Giant well-differentiated liposarcoma/Atypical lipomatous tumor of the thigh with 4 years follow-up: a series of two case reports

Giant well-differentiated liposarcoma/Atypical lipomatous tumor of the thigh with 4 years follow-up: a series of two case reports | 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 Giant well-differentiated liposarcoma/Atypical lipomatous tumor of the thigh with 4 years follow-up: a series of two case reports Le Quang Tri, Tran Hoang Duc, Nguyen Thanh Toan, Tran Duc Tai This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9450986/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Well-differentiated liposarcoma/atypical lipomatous tumor (WDLPS/ALT) is the most common type of liposarcoma. This lesion is most frequently observed in patients aged 40–50 years. Although it shows slow growth and a low grade of malignancy, misdiagnosis or inappropriate management may induce local recurrence and metastasis in cases of dedifferentiation. Methods A cross-sectional descriptive study was conducted and the data on ages, gender, duration since tumor detection, associated symptoms and adjacent neurovascular injury were collected. Our diagnostic work-up, surgical treatment technique, outcomes and preoperative complications were also presented. Results Two male patients presented with giant WDLPS/ALT of the thigh (> 10cm). While 33-year-old patient showed mild pain after 4 years noticing the tumor, 64-year-old patient had recognized his asymptomatic tumor 28 years before presenting to our hospital due to rapid growth in recent years. After surgical treatment, the complication of thigh swelling was observed in 64-year-old patient. After 48-month and 59-month follow-up, respectively, the Lower Extremity Functional Scale improved and no local recurrence was recorded. Discussion Patients with giant lipomatous tumors need to be diagnosed and undergo wide resection surgery in order to achieve good outcomes and avoid local recurrence as well as dedifferentiation into higher-grade malignancy. Conclusion Giant lipomatous tumors of the thigh should be detected and treated surgically as soon as possible to achieve good outcomes. Wide resection is the optimal surgical treatment to reduce the risk of local recurrence and metastasis. Liposarcoma well-differentiated case series diagnosis surgery Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 INTRODUCTION Liposarcoma accounts for approximately 20% of all cases of soft tissue tumors ( 1 ). The World Health Organization classified liposarcomas into 4 major types: atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDLPS), dedifferentiated liposarcoma (DDLPS), myxoid liposarcoma, and pleomorphic liposarcoma ( 2 ). Among these types, DDLPS and pleomorphic liposarcomas have high-grade malignancies with a higher risk of metastasis; in contrast, ALT/WDLPS and myxoid liposarcomas are low-grade tumors ( 1 ). The use of the terms ALT and WDLPS remains inconsistent. Some authors use the term ALT for all WDLPS in areas that margin-negative resection cannot be achieved (as recommended by WHO), whereas others still use the term WDLPS for any lesion located deep to the fascia ( 3 ). WDLPS/ALT is the most common subtype of liposarcoma, recorded with approximately 40–45% of all cases. These lesions usually occur in patients aging from 50 to 60 years old, with slow growth and low-grade malignancy ( 4 ). The WDLPS/ALT shows a risk of local recurrence (approximately 30%), but no potential of metastasis unless transforming into dedifferentiation ( 1 , 5 ). The tumors frequently occur in retroperitoneum or lower extremities which are deep and spacious compartments that allow the tumors to grow gradually for prolonged period. Consequently, patients are usually unaware of the masses until they are symptomatic or reach a considerable size. Misdiagnosis or inappropriate management may result in a high rate of local recurrence and possible transformation of WDLPS/ALT into higher-grade sarcomas, thereby detrimentally affecting the patient’s functional outcome and survival. Our study presents two cases of giant liposarcoma in the thigh and their results after 4-year follow-up. MATERIALS AND METHODS We conducted a cross-sectional descriptive study on a case series of three patients (two males and one female) diagnosed with giant soft tissue tumors of the thigh (> 10 cm), who underwent surgical treatment at Military Hospital 175 between 2021 and 2025. All patients provided consent to participate in the study. For each patient, data of age, gender, duration since the patient first noticing the tumor, associated symptoms, and whether the tumor affected adjacent neurovascular structures were collected. Lower limb function was evaluated preoperatively, postoperatively, and during follow-up visits using the Lower Extremity Functional Scale (LEFS) ( 6 ). At each follow-up visit, patients were assessed using the LEFS score, ultrasonography and MRI at predetermined intervals (every 6–12 months). Follow-up visits were scheduled at 1, 3, 6, and 12 months postoperatively, and every 6 months thereafter. The LEFS score was calculated by the patients at each follow-up examination. Diagnostic process The patients were clinically examined and the tumor sizes were measured via imaging modality. Ultrasonography was performed to evaluate the characteristics and consistency of the tumors. Electroneuromyography was used in cases with suspected femoral or sciatic nerve injuries, bone scintigraphy and fine-needle biopsy were also performed preoperatively. In addition, a preoperative multidisciplinary discussion with oncologists was carried out to reach a consensus diagnosis and plan subsequent treatment. Pathologist would perform an intraoperative frozen section biopsy in cases of suspicious malignancy. After operation, the removed tumors specimens underwent histopathological analysis for diagnostic confirmation. Surgical procedure All three giant tumors were located in the anterior thigh and near the neurovascular bundle. Therefore, wide longitudinal incisions were made along the thigh to fully expose the full length of the tumors. Dissection was performed carefully to avoid injuries to the neurovascular structures, as tumor compression could displace the vessels and nerves from their usual anatomical positions. A postoperative surgical drain was routinely placed, and a compressive dressing was applied to avoid postoperative hematoma or seroma formation. The first two patients provided informed consent to participate in the study. An additional female