-44cc-9d63-fe311a1c6f24\",\"added_by\":\"auto\",\"created_at\":\"2026-01-08 13:36:52\",\"extension\":\"png\",\"order_by\":5,\"title\":\"Figure 5\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":994839,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eFigure 6-8: Intraoperative specimen description. The locally recurrent tumor of the right axillary accessory breast carcinoma presented with well-defined borders, measuring approximately 5 cm in maximum diameter. It was a solid tumor with a white cut surface, lobulated appearance, and irregular morphology. Intraoperatively, the tumor was observed to be in close proximity to the main axillary vein.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage5.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8297190/v1/b5ef313b58b2839724fccfbb.png\"},{\"id\":99804532,\"identity\":\"01216af5-b1e6-41de-8fed-5dc4cdfcc6a7\",\"added_by\":\"auto\",\"created_at\":\"2026-01-08 14:13:47\",\"extension\":\"pdf\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":5446588,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"manuscript.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8297190/v1/e9e6f72d-ae9c-4815-8fa1-6ed67edda72c.pdf\"},{\"id\":99793591,\"identity\":\"867c30ab-00d7-4133-8460-53ecfc64872e\",\"added_by\":\"auto\",\"created_at\":\"2026-01-08 13:31:55\",\"extension\":\"pdf\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"supplement\",\"size\":794172,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"CAREchecklistEnglish2013.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-8297190/v1/bc1006922ba846a0d44bbd78.pdf\"}],\"financialInterests\":\"No competing interests reported.\",\"formattedTitle\":\"Male Accessory Breast Mucinous Carcinoma: A Case Report and Literature Review\",\"fulltext\":[{\"header\":\"Introduction\",\"content\":\"\\u003cp\\u003eAccessory breast, also referred to as ectopic breast, constitutes residual breast tissue resulting from incomplete regression along the embryonic milk line. It has an estimated incidence of 2–6% and affects males and females at a ratio of 1:5, with a hereditary predisposition noted in some cases[\\u003cspan additionalcitationids=\\\"CR2\\\" citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e1\\u003c/span\\u003e–\\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e3\\u003c/span\\u003e]. At the 6th week of embryonic development, a milk line extending from the axilla to the groin appears. Except for the chest area, the milk line at other sites gradually disappears and the undissolved part is called accessory breast[\\u003cspan citationid=\\\"CR4\\\" class=\\\"CitationRef\\\"\\u003e4\\u003c/span\\u003e]. Approximately 90% of accessory breasts are located along this milk line, with the remaining 10% found in extramammary locations such as the back, limbs, face, and neck[\\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e3\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e5\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR6\\\" class=\\\"CitationRef\\\"\\u003e6\\u003c/span\\u003e]. Like normal breast tissue, accessory breast can be affected by hormones to produce corresponding physiological changes and common primary breast tumors, such as fibroadenoma, breast cancer, and phyllodes tumors[\\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e3\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR7\\\" class=\\\"CitationRef\\\"\\u003e7\\u003c/span\\u003e]. The first documented case of accessory breast carcinoma was reported in 1861, followed by the first reported case in a male patient in 1957[\\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e1\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR8\\\" class=\\\"CitationRef\\\"\\u003e8\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e9\\u003c/span\\u003e]. Accessory breast cancer is a primary malignant tumor originating from the epithelial tissue of the accessory breast, accounting for about 0.3–0.6% of all breast cancers, with a male to female ratio of 1:12.4[\\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e5\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR10\\\" class=\\\"CitationRef\\\"\\u003e10\\u003c/span\\u003e]. Accessory breast cancer can occur at any position along the milk line, but it is more common in the axilla and groin; This predilection may be attributed to the rich vascular and lymphatic networks in these regions, which may also contribute to the typically aggressive clinical course, including a propensity for early metastasis[\\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e11\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR12\\\" class=\\\"CitationRef\\\"\\u003e12\\u003c/span\\u003e]. This case report details a 72-year-old male patient with axillary accessory breast cancer initially diagnosed four years prior, who presented with a local recurrence in 2025. Both the initial diagnosis and subsequent management were performed at our institution. We present this rare case to summarize the clinical characteristics, diagnostic approach, therapeutic management, and prognostic considerations associated with accessory breast carcinoma, supplemented by a review of the relevant literature.