Clinical and surgical effectiveness of the multi-disciplinary standardized management model in the treatment of retroperitoneal liposarcoma: Evidence-based clinical practice experience from Fudan Zhongshan.

BACKGROUND: To assess the correlation between clinical outcomes and diagnostic accuracy of evaluations carried out by a preoperative multidisciplinary team versus standard surgical care for patients with retroperitoneal liposarcoma undergoing surgery. METHODS: This comparative study was conducted retrospectively at a specialist assessment center within Zhongshan Hospital, Fudan University, China, between April 2011 and March 2021. Patients were assigned to a multidisciplinary team or nonmultidisciplinary team cohort based on referral to the multidisciplinary team. The primary outcome measured was long-term clinical prognosis, with other outcomes including diagnostic accuracy, 30-day reoperation, duration of stay, perioperative mortality, and medical complications. To mitigate selection bias, we conducted propensity-score matching. Uni- and multivariable Cox proportional hazard models were then used to evaluate the effect of multidisciplinary teams on postoperative survival. The previously specified questionnaire was used to measure the enhancement of awareness and treatment adherence facilitated by multidisciplinary team management. Data analysis was carried out between January 2023 and August 2023. RESULTS: Of the 521 records that were screened, 139 patients were deemed eligible for inclusion and defined as the multidisciplinary team cohort. At the same time, 382 patients without multidisciplinary team management were also included during that period and defined as the nonmultidisciplinary team cohort. The multidisciplinary team cohort exhibited lower numbers of primary retroperitoneal liposarcoma but a higher tumor grade and a greater proportion of R2 resection. After propensity-score matching, the 1-, 3-, and 5-year overall survival rates were 89.5%, 70.5%, and 62.9%, respectively, in the multidisciplinary team cohort, and 77.1%, 49.8%, and 45.1% in the nonmultidisciplinary team cohort. The diagnostic consistency of the multidisciplinary team group was significantly superior to that of the nonmultidisciplinary cohort (92.5% vs 83.6%, P = .042). Although no significant links were shown with duration of stay (P = .232) and 30-day reoperation (P = .447), the multidisciplinary team participation was linked to a substantial decrease in perioperative mortality (P = .036) and postoperative complications (P = .002). Additionally, the multidisciplinary team group indicated stronger illness awareness and postoperative adherence among individuals with retroperitoneal liposarcoma. CONCLUSION: The study's findings indicate that multidisciplinary team management could result in improved clinical outcomes, higher diagnostic accuracy, and reduced duration of postoperative stays, complications, and perioperative mortality. The intervention may also enhance disease awareness and postoperative compliance in retroperitoneal liposarcoma patients who undergo surgery. However, evidence quality was deemed low, and prospective studies with robust designs are required. Nonetheless, these results are worth considering.

Myxoid Pleomorphic Liposarcoma.

Myxoid pleomorphic liposarcoma (MPLPS) shows a strong predilection for the mediastinum and can affect a wide age range. Clinically, MPLPS exhibits aggressive behavior and demonstrates a worse overall and progression-free survival than myxoid/round cell liposarcoma (MRLPS) and pleomorphic liposarcoma (PLPS). Histologically, MPLPS is characterized by hybrid morphologic features of MRLPS and PLPS, including myxoid stroma, chicken wire-like vasculature, univacuolated and multivacuolated lipoblasts, and high-grade pleomorphic sarcomatous components. In terms of molecular features, MPLPS is distinct from other lipomatous tumors as it harbors genome-wide loss of heterozygosity.

Atypical Spindle Cell/Pleomorphic Lipomatous Tumor.

Atypical spindle cell/pleomorphic lipomatous tumor (ASCPLT) is a rare soft tissue neoplasm, commonly arising in the subcutis (more common than deep soft tissue) of limbs and limb girdles during mid-adulthood. ASCPLT is histologically a lipogenic neoplasm with ill-defined margins composed of a variable amount of spindle to pleomorphic/multinucleated cells within a fibromyxoid stroma. ASCPLTs lack MDM2 amplification, but a large subset show RB1 deletion and variable expression of CD34. Though initially thought to be the malignant form of spindle cell lipoma, ASCPLTs are benign with local recurrences (∼10-15%) and no well-documented dedifferentiation or metastasis.