patient underwent surgery, but was lost to follow-up. RESULTS General characteristics Table 1 A specific summary of patients’ personal data r Age Gender Time examination Symptom Numbness Complication Post-op time Pre- LEFS Post- LEFS Tumor recurrence 1 33 male 4 Little pain No - 48 52 77 No 2 64 male 28 No No - 59 46 68 No Two male patients participated in our study, aged 33 and 64 years, respectively. Time examination: Duration from symptoms onset to hospital presentation (years). The 33-year-old patient complaint of thigh enlargement with mild pain, he had noticed an unusual mass in his thigh 4 years prior to presentation at our hospital. The 64-year-old patient underwent surgery after 28 years of tumor presence due to rapid enlargement of the thigh in recent years, without any associated symptoms. Both patients had no prior surgical or medical interventions and their family histories were negative for neoplastic diseases or relevant genetic disorders. Their psychosocial status was stable. All tumors were located in the inferior compartment of the thigh. (Fig. 1 ). Nerve compression: No patients showed evidence of nerve compression. Gait and functional impact: The 64-year-old male patient showed an altered gait, with the left leg moving more slowly than the right. Post-op time: Post-operative time (months). The duration of follow-up was 48 and 59 months, respectively. Preoperative and postoperative LEFS score (Table 1 ). No recurrence was observed in either patient to date. Ultrasonography showed two heterogeneous masses located deep to the fascia with well-defined margins. MRI findings showed homogeneous fat intensity with thin septa and well-defined margins, suggesting benign tumors. There was no evidence of invasion into the surrounding soft tissues on MRI; however, the displacement of superficial femoral neurovascular bundle was observed (Fig. 2 ). All patients underwent preoperative bone scintigraphy, which showed tracer uptake localized to the lesion without involvement of the bone. All patients underwent fine-needle biopsy, which revealed lipoma or indeterminate lipomatous tumors. Electroneuromyography was not performed because there was no clinical suspicion of femoral or sciatic nerve injury. Treatment results After the preoperative multidisciplinary discussion, we reached a consensus diagnosis for both patients: Suspected WDLPS/ALT of the thigh. Two patients underwent wide excision with preservation of the tumor capsules. The tumor of 33-year-old patient measured 23 × 13 × 8 cm (Figure 3B), and the tumor of 64-year-old measured 28 × 12 × 6 cm (length × width × height, Figure 3C) and the larger tumor weighed 1.7 kg (Figure 3D). Histopathological results of both tumors confirmed the definitive diagnosis of WDLPS/ALT, suggesting a favorable prognosis (Figure 4). Complication: One patient had postoperative thigh swelling. Numbness at the anterior thigh was not observed in either patient. There were no cases of mortality or major vascular complications. 64-year-old patient developed significant postoperative swelling of the thigh, exceeding its preoperative size. Ultrasonographic findings showed significant soft tissues swelling and normal arterial and venous blood flow. Given that this patient was our first surgical case, compressive dressing was not applied to avoid postoperative swelling, hematoma or seroma. The thigh swelling was entirely cured by anti-edema agent before discharge. Follow-up results: The patients recovered well with normal motor and sensory function. There was no suggestion of recurrence on imaging modalities (Figure 5). DISCUSSION Diagnostic challenge: Benign or Malignant? The distinction between a giant benign lipoma and a WDLPS/ALT is often unclear. Clinically, both lesions may be painless. However, liposarcomas are likely to: Adherence to surrounding tissues. Slow growth, with the degree of malignancy depending on histological features. Deep location beneath the fascia. Yin Cheng et al. (2019) (7) and Yohei Asano et al. (2022) (8) proposed two scoring system in their respective studies. Applying the scoring system proposed by Yin Cheng et al. (2019), the tumors of 33-year-old patient had P = 0.382 ≥ 0.214 (cut-off) and the tumors of 64-year-old patient had P = 0.816 ≥ 0.214, favoring WDLPS/ALT. Applying the scoring system proposed by Yohei Asano et al. (2022) (8), both tumors were scored 11 points > 9 (cut-off point), suggesting WDLPS/ALT. The application of MRI This is the optimal imaging modality. Features such as thick septa (>2 mm), non-adipose soft tissue components within the tumor, and large size (≥10 cm) suggest malignancy (3, 9, 10). However, MRI has limitations in distinguishing lipomas, lipoma variants and well-differentiated liposarcomas, which may lead to misdiagnosis if entirely relying on MRI findings (11, 12). In addition, no significant differences were observed between non-contrast and contrast-enhanced MRI findings in the evaluation of ALT/WDLPS (13). Role of pathology and molecular biology Histopathology remains the gold standard for diagnosis. Ali Naimi et al. recommended that core needle biopsy (CNB) should be performed in all lipomatous tumors located deep in tissue, exceeding 7 cm in size and tumor-associated symptoms as standard operating procedures (14). It has been suggested that CNB is routinely indicated for deep fatty lesions with atypical imaging features (such as thick septa or septal hyperintensity), as well as for lesions larger than 10 cm (10). However, this technique is susceptible to sampling errors (15). In addition, well-differentiated liposarcomas have some cytological features that are highly similar to those of typical benign lipoma. The distinguishing feature is the presence of atypical adipocytic cells (atypical lipoblasts). Currently, assessment of MDM2 and CDK4 gene amplification using fluorescence in situ hybridization (FISH) offers a definitive diagnosis of liposarcomas, with nearly-perfect sensitivity and specificity, which may not be detected by conventional light microscopy (16). Surgical strategy No-touch technique and wide excision were required to avoid local recurrence (17). If only performing marginal surgery, Presman B et al. (2020) reported the recurrence rate of 17% in 36 cases with ALT/WDLPS (18), whereas Kito et al. reported recurrence rate of 23% (7/30 cases) (19). Given that important nerves, such as the femoral nerve, are located anteriorly, it is important to identify and localize them before skin incision. We analyzed MRI images for nerve localization. Liposarcoma may