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e\"},{\"header\":\"Case Presentation\",\"content\":\"\\u003cp\\u003eThe patient was a 72-year-old male who presented to our hospital in December 2021 with a right axillary mass that had been present for two years. Physical examination revealed a prominent right axillary mass on the body surface, with a size of approximately 3.0x4.0 cm. The skin over the mass showed no abnormalities, and no significant abnormalities were observed in both breasts. Auxiliary examinations: ultrasound indicated a hypoechoic lesion measuring 4.9x3.3x3.6 cm with a slightly irregular shape, relatively clear borders, heterogeneous internal echoes containing anechoic areas, and visible linear blood flow (Figures 1-2); mammography showed no significant abnormalities. To confirm the pathology, the patient underwent a \\u0026quot;right axillary mass excisional biopsy\\u0026quot; at our hospital. The postoperative pathology report stated: (right axillary lymph node) a cancer nodule was seen, consistent with breast mucinous carcinoma, not excluding an accessory breast origin, ER (strong positive, 85%), PR (moderate to strong positive, 50%), Her-2 (2+), Ki-67 (10%).\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003ePostoperatively, the patient underwent further PET/CT: multiple lymph nodes with increased radiotracer uptake were seen in the right axilla, the largest measuring approximately 3.0x4.0 cm, SUVmax 7.3, suggestive of a malignant lesion; no abnormal metabolic foci were seen in both breasts. Our hospital performed a \\u0026quot;right accessory breast resection + right axillary lymph node dissection\\u0026quot; on the patient. The postoperative paraffin pathology report stated: (right accessory breast and axillary lympho-fatty tissue) invasive breast carcinoma (no special type, partially mucinous carcinoma, moderately differentiated, size 4x3.5x2.5 cm), lymph nodes showed chronic inflammation (0/25); ER (strong positive, 95%), PR (moderate positive, 80%), Her-2 (1+), Ki-67 (40%). Postoperatively, the patient received six cycles of adjuvant capecitabine chemotherapy, followed by maintenance anastrozole endocrine therapy. Regular follow-ups during this period showed no recurrence or metastasis (the last follow-up breast and axillary ultrasound was in April 2025, which was unremarkable at that time).\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003eIn June 2025, the patient palpated a mass of about 4 cm near the right axillary incision, close to the medial side of the upper arm, which was hard, relatively fixed, without significant tenderness and accompanied by mild edema of the right upper limb. An ultrasound (2025-7-17) revealed a hypoechoic lesion in the right axilla, approximately 4.9x3.3x2.5 cm in size, with an irregular shape, relatively clear borders, and visible blood flow within (Figure 3); MRI: a mass-like high-signal intensity was seen in the right axilla, measuring approximately 49x36 mm (Figure 4). A PET/CT was completed: a slightly low-density lesion with slightly increased radiotracer uptake was seen in the right shoulder muscle, measuring 2.9x2.5 cm, SUVmax 2.8, which needed to exclude the possibility of malignancy, with no distant metastasis seen (Figure 5). The patient subsequently underwent a \\u0026ldquo;right axillary mass needle biopsy\\u0026rdquo; and the biopsy pathology was metastatic breast mucinous carcinoma. In September 2025, the patient underwent a \\u0026ldquo;wide excision of the right axillary tumor\\u0026rdquo; at our hospital again. Intraoperatively, a red-white tumor was found within the coracobrachialis muscle under the right axillary scar, which was hard, approximately 5x4x3 cm in size, lobulated, with relatively clear borders, and the tumor was close to the main axillary artery and vein (Figures 6-8). During the operation, the wound was soaked with 50 mg cisplatin + 300 ml of hot distilled water for 10 minutes. Postoperative pathology indicated (right axillary tumor) metastatic breast mucinous carcinoma, ER (strong positive, 90%), PR (strong positive, 90%), Her-2 (2+), Ki-67 50%. Combined with the patient\\u0026apos;s previous medical history, it is now considered that the patient has local recurrence of accessory breast carcinoma. Postoperatively, based on the pathology, the endocrine therapy regimen was changed to a CDK4/6 inhibitor + anastrozole.