Intra-Abdominal and Retroperitoneal Benign Lipomatous Tumors-An Extremely Rare Mimic of Liposarcoma and its Diagnostic Challenge.

Background. Lipomas are common superficial soft tissue tumors of mature adipocytes. In contrast, well-differentiated/dedifferentiated liposarcoma typically presents in the retroperitoneum as large masses. We provide clinicopathologic and follow-up details of 9 retroperitoneal/intra-abdominal benign lipomatous tumors (BLT) and discuss the utility of ancillary fluorescence in situ hybridization (FISH) in distinguishing from their malignant counterparts. Design. Clinicopathologic details and histology of 9 intra-abdominal and retroperitoneal lipomas were studied along with ancillary CD10 immunohistochemistry (IHC) and FISH for MDM2 and CDK4 amplification. Results. There were 6 females and 3 males. Median age at diagnosis was 52 years (range 36-81 years). Seven were identified incidentally and 2 presented with primary complaints. On imaging, 7 were considered suspicious for liposarcoma. Grossly, the tumors ranged from 3.4 to 41.2 cm (median 16.5 cm). Histologically, all cases showed well-differentiated BLT, further classified as lipoma (n = 7; 1 with metaplastic ossification, 2 with prominent vessels, and 4 ordinary lipomas) and lipoma-like hibernoma (n = 2)-the latter 2 showed intramuscular lesions with interspersed brown fat. CD10 IHC showed strong staining in the 2 hibernomas, whereas the staining was weak in the remaining. MDM2 and CDK4 amplification were negative by FISH in all. Follow-up (median 18 months) did not show recurrence on clinical or imaging evaluation. Conclusion. Retroperitoneal/intra-abdominal BLT are extremely rare and are indistinguishable clinically and radiographically from liposarcoma. This necessitates molecular confirmation even when the histology is convincingly benign, for a confident diagnosis. Our cohort shows that conservative excision without removal of abutted organs is sufficient in most cases.

Nodular cystic fat necrosis: a distinctive rare soft-tissue mass.

We report the case of a 34-year-old female who was evaluated for a right lower extremity soft-tissue mass, found to be a large cystic lesion bound by fibrous tissue containing innumerable, freely mobile nodules of fat. Her presentation suggested the diagnosis of nodular cystic fat necrosis (NCFN), a rare entity that likely represents a morphological subset of fat necrosis potentially caused by vascular insufficiency secondary to local trauma. Her lesion was best visualized using MRI, which revealed characteristic imaging features of NCFN including nodular lipid-signal foci that suppress on fat-saturated sequences, intralesional fluid with high signal intensity on T2-weighted imaging, and a contrast-enhancing outer capsule with low signal intensity on T1-weighted imaging. Ultrasound imaging offered the advantage of showing mobile hyperechogenic foci within the anechoic cystic structure, and the lesion was otherwise visualized on radiography as a nonspecific soft-tissue radiopacity. She was managed with complete surgical excision with pathologic evaluation demonstrating, similar to the radiologic features, innumerable free-floating, 1-5 mm, smooth, nearly uniform spherical nodules of mature fat with widespread necrosis contained within a thick fibrous pseudocapsule. Follow-up imaging revealed no evidence of remaining or recurrent disease on postoperative follow-up MRI. The differential diagnosis includes lipoma with fat necrosis, lipoma variant, atypical lipomatous tumor, and a Morel-Lavallée lesion. There is overlap in the imaging features between fat necrosis and both benign and malignant adipocytic tumors, occasionally making this distinction based solely on imaging findings challenging. To our knowledge, this is the largest example of NCFN ever reported.

Orbital Liposarcoma Progression From a Well-Differentiated to a Dedifferentiated Type in a Young Patient.