infiltrate or encase nerves, but it rarely displaces them. The skin incision should be long enough for full exposure and control of both ends of the tumor. Dissection should be performed following the principle of proceeding from normal tissue toward the lesion: Surgeons should identify and expose the nerve from normal tissue (proximal or distal to the tumor) before approaching the region compressed by the tumor. This approach helps surgeons create a safe anatomical landmark and facilitates mapping of the nerve location. Nerve-sparing dissection technique This is a challenge because the tumor must be totally removed while preserving neurovascular structure. If the tumor encases the nerve but does not infiltrate the nerve fascicles, surgeon performs epineurium dissection to release the nerve from tumor. When the tumor infiltrates the nerve, “Shell-out” technique should be performed: At areas where the tumor is adherent to the femoral nerve, nerve preservation needs to be prioritized, since wide resection may result in nerve injury. We prioritized dissecting the main tumor mass. In smaller areas where the tumor remains adherent to the nerve, meticulous dissection was performed using microsurgical instrument, blunt retractors or scissors, minimizing the risk of nerve injury. Caution: avoid using monopolar electrocautery or excessive traction especially during dissecting large tumors, and try to preserve the vascular supply of the nerve as much as possible. Postoperative follow-up Although WDLPS/ALT rarely metastasizes to distant organs (such as lungs or liver), it has a high rate of local recurrence and potentially transforms into dedifferentiated liposarcoma, offering a poor prognosis. Therefore, patients need to undergo regular postoperative follow-up with MRI during the first year, followed by imaging every 6-month intervals. Ipponi E et al. (2023) reported a recurrence rate of 25% in patients undergoing marginal resection (17). In 2019, Melissa Vos et al. reported a recurrence rate of 19.4% (37/191 cases) (20). Limitations We acknowledge that this study has several limitations, including a small sample size and the need for a longer follow-up period (over 5 years) to ensure optimal outcome assessment. In addition, immunohistochemical staining for MDM2 and CDK4 to confirm the diagnosis of liposarcoma was not available at our institution. CONCLUSION Giant lipomatous tumors of the thigh should be detected and treated surgically as soon as possible to achieve good outcomes. Multidisciplinary consultation with oncology and pathology specialists is essential before, during (if intraoperative biopsy is required), and after surgery. Wide resection is the optimal surgical treatment to reduce the risk of local recurrence and metastasis. Declarations Ethics approval and consent to participate: This study was approved by 175 military hospital. Informed consent was obtained from all individual participants included in the study. Written informed consent for publication was obtained from the patient. A copy of the written consent is available for review by the Editor-in-Chief of this journal. Consent to publish: The participants have consented to the submission of the case report to the journal Data availability: All data generated or analyzed during this study are included in this published article. Competing interests: The authors declare that they have no competing interests. Funding: The authors did not receive support from any organization for the submitted work. Authors' contributions: T.T.D. and T.L.Q. performed the surgery and collected clinical data. T.T.D., T.L.Q. , D.T.H. wrote the primary manuscript. T.N.T. performed the histopathological analysis and prepared the figures. All authors read and approved the final manuscript. Acknowledgements: The authors would like to express their gratitude to the patients for their trust in our research team and for their kind cooperation/consent to participate in this study. Authors' information (optional): Not applicable. References Dei Tos AP. Liposarcoma: new entities and evolving concepts. Ann Diagn Pathol. 2000;4(4):252-66. Jo V, Fletcher C. WHO classification of soft tissue tumours: an update based on the 2013 (4th) edition. Pathology. 2014;46(2):95-104. Al-Ani Z, Fernando M, Wilkinson V, Kotnis N. The management of deep-seated, lowgrade lipomatous lesions. Br J Radiol. 2018;91(1086):20170725. Burusapat C, Wongprakob N, Wanichjaroen N, Pruksapong C, Satayasoontorn K. Atypical Lipomatous Tumor/Well-Differentiated Liposarcoma with Intramuscular Lipoma-Like Component of the Thigh. Case Rep Surg. 2020;2020:8846932. Thway K. Well-differentiated liposarcoma and dedifferentiated liposarcoma: An updated review. Seminars in diagnostic pathology. 2019;36(2):112-21. Binkley JM, Stratford PW, Lott SA, Riddle DL. The Lower Extremity Functional Scale (LEFS): scale development, measurement properties, and clinical application. North American Orthopaedic Rehabilitation Research Network. Phys Ther. 1999;79(4):371-83. Cheng Y, Ko AT, Huang JH, Lee BC, Yang RS, Liang CW, et al. Developing a clinical scoring system to differentiate deep-seated atypical lipomatous tumor from lipoma of soft tissue. Asian J Surg. 2019;42(8):832-8. Asano Y, Miwa S, Yamamoto N, Hayashi K, Takeuchi A, Igarashi K, et al. A scoring system combining clinical, radiological, and histopathological examinations for differential diagnosis between lipoma and atypical lipomatous tumor/well-differentiated liposarcoma. Sci Rep. 2022;12(1):237. Kransdorf MJ, Murphey MD. Imaging of Soft-Tissue Musculoskeletal Masses: Fundamental Concepts. Radiographics. 2016;36(6):1931-48. Le Nail LR, Crenn V, Rosset P, Ropars M. Management of adipose tumors in the limbs. Orthop Traumatol Surg Res. 2022;108(1S):103162. Gaskin CM, Helms CA. Lipomas, lipoma variants, and well-differentiated liposarcomas (atypical lipomas): results of MRI evaluations of 126 consecutive fatty masses. AJR Am J Roentgenol. 2004;182(3):733-9. Lee YM, Chung HW, Shin MJ, Lee SH, Kim SS, Lee JS, et al. Musculoskeletal magnetic resonance imaging suggesting the possibility of liposarcoma: correlation between radiologists' certainty of diagnosis and pathology results. J Comput Assist Tomogr. 2011;35(4):512-6. Nalbant H, Abdelhafez YG, Bateni C, Godinez F, Lee S, Zhang M, et al. MRI of atypical lipomatous tumor: does contrast help? A multicenter study. Skeletal Radiol. 2025;54(12):2681-93. Naimi A, Putora PM, Rothermundt C, Digklia A, Asencio JM, Bonvalot S, et al. Diagnostic work-up of lipomatous tumors: a decision-making analysis among European sarcoma centers. Insights Imaging. 