\\u003c/p\\u003e\"},{\"header\":\"Discussion\",\"content\":\"\\u003cp\\u003eBreast cancer is one of the most common malignant tumors among women worldwide, with male breast cancer accounting for less than 1% and accessory breast cancer accounting for 0.3-0.6%, while only 0.2-1.2% of men have accessory breasts[13, 14]. Consequently, male accessory breast cancer is exceptionally uncommon, and current literature is limited to sporadic case reports and small retrospective studies due to insufficient large-scale statistical data. The etiology of accessory breast cancer is unclear, and some studies suggest that risk factors closely related to breast cancer may also induce supernumerary breast cancer, such as genetic factors, enhanced estrogen or estrogen-androgen imbalance, and environmental influences (electromagnetic fields, high temperature, formaldehyde, etc.)[15].\\u003c/p\\u003e\\n\\u003cp\\u003eEpidemiology and Clinical Presentation\\u003c/p\\u003e\\n\\u003cp\\u003eThe age at diagnosis for accessory breast cancer ranges from 28 to 90 years, with a peak incidence between 40 and 45 years, accounting for about 50% of all cases[6]. Pang et al. analyzed 16 cases of male accessory breast cancer patients, finding that most were Asian, with ages ranging from 51 to 87 years and an average age of 67.1 years[1]. Early-stage accessory breast cancer is typically asymptomatic. As the tumor progresses, it typically presents as a firm, poorly defined and irregularly shaped mass within the accessory breast tissue with an average diameter of 2.8 cm; Some patients may experience accompanying pain and swelling, when the surface of the mass is involved, it can appear light red, purplish-red, or exhibit an orange peel appearance, ulcers or purulent discharge may occur in severe cases. Most patients seek medical attention only when clear symptoms are present, which typically occurs long after the disease has onset, leading to delays in treatment[1, 6, 16-19]. Furthermore, the clinical presentation of accessory breast cancer is not specific and is difficult to distinguish from benign axillary masses (such as lipomas, tuberculous lymphadenitis, reactive lymphadenopathy) or malignant masses (such as lymph node metastatic carcinoma, appendageal tumors). Studies have found that 58% of accessory breast cancers occur in the axilla, 18.5% in the parasternal region, 6.8% in the subclavian area, 8.6% in the sub mammary region, and 4% in the vulva[8]. Accessory breast cancer in the axilla is often accompanied by enlarged and fused ipsilateral axillary or supraclavicular lymph nodes. Accessory breast cancer in the groin region can also involve enlarged and fused ipsilateral inguinal lymph nodes. Regarding metastasis, 50% of patients with accessory breast cancer already exhibit axillary lymph node metastasis at the time of initial diagnosis[12, 18]. Accessory breast cancer can also lead to invasion and metastasis to adjacent organs, such as thoracic, cerebellar, and bone metastases, but these typically occur in the later stages of the disease[1]. In summary, accessory breast cancer most commonly metastasizes to the ipsilateral axillary lymph nodes, followed by metastasis to the supraclavicular lymph nodes. Therefore, some studies suggest that when internal mammary lymph node metastasis is present, it should be considered as M1 (distant metastasis) rather than N1-2 (regional lymph node metastasis)[6, 20]. In the case of this patient, the 72-year-old elderly male presented with a firm, approximately 4 cm mass in the right axilla during both visits. The overlying skin showed no obvious involvement, and the patient had no significant accompanying symptoms, which is consistent with the clinical presentation of accessory breast cancer. The presence of metastatic cancer nodules in the right axillary lymph nodes at the time of the first visit confirms the tendency for axillary accessory breast cancer to develop lymph node metastases early in the disease course. The right upper limb edema observed during the second recurrence was likely a result of impaired lymphatic drainage caused by the combination of a previous axillary lymph node dissection and the current axillary tumor burden.\\u003c/p\\u003e\\n\\u003cp\\u003eDiagnosis\\u003c/p\\u003e\\n\\u003cp\\u003eDue to its rarity, the diagnosis of male accessory breast cancer is extremely difficult. The diagnosis of accessory breast cancer should reference the TNM staging system for breast cancer; most accessory breast cancers are diagnosed at stages III and IV of the TNM staging system, with an average diagnostic delay of 40.5 months[3, 6, 17]. The diagnostic process includes a detailed medical history inquiry, physical examination, imaging examinations (ultrasound, mammography, MRI), and pathological diagnosis, among which pathology is the gold standard for accessory breast cancer diagnosis[1, 21]. Accessory breast cancer needs to be differentiated from common diseases such as lymphadenitis, lymph node tuberculosis, axillary tail breast cancer, lymph node metastatic carcinoma, and skin-derived tumors[18]. Anatomically, the scattered distribution of glandular tissue between the glands suggests that it does not originate from the thoracic wall mammary tissue[19]. Therefore, for accessory breast cancer, exclusion of metastatic carcinoma and sweat gland carcinoma, no connection with normal breast tissue, and the presence of normal breast tissue surrounding the cancerous tissue are all important indicators for diagnosis[1]. If large ducts are observed in the mammary tissue adjacent to the cancer, axillary tail breast cancer can be ruled out[10].