A young male patient presented with unilateral proptosis of the left eye. Laboratory tests and an initial computed tomography scan of the orbit were compatible with euthyroid orbitopathy. He subsequently underwent decompression surgery for unfavorable cosmesis and corneal exposure symptoms with good results, but returned 1 year later for recurrence of proptosis. There was a superomedial fatty density extraconal mass on computed tomography scan. A biopsy done a year later confirmed the diagnosis of well-differentiated liposarcoma from the previously noted mass and a dedifferentiated component in the newly appeared mass in the intraconal space. Orbital exenteration with radial forearm free flap was performed followed by orbital radiotherapy. No disease recurrence or metastasis was seen on follow-ups for 7 years since undergoing treatment.

MDM2 FISH testing criteria in adipose tissue tumors with mature adipocytic morphology - A resection case-based study.

The current criteria for utilizing MDM2 Fluorescence In Situ Hybridization (FISH) in adipose-derived tumors were first introduced in 2015 and have been widely adopted. However, these criteria may fail to identify some atypical lipomatous tumors / well-differentiated liposarcoma (ALT/WDL) with mature adipocytic morphology in clinical practice, possibly due to the fact that the existing criteria are primarily based on biopsy cases. Hence, a criterion based on resection cases is needed. In this study, we included 87 adipose tissue tumors with mature adipocytic morphology which were first resected, as well as 9 consultation cases and 25 recurrent resection cases. The final diagnosis was based on MDM2 amplification status. Among the 87 first-time resection cohort, MDM2 FISH amplification was observed in only 2 (5%) of the 39 superficial cases. Marginal infiltration was significantly different in both the MDM2 FISH negative and positive groups (p < 0.05). Of the 37 intramuscular tumors, 17 (46%) showed MDM2 FISH amplification. The MDM2 amplification positive group had a larger tumor size than MDM2 amplification negative group (p = 0.042). Tumors of larger size (≥11 cm) were highly correlated with MDM2 amplification (p = 0.003), but still, 35.3% of the MDM2 amplification-positive cases had tumor sizes less than 11 cm. Eight (66.7%) out of twelve retroperitoneal/ pelvic cases were MDM2 FISH positive. Among the 25 recurrent cases, twenty (80%) of them had MDM2 FISH amplification. In conclusion, we recommend MDM2 FISH for: 1. superficial cases with marginal infiltration based on adequate margin sampling; 2. all intramuscular tumors, retroperitoneal/pelvic tumors and recurrent tumors, both in resection cases and biopsy cases.

Paratesticular Dedifferentiated Liposarcoma with Rhabdomyoblastic Differentiation: A Case Report and Review of the Literature.

Liposarcomas of the paratesticular tissue is a rare pathological entity. The symptoms are similar to inguinal hernias or hydroceles. We present the case of an 84-year-old man with a rare paratesticular liposarcoma that manifested as painless right hemiscrotal swelling. Testicular tumour markers were negative. Imaging revealed a heterogeneous mass with a fat component. He underwent a radical orchiectomy on the left side to remove the associated mass. This revealed dedifferentiated liposarcoma (DDLS) with rhabdomyoblastic differentiation and MDM2 amplification. The surgical margins were negative, and the patient had a metastatic workup that included magnetic resonance imaging (MRI) of the abdomen and pelvis. Because of the disease's rarity, there is no clear agreement on radiotherapy and chemotherapy roles.

[Large excoriated pleomorphic liposarcoma]. / L'image du mois. Volumineux liposarcome pléomorphe excorié.

Pleomorphic liposarcoma is a rare and aggressive tumour developed from mesenchymal tissue. The clinical presentation is most often a subcutaneous mass syndrome. The surgical excision of such lesions has both a therapeutic and diagnostic confirmation value. We here report the case of a 41-year-old woman with a voluminous gluteal lesion that required surgical treatment.