2025;16(1):123. Zhan H, Cao S, Gao T, Zhang B, Yu X, Wang L, et al. Giant atypical lipomatous tumor/well-differentiated liposarcoma affects lower limb activity: A case report. Medicine (Baltimore). 2019;98(42):e17619. Weaver J, Rao P, Goldblum JR, Joyce MJ, Turner SL, Lazar AJ, et al. Can MDM2 analytical tests performed on core needle biopsy be relied upon to diagnose well-differentiated liposarcoma? Mod Pathol. 2010;23(10):1301-6. Ipponi E, Di Lonardo M, Bechini E, Cordoni M, Cosseddu F, Capanna R, et al. Giant atypical lipomatous tumors of the thigh: a case series. Acta Biomed. 2023;94(5):e2023202. Presman B, Jauffred SF, Korno MR, Petersen MM. Low Recurrence Rate and Risk of Distant Metastases following Marginal Surgery of Intramuscular Lipoma and Atypical Lipomatous Tumors of the Extremities and Trunk Wall. Med Princ Pract. 2020;29(3):203-10. Kito M, Yoshimura Y, Isobe K, Aoki K, Momose T, Suzuki S, et al. Clinical outcome of deep-seated atypical lipomatous tumor of the extremities with median-term follow-up study. Eur J Surg Oncol. 2015;41(3):400-6. Vos M, Grunhagen DJ, Kosela-Paterczyk H, Rutkowski P, Sleijfer S, Verhoef C. Natural history of well-differentiated liposarcoma of the extremity compared to patients treated with surgery. Surg Oncol. 2019;29:84-9. Additional Declarations No competing interests reported. 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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-9450986","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":635888963,"identity":"c6dc2d1e-a32a-4437-ac96-14628ae9b3b8","order_by":0,"name":"Le Quang Tri","email":"","orcid":"","institution":"175 Military hospital","correspondingAuthor":false,"prefix":"","firstName":"Le","middleName":"Quang","lastName":"Tri","suffix":""},{"id":635888964,"identity":"d2c485af-83a2-420b-8daf-5175b19c83f2","order_by":1,"name":"Tran Hoang Duc","email":"","orcid":"","institution":"121 Military hospital","correspondingAuthor":false,"prefix":"","firstName":"Tran","middleName":"Hoang","lastName":"Duc","suffix":""},{"id":635888965,"identity":"752ba62b-5b31-4c5f-83d7-5448dd414059","order_by":2,"name":"Nguyen Thanh Toan","email":"","orcid":"","institution":"175 Military hospital","correspondingAuthor":false,"prefix":"","firstName":"Nguyen","middleName":"Thanh","lastName":"Toan","suffix":""},{"id":635888966,"identity":"34ff63a9-e922-4cc6-86ec-870376d46584","order_by":3,"name":"Tran Duc Tai","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2ElEQVRIiWNgGAWjYFCCBCA2sAGRDMxAzNhASAMPQwJQkUFaAgMbaVoYDpOgxZ49gf3Bj4LzeQb3mw9+LmCwkd1wgMfsAV5beB4wNvYY3C42OMaWLD2DIc0YqMXcAK8WCaDDeAxuJ244xmPGzMNwOHHDAbY0CUJaGv8YnANq4f8G1PKfOC3NPAYHQLawAbUAGQeYj+HXcuZh42wZg+TEmcfSjKV5DJKNZx4moIW9PfnAxzd/7BL7Dh9++Jmnwk6273hjG14taBEBCipm/OpHwSgYBaNgFBABAGOxR8UMEX6kAAAAAElFTkSuQmCC","orcid":"","institution":"HUTECH University","correspondingAuthor":true,"prefix":"","firstName":"Tran","middleName":"Duc","lastName":"Tai","suffix":""}],"badges":[],"createdAt":"2026-04-17 15:53:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9450986/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9450986/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108959478,"identity":"14c675d4-c281-42b6-9622-abbb2fb762a1","added_by":"auto","created_at":"2026-05-11 08:30:03","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":545473,"visible":true,"origin":"","legend":"\u003cp\u003eTumors located in the thigh of two patients\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9450986/v1/4bd8b2b9371ec6cc56b4a169.png"},{"id":108959487,"identity":"4eb65ec7-ede7-40cb-9733-3a97800497ad","added_by":"auto","created_at":"2026-05-11 08:30:07","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":358501,"visible":true,"origin":"","legend":"\u003cp\u003eMRI findings of the tumors\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9450986/v1/a7c77fe2843b187fafb6f74d.png"},{"id":108959446,"identity":"66c55dde-d2b2-4e78-a25b-5d95ce9aec77","added_by":"auto","created_at":"2026-05-11 08:29:55","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":659006,"visible":true,"origin":"","legend":"\u003cp\u003eSurgical incision and resected tumor specimens.\u003cbr\u003e\nA: Surgical incision; B and C: Resected tumors; D: The larger tumor’s weight\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-9450986/v1/9eff998fb31d8f5b6b32034a.png"},{"id":108959444,"identity":"25a1d587-4675-4944-943d-bde536dfad8b","added_by":"auto","created_at":"2026-05-11 08:29:55","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":623942,"visible":true,"origin":"","legend":"\u003cp\u003eMacroscopic and microscopic findings (well-differentiated liposarcoma)\u003c/p\u003e\n\u003cp\u003e(A) gross specimen of the 33-year-old patient, (B) gross specimen of the 64-year-old patient, (C) and (D) histopathological features of the 33-year-old patient showing have atypical nuclei in lipoblast (H\u0026amp;E stain)\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-9450986/v1/885fbf4d8f686241b9d6abd8.png"},{"id":108959467,"identity":"4560949d-462a-4051-bebb-924cc58e364e","added_by":"auto","created_at":"2026-05-11 08:30:02","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":416506,"visible":true,"origin":"","legend":"\u003cp\u003eGood recovery and no evidence of recurrence.\u003cbr\u003e\nA, B: Clinical recovery; C: MRI findings; D: Ultrasonography\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-9450986/v1/b98b7af2314c14ba7e8508b5.png"},{"id":109067505,"identity":"83d42124-cf65-4846-a306-d88a2c4d9ea5","added_by":"auto","created_at":"2026-05-12 09:54:55","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3524209,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9450986/v1/07a2665b-7ab6-421a-a7de-39270cb60752.pdf"},{"id":108959489,"identity":"9ce6c553-179f-4f88-baa7-e7d71e007a5b","added_by":"auto","created_at":"2026-05-11 08:30:08","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":86545,"visible":true,"origin":"","legend":"","description":"","filename":"CAREliposarcoma.docx","url":"https://assets-eu.researchsquare.com/files/rs-9450986/v1/78f81b5220193a8784492795.