\\u003c/p\\u003e\\n\\u003cp\\u003eImaging Studies\\u003c/p\\u003e\\n\\u003cp\\u003eUltrasound is the preferred non-invasive examination for accessory breast cancer, primarily manifesting as a hypoechoic mass in the axilla with non-uniform internal echoes, indistinct borders, visible blood flow within the lesion, and a crab-leg-like margin[1, 6, 10, 15, 17]. In this case, both the initial and recurrent ultrasound examinations revealed an axillary hypoechoic mass with an irregular shape and non-uniform internal echoes, consistent with the common ultrasound features of accessory breast cancer. Mammography can identify microcalcifications and solid masses and is also recommended for the diagnosis of accessory breast cancer. However, due to the high position of the axilla, complex tissue structures, and overlapping tissues, mammography has low diagnostic sensitivity for accessory breast cancer in the axillary region[12]. In mammography, accessory breast cancer appears as a calcified lesion with indistinct borders and spiculations, but no obvious abnormalities were observed in the mammograms of both breasts for this patient[16, 19]. MRI excels in soft tissue contrast, clearly demonstrating the difference between normal and pathological tissues. Some studies suggest performing MRI on patients suspected of malignant transformation of the accessory breast, but MRI is time-consuming and expensive, and its value for accessory breast cancer is still controversial. It can be used to rule out ipsilateral primary breast cancer, determine tumor size and extent to guide surgical planning[7]. After local recurrence, this patient underwent right shoulder joint MRI, which showed high signal intensity in the accessory breast cancer, showing a marked contrast with the surrounding soft tissues, which was of diagnostic significance. In addition, the patient also underwent PET/CT, and both lesions were manifested as axillary masses with increased radioactive uptake, with no distant metastasis observed.\\u003c/p\\u003e\\n\\u003cp\\u003ePathological Examination\\u003c/p\\u003e\\n\\u003cp\\u003ePathology is the gold standard for the diagnosis of accessory breast cancer. Overall, the most common histological type of accessory breast cancer is invasive ductal carcinoma of no special type, accounting for approximately 72%, followed by medullary carcinoma, lobular carcinoma, mucinous carcinoma, apocrine carcinoma, papillary carcinoma, and cyst sarcoma phyllodes, which is similar to primary breast cancer[3, 6-8, 20]. Male accessory breast cancer itself has no specific immunohistochemical markers, and markers such as ER, PR, and HER2 are typically only used to guide treatment and predict prognosis[1, 6]. The pathological diagnosis of this patient was mucinous carcinoma, which has not been reported in the literature to date. In terms of immunohistochemistry, both of this patient\\u0026apos;s accessory breast cancers were hormone receptor-positive, with high Ki-67 expression and Her-2 (1-2+), making it difficult to distinguish from primary breast cancer based solely on immunohistochemistry.\\u003c/p\\u003e\\n\\u003cp\\u003eIn addition, other studies have found that 78% of accessory breast cancer patients express CEA antigen, whereas 92% of primary breast cancer patients do not, which may be one of the breakthrough points for the diagnosis of accessory breast cancer[22].\\u003c/p\\u003e\\n\\u003cp\\u003eTreatment\\u003c/p\\u003e\\n\\u003cp\\u003eThe treatment of accessory breast cancer should refer to the concurrent treatment of breast cancer. If clinically judged as an early-stage tumor with no clear signs of regional lymph node metastasis, the preferred treatment method is wide local excision plus regional lymph node staging surgery, followed by radiotherapy, chemotherapy, endocrine therapy, etc., based on tumor type, stage, hormone receptor status, lymph node metastasis status, and other factors[17, 21, 23-25].\\u003c/p\\u003e\\n\\u003cp\\u003eSurgical Treatment\\u003c/p\\u003e\\n\\u003cp\\u003eRegarding the axilla, the lymph node status may be a prognostic factor for male accessory breast cancer, however, because the lymphatic pathways of accessory breast cancer are not yet clear, SLNB (sentinel lymph node biopsy) is very important[1]. However, 20-30% of accessory breast cancer patients will have involved SLN (sentinel lymph nodes), and the SLN are difficult to identify, therefore some surgeons recommend axillary dissection as part of the initial surgery, especially for patients with axillary accessory breast cancer[12, 15]. Lymphography and SLNB are important for the axillary treatment of accessory breast cancer. The difficulty of SLNB lies in locating the SLN[26]. SLNB usually requires the