Les liposarcomes pléomorphes sont des tumeurs malignes rares et agressives d'origine mésenchymateuse. Ces lésions se présentent le plus souvent sous la forme d'un syndrome de masse sous-cutanée. L'exérèse de ces lésions a un intérêt à la fois thérapeutique et de confirmation diagnostique. Nous rapportons le cas d'une patiente de 41 ans présentant une volumineuse lésion fessière redevable d'un traitement chirurgical.

Liposarcoma of spermatic cord mimicking an inguinal hernia A case report and review of the literature.

AIM: Liposarcoma of the spermatic cord (LSC) is a tumour often mistaken for common inguinal swelling as hernia and the aim of this work is to present our case with a review of the Literature to define the management of this rare condition. MATERIAL OF STUDY: A systematic review has been realised, considering English language articles published on Pubmed, between 1956 and 2022, using as key words "Liposarcoma of the spermatic cord". RESULTS: 160 studies described 420 cases of LSC and in 40 cases the patient had undergone surgery with an initial diagnosis of inguinal hernia. DISCUSSION: LSC is a very rare entity of genitourinary malignancies, occurring more often in the spermatic cord and diagnosis can be difficult. Our case and Literature data confirm the role of imaging in not conventional inguinal swelling, to avoid diagnostic mistakes and to define preoperatively the correct surgical management. CONCLUSIONS: Imaging is mandatory in case of diagnostic doubt. The recommended treatment is a radical high orchiectomy with clear margins. A long follow-up period is necessary to detect a local recurrence which may occur even several years after the primary therapy. KEY WORDS: Inguinal swelling, Liposarcoma, Spermatic cord.

Biology and Management of Deep-seated Atypical Lipomatous Tumor of the Extremities.

Adipocytic neoplasms are frequently encountered in clinical practice. Atypical lipomatous tumor (ALT) is a locally aggressive but non-metastasizing adipocytic neoplasm that primarily occurs in the proximal extremities of middle-aged to older adults. Histologically, ALT is divided into adipocytic (lipoma-like), sclerosing and inflammatory subtypes. The sclerosing subtype is an unfavorable prognostic factor for local recurrence. ALT is characterized by supernumerary ring and/or giant rod chromosomes. These rings and giant markers invariably contain amplified sequences originating from the long arm of chromosome 12, including the MDM2 proto-oncogene (MDM2) and cyclin-dependent kinase 4 (CDK4) gene. MDM2 and/or CDK4 nuclear immunopositivity is present in most cases. Confidently differentiating deep-seated ALT from deep-seated ordinary lipoma is often difficult on imaging. Moreover, the sclerosing subtype may mimic a higher grade liposarcoma. Detection of MDM2 amplification by fluorescence in situ hybridization would be helpful diagnostically for ALT in more difficult cases. The standard treatment for deep-seated ALT is surgery. Although there is no consensus on the best surgical approach for deep-seated ALT of the extremities, the use of marginal resection is acceptable to preserve musculoskeletal function. This review provides an overview of the current knowledge on the clinical and imaging characteristics, pathogenesis, histopathology, and management of deep-seated ALT of the extremities.

Epithelioid dedifferentiated liposarcoma: A clinicopathological and molecular study of 6 cases.

In this study, we present six cases of epithelioid dedifferentiated liposarcoma to further characterize its clinical and pathological features. The patients are all adult men with age at presentation ranging from 46 to 64 years (median 58.5 years). The patients presented with nonspecific symptoms of retroperitoneal mass, intermittent dull pain or discomfort. None of the patients had any prior history of a primary tumor. Radiological examinations revealed the presence of ill-demarcated heterogenous mass located in the deep soft tissue, including retroperitoneum (4 cases), pelvis and trunk (1 case each). Grossly, they appeared as solid tumors with focal areas of necrosis being presented in 2 cases. Histologically, all tumors were characterized by sheets of epithelioid cells that displayed marked cellular atypia and brisk mitotic activity. Variable portion of atypical lipomatous tumor/well-differentiated liposarcoma was present in 3 cases. By immunohistochemistry, the high-grade epithelioid component in all 6 cases showed strong and diffuse nuclear staining of MDM2, CDK4 and P16, with partial expression of AE1/AE3 in 3 cases. Fluorescence in situ hybridization analysis revealed high-level amplification of MDM2 in all 6 cases, with co-amplification of CDK4 in 3 cases. Follow up information showed that two patients died of the disease within one year despite multidisciplinary treatment. Due to the striking epithelioid appearance, this rare variant of dedifferentiated liposarcoma may be confused with undifferentiated epithelioid sarcoma, poorly differentiated carcinoma, mesothelioma or other malignancies with epithelioid phenotype. The study presented herein further highlights the aggressive clinical behavior of this unique tumor type. For patients with advanced disease, CDK4 inhibitor may provide an optional targeted treatment.