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Giant well-differentiated liposarcoma/Atypical lipomatous tumor of the thigh with 4 years follow-up: a series of two case reports","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eLiposarcoma accounts for approximately 20% of all cases of soft tissue tumors (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). The World Health Organization classified liposarcomas into 4 major types: atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDLPS), dedifferentiated liposarcoma (DDLPS), myxoid liposarcoma, and pleomorphic liposarcoma (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). Among these types, DDLPS and pleomorphic liposarcomas have high-grade malignancies with a higher risk of metastasis; in contrast, ALT/WDLPS and myxoid liposarcomas are low-grade tumors (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe use of the terms ALT and WDLPS remains inconsistent. Some authors use the term ALT for all WDLPS in areas that margin-negative resection cannot be achieved (as recommended by WHO), whereas others still use the term WDLPS for any lesion located deep to the fascia (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). WDLPS/ALT is the most common subtype of liposarcoma, recorded with approximately 40\u0026ndash;45% of all cases. These lesions usually occur in patients aging from 50 to 60 years old, with slow growth and low-grade malignancy (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). The WDLPS/ALT shows a risk of local recurrence (approximately 30%), but no potential of metastasis unless transforming into dedifferentiation (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). The tumors frequently occur in retroperitoneum or lower extremities which are deep and spacious compartments that allow the tumors to grow gradually for prolonged period. Consequently, patients are usually unaware of the masses until they are symptomatic or reach a considerable size.\u003c/p\u003e \u003cp\u003eMisdiagnosis or inappropriate management may result in a high rate of local recurrence and possible transformation of WDLPS/ALT into higher-grade sarcomas, thereby detrimentally affecting the patient\u0026rsquo;s functional outcome and survival.\u003c/p\u003e \u003cp\u003eOur study presents two cases of giant liposarcoma in the thigh and their results after 4-year follow-up.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cp\u003eWe conducted a cross-sectional descriptive study on a case series of three patients (two males and one female) diagnosed with giant soft tissue tumors of the thigh (\u0026gt;\u0026thinsp;10 cm), who underwent surgical treatment at Military Hospital 175 between 2021 and 2025. All patients provided consent to participate in the study.\u003c/p\u003e \u003cp\u003eFor each patient, data of age, gender, duration since the patient first noticing the tumor, associated symptoms, and whether the tumor affected adjacent neurovascular structures were collected.\u003c/p\u003e \u003cp\u003eLower limb function was evaluated preoperatively, postoperatively, and during follow-up visits using the Lower Extremity Functional Scale (LEFS) (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). At each follow-up visit, patients were assessed using the LEFS score, ultrasonography and MRI at predetermined intervals (every 6\u0026ndash;12 months). Follow-up visits were scheduled at 1, 3, 6, and 12 months postoperatively, and every 6 months thereafter. The LEFS score was calculated by the patients at each follow-up examination.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eDiagnostic process\u003c/strong\u003e \u003cp\u003eThe patients were clinically examined and the tumor sizes were measured via imaging modality. Ultrasonography was performed to evaluate the characteristics and consistency of the tumors. Electroneuromyography was used in cases with suspected femoral or sciatic nerve injuries, bone scintigraphy and fine-needle biopsy were also performed preoperatively. In addition, a preoperative multidisciplinary discussion with oncologists was carried out to reach a consensus diagnosis and plan subsequent treatment. Pathologist would perform an intraoperative frozen section biopsy in cases of suspicious malignancy. After operation, the removed tumors specimens underwent histopathological analysis for diagnostic confirmation.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eSurgical procedure\u003c/strong\u003e \u003cp\u003eAll three giant tumors were located in the anterior thigh and near the neurovascular bundle. Therefore, wide longitudinal incisions were made along the thigh to fully expose the full length of the tumors. Dissection was performed carefully to avoid injuries to the neurovascular structures, as tumor compression could displace the vessels and nerves from their usual anatomical positions. A postoperative surgical drain was routinely placed, and a compressive dressing was applied to avoid postoperative hematoma or seroma formation.\u003c/p\u003e \u003c/p\u003e \u003cp\u003eThe first two patients provided informed consent to participate in the study. An additional female patient underwent surgery, but was lost to follow-up.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eGeneral characteristics\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eA specific summary of patients\u0026rsquo; personal data\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"11\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003er\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGender\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTime\u003c/p\u003e \u003cp\u003eexamination\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSymptom\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eNumbness\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eComplication\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003ePost-op time\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003ePre-\u003c/p\u003e \u003cp\u003eLEFS\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003ePost-\u003c/p\u003e \u003cp\u003eLEFS\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003eTumor recurrence\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003emale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eLittle pain\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003emale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTwo male patients participated in our study, aged 33 and 64 years, respectively.\u003c/p\u003e \u003cp\u003eTime examination: Duration from symptoms onset to hospital presentation (years). The 33-year-old patient complaint of thigh enlargement with mild pain, he had noticed an unusual mass in his thigh 4 years prior to presentation at our hospital. The 64-year-old patient underwent surgery after 28 years of tumor presence due to rapid enlargement of the thigh in recent years, without any associated symptoms. Both patients had no prior surgical or medical interventions and their family histories were negative for neoplastic diseases or relevant genetic disorders. Their psychosocial status was stable. All tumors were located in the inferior compartment of the thigh. (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eNerve compression: No patients showed evidence of nerve compression.