injection of a tracer, and common tracers include methylene blue and radionuclides. For breast cancer patients, the sentinel node is often injected in the nipple-areola area, but the injection site for the accessory breast cancer is currently still controversial. Most reports favor injecting the radionuclide around the tumor, but a high count at the injection site may obscure the actual lymph node[24]. Harris used three injection sites: one intradermal injection into the skin directly above the tumor, one injection into the tumor itself, and one injection into the subcutaneous tissue behind the tumor. This method allows the tracer to reach the SLN through multiple pathways with lower radiation and no need for methylene blue, but it should be noted that the probe should be placed away from the injection site and directed towards the axillary area[24]. Some studies also use dual-tracer lymph node localization, injecting radionuclide in the areolar area preoperatively and methylene blue in the tumor[12]. The patient\\u0026apos;s first biopsy pathology showed right axillary lymph node involvement, so SLNB was not suitable and axillary lymph node dissection was performed directly. In summary, regarding the axillary lymph node management for patients with accessory breast cancer, SLNB should be performed first. Methods such as multi-point tracer injection or dual-tracer can be used to increase the detection rate of SLN. If SLNB fails or there is clear evidence of axillary lymph node metastasis, axillary lymph node dissection should be performed directly.\\u003c/p\\u003e\\n\\u003cp\\u003eIn terms of the breast, Evans conducted a review of 17 cases of patients with accessory breast cancer and analyzed their treatment methods, finding that radical surgery or modified radical surgery did not improve patient survival rates compared to receiving accessory breast local excision + axillary lymph node dissection or radiotherapy[23]. Therefore, if preoperative examination rules out additional breast lesions or if the accessory breast cancer is located far from the breast, patients with accessory breast cancer can avoid ipsilateral mastectomy but should be closely followed up[2, 6, 15, 21]. If the patient has breast risk factors or is unable to undergo close follow-up, prophylactic ipsilateral breast resection should be performed[16]. Hao reported 2 cases of accessory breast cancer complicated with bilateral breast cancer. These patients ultimately underwent bilateral breast resection, accessory breast resection, adjacent pectoralis muscle resection, and axillary lymph node dissection[4]. In the current case, no bilateral breast lesions were seen on preoperative examination, so only accessory breast resection was performed, and no residual cancer was found in the surgical margins. During the second surgical treatment, the preoperative examination for the patient considered a single mass in the right axilla, with no breast lesions seen. Moreover, 4 years prior, the patient had already undergone right axillary lymph node dissection. Therefore, only right axillary tumor resection was performed.\\u003c/p\\u003e\\n\\u003cp\\u003eAdjuvant Therapy\\u003c/p\\u003e\\n\\u003cp\\u003eSystemic adjuvant therapy is equally important for patients with accessory breast cancer, and its adjuvant therapy is the same as traditional breast cancer[6]. Studies have shown that the prognosis of accessory breast cancer patients who receive standard systemic adjuvant therapy is comparable to that of traditional breast cancer[16]. If the accessory breast cancer is large preoperatively, neoadjuvant chemotherapy or endocrine therapy can also be used first, followed by surgery after the tumor shrinks[15]. Yamamura once reported a case of male accessory breast cancer with neoadjuvant therapy, the patient\\u0026apos;s tumor shrank from 85mm to 55mm after receiving 6 cycles of FEC neoadjuvant therapy, and the surgery was successfully performed[27]. The chemoradiotherapy regimens for male accessory breast cancer are the same as for female breast cancer. For locally advanced accessory breast cancer, anthracycline and taxane chemotherapeutic drugs are generally used[14, 20]. Bi reported a case of a male patient with axillary accessory breast cancer whose condition was successfully controlled by endocrine therapy (anastrozole, goserelin)[11]. Routiot believes that postoperative radiotherapy is needed at the tumor site to reduce the local recurrence rate, with a minimum radiotherapy dose of 50Gy and an additional 20Gy is required if the tumor involves the muscle or the margin is positive[2]. For patients who cannot tolerate surgery or refuse surgery, radiotherapy can also achieve local control with fewer side effects, but it is not routine to irradiate the ipsilateral breast[1, 15, 20]. This patient underwent \\u0026ldquo;right accessory mastectomy + right axillary lymph node dissection\\u0026rdquo;. Intraoperative frozen section and postoperative paraffin pathology