[Clinical value of fluorescence in situ hybridization with MDM2 and DDIT3 probe in diagnosis of liposarcoma].

OBJECTIVE: To investigate the value of using MDM2 amplification probe and DDIT3 dual-color, break-apart rearrangement probe fluorescence in situ hybridization (FISH) technique in the diagnosis of liposarcoma. METHODS: In the study, 62 cases of liposarcoma diagnosed in Peking University First Hospital from January 2015 to December 2019 were analysed for clinicopathological information. Of these 62 cases of liposarcoma, all were analysed for MDM2 amplification and 48 cases were analysed for DDIT3 rearrangement using a FISH technique. Our study aimed to evaluate the status of MDM2 and DDIT3 by FISH in liposarcoma and correlate it with diagnosis of different subtypes of liposarcoma. The subtypes of liposarcoma were classified according to the FISH results, combined with the relevant clinicopathological features. RESULTS: The patients aged 31-89 years (mean: 59 years) with a 1.75:1 male to female ratio. Histologically, there were 20 cases of atypical lipomatous tumour/well-differentiated liposarcoma (ALT/WDLPS), 26 cases of dedifferentiated liposarcoma (DDLPS), 13 myxoid liposarcoma (MLPS) and 3 pleomorphic liposarcoma (PLPS). Tumors with DDLPS (23/26) and WDLPS (8/20) were localized retroperitoneally, while both tumours of MLPS and PLPS were localized extra-retroperitoneally, and the difference of sites among the four subtypes of liposarcoma was statistically significant (P < 0.05). Histologically, varied mucoid matrix could be observed in the four subtypes of liposarcoma, and the difference was statistically significant (P < 0.05). MDM2 gene amplification was demonstrated in all cases of ALT/WDLPS and DDLPS (100%, 20/20 and 26/26 respectively); DDIT3 gene rearrangement was noted only in MLPS (100%, 13/13); most cases of DDLPS (96.2%, 25/26) and ALT/WDLPS (83.3%, 5/6, 6 cases selected for detection) demonstrated the picture of amplification of the DDIT3 telomeric tag. According to the instructions of DDIT3 break-apart rearrangement probe, the 5' telomere probe and 3' centromere probe spanned but did not cover the DDIT3 gene itself, on the contrary, the 5' telomere probe covered the CDK4 gene, while the DDIT3 and CDK4 gene were located adjacent to each other on chromosome, therefore, when the amplification signal appeared on the telomeric tag of the DDIT3 rearrangement probe, it indeed indicated the CDK4 gene amplification rather than the DDIT3 gene rearrangement. Then the 10 cases with DDIT3 telomeric tag amplification were selected for CDK4 and DDIT3 gene amplification probe FISH tests, and all the cases showed CDK4 gene amplification (100%, 10/10) and two of the 10 cases demonstrated co-amplification of CDK4 and DDIT3 (20%, 2/10); DDIT3 polysomy detected by DDIT3 gene rearrangement probe was found in 1 case of DDLPS and 2 cases of PLPS (66.7%, 2/3) with morphology of high-grade malignant tumour and poor prognosis. CONCLUSION: Our results indicate that a diagnosis of different subtype liposarcoma could be confirmed based on the application of MDM2 and DDIT3 FISH, combined with clinicopathological findings. It is also noteworthy that atypical signals should be correctly interpreted to guide correct treatment of liposarcomas.