\u003c/p\u003e \u003cp\u003eGait and functional impact: The 64-year-old male patient showed an altered gait, with the left leg moving more slowly than the right.\u003c/p\u003e \u003cp\u003ePost-op time: Post-operative time (months). The duration of follow-up was 48 and 59 months, respectively.\u003c/p\u003e \u003cp\u003ePreoperative and postoperative LEFS score (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eNo recurrence was observed in either patient to date.\u003c/p\u003e \u003cp\u003eUltrasonography showed two heterogeneous masses located deep to the fascia with well-defined margins. MRI findings showed homogeneous fat intensity with thin septa and well-defined margins, suggesting benign tumors. There was no evidence of invasion into the surrounding soft tissues on MRI; however, the displacement of superficial femoral neurovascular bundle was observed (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAll patients underwent preoperative bone scintigraphy, which showed tracer uptake localized to the lesion without involvement of the bone.\u003c/p\u003e \u003cp\u003eAll patients underwent fine-needle biopsy, which revealed lipoma or indeterminate lipomatous tumors.\u003c/p\u003e \u003cp\u003eElectroneuromyography was not performed because there was no clinical suspicion of femoral or sciatic nerve injury.\u003c/p\u003e \u003cp\u003e\u003cstrong\u003eTreatment results\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAfter the preoperative multidisciplinary discussion, we reached a consensus diagnosis for both patients: Suspected WDLPS/ALT of the thigh. Two patients underwent wide excision with preservation of the tumor capsules. The tumor of 33-year-old patient measured 23 \u0026times; 13 \u0026times; 8 cm (Figure 3B), and the tumor of 64-year-old measured 28 \u0026times; 12 \u0026times; 6 cm (length \u0026times; width \u0026times; height, Figure 3C) and the larger tumor weighed 1.7 kg (Figure 3D). Histopathological results of both tumors confirmed the definitive diagnosis of WDLPS/ALT, suggesting a favorable prognosis (Figure 4).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eComplication:\u0026nbsp;\u003c/strong\u003eOne patient had postoperative thigh swelling. Numbness at the anterior thigh was not observed in either patient. There were no cases of mortality or major vascular complications. 64-year-old patient developed significant postoperative swelling of the thigh, exceeding its preoperative size. Ultrasonographic findings showed significant soft tissues swelling and normal arterial and venous blood flow. Given that this patient was our first surgical case, compressive dressing was not applied to avoid postoperative swelling, hematoma or seroma. The thigh swelling was entirely cured by anti-edema agent before discharge.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFollow-up results:\u0026nbsp;\u003c/strong\u003eThe patients recovered well with normal motor and sensory function. There was no suggestion of recurrence on imaging modalities (Figure 5).\u003c/p\u003e\u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003e\u003cstrong\u003eDiagnostic challenge: Benign or Malignant?\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe distinction between a giant benign lipoma and a WDLPS/ALT is often unclear. Clinically, both lesions may be painless. However, liposarcomas are likely to:\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eAdherence to surrounding tissues.\u003c/li\u003e\n \u003cli\u003eSlow growth, with the degree of malignancy depending on histological features.\u003c/li\u003e\n \u003cli\u003eDeep location beneath the fascia.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eYin Cheng et al. (2019) (7) and Yohei Asano et al. (2022) (8) proposed two scoring system in their respective studies. Applying the scoring system proposed by Yin Cheng et al. (2019), the tumors of 33-year-old patient had P = 0.382 \u0026ge; 0.214 (cut-off) and the tumors of 64-year-old patient had P = 0.816 \u0026ge; 0.214, favoring WDLPS/ALT. Applying the scoring system proposed by Yohei Asano et al. (2022) (8), both tumors were scored 11 points \u0026gt; 9 (cut-off point), suggesting WDLPS/ALT.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eThe application of MRI\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis is the optimal imaging modality. Features such as thick septa (\u0026gt;2 mm), non-adipose soft tissue components within the tumor, and large size (\u0026ge;10 cm) suggest malignancy (3, 9, 10). However, MRI has limitations in distinguishing lipomas, lipoma variants and well-differentiated liposarcomas, which may lead to misdiagnosis if entirely relying on MRI findings (11, 12). \u0026nbsp;In addition, no significant differences were observed between non-contrast and contrast-enhanced MRI findings in the evaluation of ALT/WDLPS (13).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRole of pathology and molecular biology\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eHistopathology remains the gold standard for diagnosis. Ali Naimi et al. recommended that core needle biopsy (CNB) should be performed in all lipomatous tumors located deep in tissue, exceeding 7 cm in size and tumor-associated symptoms as standard operating procedures (14). It has been suggested that CNB is routinely indicated for deep fatty lesions with atypical imaging features (such as thick septa or septal hyperintensity), as well as for lesions larger than 10 cm (10). However, this technique is susceptible to sampling errors (15).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn addition, well-differentiated liposarcomas have some cytological features that are highly similar to those of typical benign lipoma. The distinguishing feature is the presence of atypical adipocytic cells (atypical lipoblasts). Currently, assessment of MDM2 and CDK4 gene amplification using fluorescence in situ hybridization (FISH) offers a definitive diagnosis of liposarcomas, with nearly-perfect sensitivity and specificity, which may not be detected by conventional light microscopy (16).