both showed negative margins. Postoperative pathology showed positive hormone receptors. Because the patient\\u0026apos;s accessory breast cancer was large and there was lymph node involvement, 6 cycles of capecitabine treatment were given postoperatively, followed by anastrozole to date. No recurrence or metastasis was observed 3.5 years after surgery, reflecting the effectiveness of adjuvant therapy for accessory breast cancer. This year, the patient experienced local recurrence of accessory breast cancer and again underwent a right axillary expanded tumor resection. During the operation, the wound was soaked with 50mg cisplatin + 300ml hot distilled water for 10 minutes to kill tumor cells and reduce the postoperative recurrence rate. Subsequently, we switched to endocrine therapy with a CDK4/6 inhibitor + anastrozole.\\u003c/p\\u003e\\n\\u003cp\\u003ePrognosis\\u003c/p\\u003e\\n\\u003cp\\u003eDue to the limited number of relevant cases, more data are needed to supplement information on the prognosis of accessory breast cancer. Some studies suggest that the prognosis of accessory breast cancer is comparable to that of breast cancer with the same TNM staging, however, there are differing opinions suggesting that accessory breast cancer has a worse prognosis compared to conventional breast cancer, as accessory breast cancer often presents with early axillary lymph node metastasis[2, 6, 17, 21]. Previous studies found that among 27 patients with accessory breast cancer who underwent axillary dissection, 59% had lymph node metastasis, whereas only 51% of patients with tumors in the upper outer quadrant of the breast had lymph node metastasis[2]. Nihon analyzed lymph node involvement in 94 patients with accessory breast cancer and found an axillary lymph node metastasis rate of 51.8%, although there was no significant difference in lymph node involvement among different T stages of accessory breast cancer[19]. EVANS reported an analysis of 90 cases of accessory breast cancer, revealing an overall survival rate of 9.4% after treatment. Among 42 patients with follow-up records, only 28 patients survived beyond 1 year, and among these 28 patients, 12 patients experienced recurrence during follow-up[23]. In retrospective studies, patients who received standardized treatment primarily based on surgery had relatively favorable overall survival rates; the 5-year survival rate for accessory breast cancer patients at the Cancer Hospital, Chinese Academy of Medical Sciences was 41.7%, and at Tianjin Cancer Hospital it was 35.3%, though the number of included cases was small, with only 4 cases[15]. Wang et al. analyzed 22 patients with accessory breast cancer and calculated a 3-year disease-free survival rate of 63.4%[10]. Nihon followed up 68 patients with accessory breast cancer (mean follow-up time 28.3 months), and during the follow-up period, only 1 patient died of pneumonia[19]. Since current follow-up data are all derived from small sample analyses with considerable variation, large-sample follow-up data are needed to support prognostic analysis of accessory breast cancer.\\u003c/p\\u003e\\n\\u003cp\\u003eThis article shares the diagnosis and treatment process of a 72-year-old male patient with mucinous carcinoma of the accessory breast, discusses and analyzes the relevant diagnosis and treatment of accessory breast cancer, with the aim of improving clinicians\\u0026apos; understanding of male accessory breast cancer.\\u003c/p\\u003e\"},{\"header\":\"Declarations\",\"content\":\"\\u003cp\\u003eAcknowledgements\\u003c/p\\u003e\\n\\u003cp\\u003eWe would like to express our gratitude to the patients for granting permission to publish this case report.\\u003c/p\\u003e\\n\\u003cp\\u003eFunding\\u003c/p\\u003e\\n\\u003cp\\u003eThis research received no external funding.\\u003c/p\\u003e\\n\\u003cp\\u003eConflict of interest\\u003c/p\\u003e\\n\\u003cp\\u003eThe authors declare no conflicts of interest.\\u003c/p\\u003e\\n\\u003cp\\u003eAuthor contribution\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003eJunying Huang: Writing-original draft, Writing-review \\u0026amp; editing. Xingtong Zhou: Resources, Project administration, Conceptualization, Supervision; Xi Zhou: Writing-review \\u0026amp; editing, Data curation.\\u003c/p\\u003e\\n\\u003cp\\u003eData availability\\u003c/p\\u003e\\n\\u003cp\\u003eThe datasets used and/or analyzed during the current study are availed from the corresponding author on reasonable request.\\u003c/p\\u003e\\n\\u003cp\\u003eEthical approval and Consent to participate\\u003c/p\\u003e\\n\\u003cp\\u003eThis study protocol was reviewed and approved by the ethics committee of Peking Union Medical College Hospital and this study complied with the Declaration of Helsinki. The patients provided their written informed consent to participate in this study.\\u003c/p\\u003e\\n\\u003cp\\u003eConsent to publish declaration\\u003c/p\\u003e\\n\\u003cp\\u003eWritten informed consent was obtained from the patient for the publication of the present case report and any accompanying images.