Recurrent metastatic retroperitoneal dedifferentiated liposarcoma: a case report and literature review.

BACKGROUND: Retroperitoneal liposarcoma (RPLPS), a rare tumor, is often treated using surgical procedures as the first choice for treatment. However, there is no consensus on the scope of surgical resection. In addition, the treatment outcomes of conventional radiotherapy and chemotherapy have not been satisfactory, particularly for specific types of LPS, such as dedifferentiated LPS. In this case study, we present a brief review of other cases of RPLPS, highlighting the selection of surgical scope for RPLPS and related adjuvant treatment for advanced RPLPS. CASE PRESENTATION: A case study is reported regarding an extremely rare recurrent and metastatic retroperitoneal dedifferentiated LPS. The primary RPLPS tumor, with a diameter of 20 cm and a weight of 2.5 kg, occupied the whole left abdomen and adhered to the left kidney. A surgical tumor resection combined with a left nephrectomy is performed. During the 6th -month postoperative follow-up examination, we observed the local recurrence of the tumor in the operation area, in addition to multiple metastatic tumors in both lungs. Further, the prescribed 3-month targeted treatment with anlotinib significantly reduced the size of the metastatic pulmonary tumors. However, the recurrent retroperitoneal tumors showed no significant change in size. Eventually, we observed no substantial evidence of tumor progression, with the patient's condition under control. CONCLUSION: The case demonstrated that the postoperative recurrence of widespread RPLPS required R0 resection to cure the disease, considering targeted therapy for advanced RPLPS control.

Primary well differentiated hepatic liposarcoma in a meerkat (Suricata suricatta).

A 9-year-old female meerkat (Suricata suricatta) succumbed to progressive abdominal distension, anorexia, and depression. Necropsy revealed an extensively distended abdomen with ascites and markedly enlarged liver. The liver had multiple yellowish masses and displaced the thoracic cavity and abdominal organs. There was no evidence of metastatic lesions based on the gross and microscopic findings. Histologically, the liver mass was composed of locally invasive well-differentiated neoplastic adipocytes with Oil Red O-positive lipid vacuoles. Immunohistochemistry revealed positive immunoreactivity to vimentin, S-100 and negative to pancytokeratin, desmin, smooth muscle actin (SMA), ionized calcium-binding adapter molecule 1 (IBA-1). Thus, the primary well differentiated hepatic liposarcoma was diagnosed based on gross, histological and immunohistochemistry results.

[Retroperitoneal Dedifferentiated Liposarcoma with No Recurrence after 5 Years of Postoperative Radiation Therapy --A Case Report-].

A 49-year-old woman presented to our hospital with right lower back pain and epigastric pressure. A computed tomographic scan showed a 12×7×20 cm retroperitoneal mass comprising fatty components and contrast areas around the right kidney. Based on the results, a right retroperitoneal liposarcoma was suspected. Thus, right retroperitoneal tumor resection combined with right kidney resection was performed. Instances of tumor adhesion were found in the ascending colon, duodenum, and the iliopsoas muscle, which could be dissected ; therefore, combined resection of the intestinal tract was not performed. The resected tumor was found to be mixed with dedifferentiated and well-differentiated components and was diagnosed as dedifferentiated liposarcoma. Due to the presence of positive margins, the patient received 50 Gy in 25 fractions of radiation therapy to the right side of the retroperitoneum as postoperative adjuvant therapy. During the irradiation period, vomiting and anorexia were observed as adverse events. Five years have passed since the surgery, and no local recurrence or late complications due to radiation have been observed. Although dedifferentiated liposarcoma is a highly malignant histological type with a very high local recurrence rate, no adjuvant therapy has been established. Some reports have suggested that postoperative radiation therapy for retroperitoneal sarcoma is effective in terms of survival and local control. However, there are no reports of prospective clinical trials, and the evidence is expected to widen in the near future.