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSurgical strategy\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo-touch technique and wide excision were required to avoid local recurrence (17). If only performing marginal surgery, Presman B et al. (2020) reported the recurrence rate of 17% in 36 cases with ALT/WDLPS (18), whereas Kito et al. reported recurrence rate of 23% (7/30 cases) (19). Given that important nerves, such as the femoral nerve, are located anteriorly, it is important to identify and localize them before skin incision. We analyzed MRI images for nerve localization. Liposarcoma may infiltrate or encase nerves, but it rarely displaces them.\u003c/p\u003e\n\u003cp\u003eThe skin incision should be long enough for full exposure and control of both ends of the tumor. Dissection should be performed following the principle of proceeding from normal tissue toward the lesion: Surgeons should identify and expose the nerve from normal tissue (proximal or distal to the tumor) before approaching the region compressed by the tumor. This approach helps surgeons create a safe anatomical landmark and facilitates mapping of the nerve location.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eNerve-sparing dissection technique\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis is a challenge because the tumor must be totally removed while preserving neurovascular structure. If the tumor encases the nerve but does not infiltrate the nerve fascicles, surgeon performs epineurium dissection to release the nerve from tumor. When the tumor infiltrates the nerve, \u0026ldquo;Shell-out\u0026rdquo; technique should be performed: At areas where the tumor is adherent to the femoral nerve, nerve preservation needs to be prioritized, since wide resection may result in nerve injury. We prioritized dissecting the main tumor mass. In smaller areas where the tumor remains adherent to the nerve, meticulous dissection was performed using microsurgical instrument, blunt retractors or scissors, minimizing the risk of nerve injury. Caution: avoid using monopolar electrocautery or excessive traction especially during dissecting large tumors, and try to preserve the vascular supply of the nerve as much as possible.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePostoperative follow-up\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAlthough WDLPS/ALT rarely metastasizes to distant organs (such as lungs or liver), it has a high rate of local recurrence and potentially transforms into dedifferentiated liposarcoma, offering a poor prognosis. Therefore, patients need to undergo regular postoperative follow-up with MRI during the first year, followed by imaging every 6-month intervals. Ipponi E et al. (2023) reported a recurrence rate of 25% in patients undergoing marginal resection (17). In 2019, Melissa Vos et al. reported a recurrence rate of 19.4% (37/191 cases) (20).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLimitations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe acknowledge that this study has several limitations, including a small sample size and the need for a longer follow-up period (over 5 years) to ensure optimal outcome assessment. In addition, immunohistochemical staining for MDM2 and CDK4 to confirm the diagnosis of liposarcoma was not available at our institution. \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eGiant lipomatous tumors of the thigh should be detected and treated surgically as soon as possible to achieve good outcomes. Multidisciplinary consultation with oncology and pathology specialists is essential before, during (if intraoperative biopsy is required), and after surgery. Wide resection is the optimal surgical treatment to reduce the risk of local recurrence and metastasis.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u003c/strong\u003e This study was approved by 175 military hospital. Informed consent was obtained from all individual participants included in the study. Written informed consent for publication was obtained from the patient. A copy of the written consent is available for review by the Editor-in-Chief of this journal.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to publish:\u003c/strong\u003e The participants have consented to the submission of the case report to the journal\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability:\u003c/strong\u003e All data generated or analyzed during this study are included in this published article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u003c/strong\u003e The authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e The authors did not receive support from any organization for the submitted work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions:\u003c/strong\u003e T.T.D. and T.L.Q. performed the surgery and collected clinical data. T.T.D., T.L.Q. , D.T.H. wrote the primary manuscript. T.N.T. performed the histopathological analysis and prepared the figures. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements:\u0026nbsp;\u003c/strong\u003eThe authors would like to express their gratitude to the patients for their trust in our research team and for their kind cooperation/consent to participate in this study.\u003c/p\u003e\n\u003cp\u003eAuthors\u0026apos; information (optional): Not applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eDei Tos AP. Liposarcoma: new entities and evolving concepts. Ann Diagn Pathol. 2000;4(4):252-66.\u003c/li\u003e\n\u003cli\u003eJo V, Fletcher C. WHO classification of soft tissue tumours: an update based on the 2013 (4th) edition. Pathology. 2014;46(2):95-104.\u003c/li\u003e\n\u003cli\u003eAl-Ani Z, Fernando M, Wilkinson V, Kotnis N. The management of deep-seated, lowgrade lipomatous lesions. Br J Radiol. 2018;91(1086):20170725.\u003c/li\u003e\n\u003cli\u003eBurusapat C, Wongprakob N, Wanichjaroen N, Pruksapong C, Satayasoontorn K. Atypical Lipomatous Tumor/Well-Differentiated Liposarcoma with Intramuscular Lipoma-Like Component of the Thigh. Case Rep Surg. 2020;2020:8846932.\u003c/li\u003e\n\u003cli\u003eThway K. Well-differentiated liposarcoma and dedifferentiated liposarcoma: An updated review. Seminars in diagnostic pathology. 2019;36(2):112-21.\u003c/li\u003e\n\u003cli\u003eBinkley JM, Stratford PW, Lott SA, Riddle DL. The Lower Extremity Functional Scale (LEFS): scale development, measurement properties, and clinical application. North American Orthopaedic Rehabilitation Research Network. Phys Ther. 1999;79(4):371-83.\u003c/li\u003e\n\u003cli\u003eCheng Y, Ko AT, Huang JH, Lee BC, Yang RS, Liang CW, et al. Developing a clinical scoring system to differentiate deep-seated atypical lipomatous tumor from lipoma of soft tissue. Asian J Surg. 2019;42(8):832-8.