\\u003c/p\\u003e\"},{\"header\":\"References\",\"content\":\"\\u003col\\u003e\\n\\u003cli\\u003ePang L, Cui M, Dai W, Wu S, Kong J: \\u003cstrong\\u003eDiagnosis and Treatment of Male Accessory Breast Cancer: A Comprehensive Systematic Review\\u003c/strong\\u003e. \\u003cem\\u003eFront Oncol \\u003c/em\\u003e2021, \\u003cstrong\\u003e11\\u003c/strong\\u003e:640000.\\u003c/li\\u003e\\n\\u003cli\\u003eRoutiot T, Marchal C, Verhaeghe JL, Depardieu C, Netter E, Weber B, Carolus JM: \\u003cstrong\\u003eBreast carcinoma located in ectopic breast tissue: a case report and review of the literature\\u003c/strong\\u003e. \\u003cem\\u003eOncol Rep \\u003c/em\\u003e1998, \\u003cstrong\\u003e5\\u003c/strong\\u003e(2):413-417.\\u003c/li\\u003e\\n\\u003cli\\u003eGutermuth J, Audring H, Voit C, Haas N: \\u003cstrong\\u003ePrimary carcinoma of ectopic axillary breast tissue\\u003c/strong\\u003e. \\u003cem\\u003eJ Eur Acad Dermatol Venereol \\u003c/em\\u003e2006, \\u003cstrong\\u003e20\\u003c/strong\\u003e(2):217-221.\\u003c/li\\u003e\\n\\u003cli\\u003eHao JY, Yang CC, Liu FF, Yang YL, Li S, Li WD, Li YQ, Lang RG, Fan Y, Paulos E\\u003cem\\u003e et al\\u003c/em\\u003e: \\u003cstrong\\u003eAccessory breast cancer occurring concurrently with bilateral primary invasive breast carcinomas: a report of two cases and literature review\\u003c/strong\\u003e. \\u003cem\\u003eCancer Biol Med \\u003c/em\\u003e2012, \\u003cstrong\\u003e9\\u003c/strong\\u003e(3):197-201.\\u003c/li\\u003e\\n\\u003cli\\u003eKitamura K, Kuwano H, Kiyomatsu K, Ikejiri K, Sugimachi K, Saku M: \\u003cstrong\\u003eMastopathy of the accessory breast in the bilateral axillary regions occurring concurrently with advanced breast cancer\\u003c/strong\\u003e. \\u003cem\\u003eBreast Cancer Res Treat \\u003c/em\\u003e1995, \\u003cstrong\\u003e35\\u003c/strong\\u003e(2):221-224.\\u003c/li\\u003e\\n\\u003cli\\u003eVisconti G, Eltahir Y, Van Ginkel RJ, Bart J, Werker PM: \\u003cstrong\\u003eApproach and management of primary ectopic breast carcinoma in the axilla: where are we? 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A histologic and immunohistochemical comparison of ductal mammary carcinoma, ductal sweat gland carcinoma, and salivary duct carcinoma\\u003c/strong\\u003e. \\u003cem\\u003eAm J Clin Pathol \\u003c/em\\u003e1998, \\u003cstrong\\u003e109\\u003c/strong\\u003e(1):75-84.\\u003c/li\\u003e\\n\\u003cli\\u003eEvans DM, Guyton DP: \\u003cstrong\\u003eCarcinoma of the axillary breast\\u003c/strong\\u003e. \\u003cem\\u003eJ Surg Oncol \\u003c/em\\u003e1995, \\u003cstrong\\u003e59\\u003c/strong\\u003e(3):190-195.\\u003c/li\\u003e\\n\\u003cli\\u003eHarris MK, Guo MZ, Mangino A, Taylor C, Carson WE: \\u003cstrong\\u003eSentinel node mapping and biopsy in ectopic axillary breast cancer: A case report and review of the literature\\u003c/strong\\u003e. \\u003cem\\u003eClin Case Rep \\u003c/em\\u003e2022, \\u003cstrong\\u003e10\\u003c/strong\\u003e(9):e6052.\\u003c/li\\u003e\\n\\u003cli\\u003eFracchioli S, Puopolo M, De La Longrais IA, Scozzafava M, Bogliatto F, Arisio R, Micheletti L, Katsaros D: \\u003cstrong\\u003ePrimary \\u0026quot;breast-like\\u0026quot; cancer of the vulva: a case report and critical review of the literature\\u003c/strong\\u003e. \\u003cem\\u003eInt J Gynecol Cancer \\u003c/em\\u003e2006, \\u003cstrong\\u003e16 Suppl 1\\u003c/strong\\u003e:423-428.\\u003c/li\\u003e\\n\\u003cli\\u003eThorne AL, Jackson A, Yiangou C: \\u003cstrong\\u003eThe use of sentinel node biopsy in the treatment of cancer of an accessory breast\\u003c/strong\\u003e. \\u003cem\\u003eBreast \\u003c/em\\u003e2003, \\u003cstrong\\u003e12\\u003c/strong\\u003e(2):153-155.\\u003c/li\\u003e\\n\\u003cli\\u003eYamamura J, Masuda N, Kodama Y, Yasojima H, Mizutani M, Kuriyama K, Mano M, Nakamori S, Sekimoto M: \\u003cstrong\\u003eMale breast cancer originating in an accessory mammary gland in the axilla: a case report\\u003c/strong\\u003e. \\u003cem\\u003eCase Rep Med \\u003c/em\\u003e2012, \\u003cstrong\\u003e2012\\u003c/strong\\u003e:286210.\\u003c/li\\u003e\\n\\u003c/ol\\u003e\"}],\"fulltextSource\":\"\",\"fullText\":\"\",\"funders\":[],\"hasAdminPriorityOnWorkflow\":false,\"hasManuscriptDocX\":true,\"hasOptedInToPreprint\":true,\"hasPassedJournalQc\":\"\",\"hasAnyPriority\":false,\"hideJournal\":false,\"highlight\":\"\",\"institution\":\"\",\"isAcceptedByJournal\":true,\"isAuthorSuppliedPdf\":false,\"isDeskRejected\":\"\",\"isHiddenFromSearch\":false,\"isInQc\":false,\"isInWorkflow\":false,\"isPdf\":false,\"isPdfUpToDate\":true,\"isWithdrawnOrRetracted\":false,\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"discover-oncology\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":false,\"externalIdentity\":\"dion\",\"sideBox\":\"Learn more about [Discover Oncology](https://www.springer.com/12672)\",\"snPcode\":\"\",\"submissionUrl\":\"\",\"title\":\"Discover