Rare paratesticular localization of dedifferentiated liposarcoma: Case report and review of the literature.

RATIONALE: Dedifferentiated liposarcoma is defined as a malignant tumor that changes its shape from a well-differentiated liposarcoma to a non-liposarcomatous form. Most paratesticular liposarcomas manifest as an inguinal, painless, slow-growing mass. The standard treatment is extensive surgical excision, radiotherapy being proposed for cases with positive margins, those with recurrence, or in cases of the existence of unfavorable prognostic factors. PATIENT CONCERNS: We present the case of a young patient diagnosed initially with left hydrocele, which after 2 years proved to mask a differentiated liposarcoma of the spermatic cord. The initial clinical manifestations were represented by the increase in volume of the left groin-scrotal region and pain at this level. DIAGNOSIS: Microscopic examination in hematoxylin-eosin staining highlighted the presence of lipoblasts and fibroblasts in association with areas of hemorrhage and tumor necrosis. The performed immunohistochemical tests confirmed the diagnosis of dedifferentiated liposarcoma. To support and confirm the presence of the mouse double minute 2 homolog gene mutation, chromogenic in situ hybridization analysis was performed. INTERVENTIONS: The initial treatment was the surgical one. After 2 weeks, the patient received zolendronic acid for hypercalcemia which was caused by the osseous metastasis. OUTCOMES: The patient died secondary to acute renal failure caused by hypercalcemia despite the treatment received. LESSONS: This case underlines the importance of both the correct management of oncological patients, as well as immunohistochemical and genetic tests in the identification of prognostic factors, with the ultimate goal of administering an appropriate oncological treatment.

Evaluation of Classic and Quantitative Imaging Features in the Differentiation of Benign and Atypical Lipomatous Soft Tissue Tumors Using a Standardized Multiparametric MRI Protocol: A Prospective Single-Centre Study in 45 Patients.

BACKGROUND: Discrimination between benign and atypical lipomatous tumors (ALT) is important due to potential local complications and recurrence of ALT but can be difficult due to the often-similar imaging appearance. Using a standardized MRI protocol, this study aimed to rank established and quantitative MRI features by diagnostic value in the differentiation of benign and atypical lipomatous tumors and to develop a robust scoring system. METHODS: Patients with clinical or sonographic suspicion of a lipomatous tumor were prospectively and consecutively enrolled from 2015 to 2019 after ethic review board approval. Histology was confirmed for all ALT and 85% of the benign cases. Twenty-one demographic and morphologic and twenty-three quantitative features were extracted from a standardized MRI protocol (T1/T2-proton-density-weighting, turbo-inversion recovery magnitude, T2* multi-echo gradient-echo imaging, qDIXON-Vibe fat-quantification, T1 relaxometry, T1 mapping, diffusion-weighted and post-contrast sequences). A ranking of these features was generated through a Bayes network analysis with gain-ratio feature evaluation. RESULTS: Forty-five patients were included in the analysis (mean age, 61.2 ± 14.2 years, 27 women [60.0%]). The highest-ranked ALT predictors were septation thickness (gain ratio merit [GRM] 0.623 ± 0.025, p = 0.0055), intra- and peritumoral STIR signal discrepancy (GRM 0.458 ± 0.046, p < 0.0001), orthogonal diameter (GRM 0.554 ± 0.188, p = 0.0013), contrast enhancement (GRM 0.235 ± 0.015, p = 0.0010) and maximum diameter (GRM 0.221 ± 0.075, p = 0.0009). The quantitative features did not provide a significant discriminatory value. The highest-ranked predictors were used to generate a five-tiered score for the identification of ALTs (correct classification rate 95.7% at a cut-off of three positive items, sensitivity 100.0%, specificity 94.9%, likelihood ratio 19.5). CONCLUSIONS: Several single MRI features have a substantial diagnostic value in the identification of ALT, yet a multiparametric approach by a simple combination algorithm may support radiologists in the identification of lipomatous tumors in need for further histological assessment.