\u003c/li\u003e\n\u003cli\u003eAsano Y, Miwa S, Yamamoto N, Hayashi K, Takeuchi A, Igarashi K, et al. A scoring system combining clinical, radiological, and histopathological examinations for differential diagnosis between lipoma and atypical lipomatous tumor/well-differentiated liposarcoma. Sci Rep. 2022;12(1):237.\u003c/li\u003e\n\u003cli\u003eKransdorf MJ, Murphey MD. Imaging of Soft-Tissue Musculoskeletal Masses: Fundamental Concepts. Radiographics. 2016;36(6):1931-48.\u003c/li\u003e\n\u003cli\u003eLe Nail LR, Crenn V, Rosset P, Ropars M. Management of adipose tumors in the limbs. Orthop Traumatol Surg Res. 2022;108(1S):103162.\u003c/li\u003e\n\u003cli\u003eGaskin CM, Helms CA. Lipomas, lipoma variants, and well-differentiated liposarcomas (atypical lipomas): results of MRI evaluations of 126 consecutive fatty masses. AJR Am J Roentgenol. 2004;182(3):733-9.\u003c/li\u003e\n\u003cli\u003eLee YM, Chung HW, Shin MJ, Lee SH, Kim SS, Lee JS, et al. Musculoskeletal magnetic resonance imaging suggesting the possibility of liposarcoma: correlation between radiologists\u0026apos; certainty of diagnosis and pathology results. J Comput Assist Tomogr. 2011;35(4):512-6.\u003c/li\u003e\n\u003cli\u003eNalbant H, Abdelhafez YG, Bateni C, Godinez F, Lee S, Zhang M, et al. MRI of atypical lipomatous tumor: does contrast help? A multicenter study. Skeletal Radiol. 2025;54(12):2681-93.\u003c/li\u003e\n\u003cli\u003eNaimi A, Putora PM, Rothermundt C, Digklia A, Asencio JM, Bonvalot S, et al. Diagnostic work-up of lipomatous tumors: a decision-making analysis among European sarcoma centers. Insights Imaging. 2025;16(1):123.\u003c/li\u003e\n\u003cli\u003eZhan H, Cao S, Gao T, Zhang B, Yu X, Wang L, et al. Giant atypical lipomatous tumor/well-differentiated liposarcoma affects lower limb activity: A case report. Medicine (Baltimore). 2019;98(42):e17619.\u003c/li\u003e\n\u003cli\u003eWeaver J, Rao P, Goldblum JR, Joyce MJ, Turner SL, Lazar AJ, et al. Can MDM2 analytical tests performed on core needle biopsy be relied upon to diagnose well-differentiated liposarcoma? Mod Pathol. 2010;23(10):1301-6.\u003c/li\u003e\n\u003cli\u003eIpponi E, Di Lonardo M, Bechini E, Cordoni M, Cosseddu F, Capanna R, et al. Giant atypical lipomatous tumors of the thigh: a case series. Acta Biomed. 2023;94(5):e2023202.\u003c/li\u003e\n\u003cli\u003ePresman B, Jauffred SF, Korno MR, Petersen MM. Low Recurrence Rate and Risk of Distant Metastases following Marginal Surgery of Intramuscular Lipoma and Atypical Lipomatous Tumors of the Extremities and Trunk Wall. Med Princ Pract. 2020;29(3):203-10.\u003c/li\u003e\n\u003cli\u003eKito M, Yoshimura Y, Isobe K, Aoki K, Momose T, Suzuki S, et al. Clinical outcome of deep-seated atypical lipomatous tumor of the extremities with median-term follow-up study. Eur J Surg Oncol. 2015;41(3):400-6.\u003c/li\u003e\n\u003cli\u003eVos M, Grunhagen DJ, Kosela-Paterczyk H, Rutkowski P, Sleijfer S, Verhoef C. Natural history of well-differentiated liposarcoma of the extremity compared to patients treated with surgery. Surg Oncol. 2019;29:84-9.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Liposarcoma, well-differentiated, case series, diagnosis, surgery","lastPublishedDoi":"10.21203/rs.3.rs-9450986/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9450986/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eWell-differentiated liposarcoma/atypical lipomatous tumor (WDLPS/ALT) is the most common type of liposarcoma. This lesion is most frequently observed in patients aged 40\u0026ndash;50 years. Although it shows slow growth and a low grade of malignancy, misdiagnosis or inappropriate management may induce local recurrence and metastasis in cases of dedifferentiation.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA cross-sectional descriptive study was conducted and the data on ages, gender, duration since tumor detection, associated symptoms and adjacent neurovascular injury were collected. Our diagnostic work-up, surgical treatment technique, outcomes and preoperative complications were also presented.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eTwo male patients presented with giant WDLPS/ALT of the thigh (\u0026gt;\u0026thinsp;10cm). While 33-year-old patient showed mild pain after 4 years noticing the tumor, 64-year-old patient had recognized his asymptomatic tumor 28 years before presenting to our hospital due to rapid growth in recent years. After surgical treatment, the complication of thigh swelling was observed in 64-year-old patient. After 48-month and 59-month follow-up, respectively, the Lower Extremity Functional Scale improved and no local recurrence was recorded.\u003c/p\u003e\u003ch2\u003eDiscussion\u003c/h2\u003e \u003cp\u003ePatients with giant lipomatous tumors need to be diagnosed and undergo wide resection surgery in order to achieve good outcomes and avoid local recurrence as well as dedifferentiation into higher-grade malignancy.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eGiant lipomatous tumors of the thigh should be detected and treated surgically as soon as possible to achieve good outcomes. Wide resection is the optimal surgical treatment to reduce the risk of local recurrence and metastasis.\u003c/p\u003e","manuscriptTitle":"Giant well-differentiated liposarcoma/Atypical lipomatous tumor of the thigh with 4 years follow-up: a series of two case reports","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-11 08:26:26","doi":"10.21203/rs.3.rs-9450986/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"02ffa520-586b-4865-b177-7f6878545511","owner":[],"postedDate":"May 11th, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Rejected","date":"2026-05-12T01:59:11+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-09T06:37:40+00:00","index":24,"fulltext":""},{"type":"reviewerAgreed","content":"69720901596236538789668230164808849346","date":"2026-05-09T04:57:44+00:00","index":23,"fulltext":""},{"type":"reviewerAgreed","content":"27464561390687820594383138961876716797","date":"2026-05-07T00:11:58+00:00","index":19,"fulltext":""},{"type":"reviewersInvited","content":"7","date":"2026-04-29T23:47:45+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-29T19:26:19+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-05-12T02:11:38+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-11 08:26:26","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9450986","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9450986","identity":"rs-9450986","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}