Oncology\",\"twitterHandle\":\"\",\"acdcEnabled\":true,\"dfaEnabled\":true,\"editorialSystem\":\"stoa\",\"reportingPortfolio\":\"Discover Series\",\"inReviewEnabled\":true,\"inReviewRevisionsEnabled\":true},\"keywords\":\"Accessory breast cancer, Male breast cancer, Case report\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-8297190/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-8297190/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"\\u003cp\\u003eAccessory breast cancer is a special type of breast cancer, accounting for approximately 0.3\\u0026ndash;0.6% of all breast cancers, of which male accessory breast cancer is even rarer. This condition typically manifests as a progressively enlarging mass, most frequently located in the axillary or inguinal regions, and may present with early lymph node metastasis. Pathological examination serves as the definitive diagnostic standard, while ultrasound, mammography and MRI are valuable ancillary diagnostic tools. Currently, the treatment for accessory breast cancer primarily references the treatment of breast cancer, employing surgical resection as the cornerstone of treatment, supplemented by endocrine therapy, chemotherapy, and radiotherapy. Here, we report a case of a 72-year-old male with accessory breast cancer. The patient was diagnosed with right axillary accessory breast cancer with right axillary lymph node metastatic cancer in 2021 and underwent right accessory mastectomy plus right axillary lymph node dissection at our hospital. Postoperatively, he has been supplemented with chemotherapy and endocrine therapy to this day. In 2025, a follow-up examination revealed a new mass in the medial aspect of the right upper arm near the axilla, and post-excisional pathology suggested it to be mucinous breast cancer. We aim to increase clinical awareness and understanding of male accessory breast cancer by detailing the discovery, clinical course, and management of this exceptionally rare case.\\u003c/p\\u003e\",\"manuscriptTitle\":\"Male Accessory Breast Mucinous Carcinoma: A Case Report and Literature Review\",\"msid\":\"\",\"msnumber\":\"\",\"nonDraftVersions\":[{\"code\":1,\"date\":\"2026-01-06 14:07:56\",\"doi\":\"10.21203/rs.3.rs-8297190/v1\",\"editorialEvents\":[{\"type\":\"communityComments\",\"content\":0},{\"type\":\"decision\",\"content\":\"Revision requested\",\"date\":\"2026-02-06T10:33:14+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2026-02-01T15:38:23+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2026-01-18T10:44:34+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"134259594462072222138173336331464818578\",\"date\":\"2026-01-14T13:13:42+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"72850866428452029739284472782775247481\",\"date\":\"2026-01-13T13:47:31+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"283347186448155570213616999786223066668\",\"date\":\"2025-12-28T21:43:38+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewersInvited\",\"content\":\"\",\"date\":\"2025-12-26T08:11:43+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorInvited\",\"content\":\"\",\"date\":\"2025-12-24T15:40:20+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorAssigned\",\"content\":\"\",\"date\":\"2025-12-12T03:45:55+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"checksComplete\",\"content\":\"\",\"date\":\"2025-12-11T09:58:54+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"submitted\",\"content\":\"Discover Oncology\",\"date\":\"2025-12-11T09:12:04+00:00\",\"index\":\"\",\"fulltext\":\"\"}],\"status\":\"published\",\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"discover-oncology\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":false,\"externalIdentity\":\"dion\",\"sideBox\":\"Learn more about [Discover Oncology](https://www.springer.com/12672)\",\"snPcode\":\"\",\"submissionUrl\":\"\",\"title\":\"Discover Oncology\",\"twitterHandle\":\"\",\"acdcEnabled\":true,\"dfaEnabled\":true,\"editorialSystem\":\"stoa\",\"reportingPortfolio\":\"Discover Series\",\"inReviewEnabled\":true,\"inReviewRevisionsEnabled\":true}}],\"origin\":\"\",\"ownerIdentity\":\"3f0997ea-5411-4441-b6ee-db86e66024e8\",\"owner\":[],\"postedDate\":\"January 6th, 2026\",\"published\":true,\"recentEditorialEvents\":[],\"rejectedJournal\":[],\"revision\":\"\",\"amendment\":\"\",\"status\":\"under-review\",\"subjectAreas\":[],\"tags\":[],\"updatedAt\":\"2026-03-10T22:23:55+00:00\",\"versionOfRecord\":[],\"versionCreatedAt\":\"2026-01-06 14:07:56\",\"video\":\"\",\"vorDoi\":\"\",\"vorDoiUrl\":\"\",\"workflowStages\":[]},\"version\":\"v1\",\"identity\":\"rs-8297190\",\"journalConfig\":\"researchsquare\"},\"__N_SSP\":true},\"page\":\"/article/[identity]/[[...version]]\",\"query\":{\"redirect\":\"/article/rs-8297190\",\"identity\":\"rs-8297190\",\"version\":[\"v1\"]},\"buildId\":\"XKTyCvWXoU3ODBz1xrDgd\",\"isFallback\":false,\"isExperimentalCompile\":false,\"dynamicIds\":[84888],\"gssp\":true,\"scriptLoader\":[]}","source_license":"CC-BY-4.0","license_restricted":false}