UNASSIGNED: Among liposarcomas, well-differentiated liposarcoma and dedifferentiated liposarcoma are the most common. The majority of these tumors are found in deep retroperitoneum or extremities. When found outside the retroperitoneum, these adipose-derived tumors are known as atypical lipomatous tumors (ALT). Superficial ALT are particularly rare; thus, little is known about their clinical presentation, genomic status, and management. Here, we present the case of a 54-year-old man with an intermittently bothersome, slowly growing mass on his left upper back for over 2 years, which was incidentally diagnosed as ALT. This patient\'s ALT, however, showed a profound degree of pleomorphism with MDM2 and control centromere 12 (CEP12) coamplification and negative CD34 and S100 and RB1 expression, unlike most other ALT described in the literature. This case report details the diagnostic workup and histopathological findings for adipose tumors and summarizes the different subtypes, including atypical spindle cell/pleomorphic lipomatous tumor, pleomorphic liposarcoma, and spindle cell/pleomorphic lipoma, with brief discussion on management.

BACKGROUND: This is a multicentre, single-arm, phase II study aimed at further exploring the activity of trabectedin as second-/further-line treatment in retroperitoneal leiomyosarcoma (LMS) and well-differentiated/dedifferentiated liposarcoma (LPS).
METHODS: The primary endpoint was the growth modulation index (GMI) defined as the ratio between PFS under trabectedin (PFS) and during previous chemotherapy treatment: time to progression (TTP-1). Secondary endpoints were objective response rate (ORR) and PFS. As per protocol, patients were considered responders if the GMI was >1.33, non-responders if <0.75 and neither if 0.76-1.32.
RESULTS: Overall 91 patients were assessable for the primary endpoint (32 patients with LMS and 59 patients with LPS): the median number of cycles received was 6.0 (Q1-Q3 3.0-12.0), and the main reason for treatment discontinuation was disease progression in 72% of patients. The median PFS was 6.0 months, while the median TTP1 was 7.5 months (8.1 and 6.4 months for LMS and LPS, respectively). Thirty-three patients [52%, 95% confidence interval (CI) 36% to 58%, P = 0.674, odds of response 1.1] had a GMI >1.33 (LMS 46%, 95% CI 26% to 67%, odds of response 0.85; LPS 56%, 95% CI 40% to 72%, odds of response 1.3). Overall, in LPS we observed 15/47 patients with a GMI <0.5 and 15/47 patients with a GMI >2. Among LMS patients, 9/26 had a GMI <0.5 and 10/26 had a GMI >2. Overall, ORR (complete response + partial response) was 16% (24% for LMS and 12% for LPS).
CONCLUSIONS: While the primary endpoint of the study was not met, we noticed a subgroup of patients with a markedly discrepant TTP with trabectedin in comparison to previous therapy (GMI <0.5 or >2, the latter including some patients with a long TTP with trabectedin). A mismatch between PFS and overall survival was observed, possibly due to the natural history of the two different histologies and the availability of further lines in LMS.

UNASSIGNED: Atypical spindle cell/pleomorphic lipomatous tumor is categorized as a benign lipomatous tumor, but various MRI findings pose accurate diagnostic challenges. In our case, both MRI and PET/CT scans indicated the possibility of atypical lipomatous tumor/well-differentiated liposarcoma or dedifferentiated liposarcoma. Needle biopsy suggested benign to low-grade malignancy; hence, we opted for the wide resection. The final diagnosis of atypical spindle cell/pleomorphic lipomatous tumor was confirmed through histopathology analysis, including immunohistochemistry and fluorescence in situ hybridization. Since achieving an accurate diagnosis solely through imaging can be challenging, histopathology remains essential.

OBJECTIVE: Cure models are a useful alternative to Cox proportional hazards models in oncology studies when there is a subpopulation of patients who will not experience the event of interest. Although software is available to fit cure models, there are limited tools to evaluate, report, and visualize model results. This article introduces the cureit R package, an end-to-end pipeline for building mixture cure models, and demonstrates its use in a data set of patients with primary extremity and truncal liposarcoma.
METHODS: To assess associations between liposarcoma histologic subtypes and disease-specific death (DSD) in patients treated at Memorial Sloan Kettering Cancer Center between July 1982 and September 2017, mixture cure models were fit and evaluated using the cureit package. Liposarcoma histologic subtypes were defined as well-differentiated, dedifferentiated, myxoid, round cell, and pleomorphic.
RESULTS: All other analyzed liposarcoma histologic subtypes were significantly associated with higher DSD in cure models compared with well-differentiated. In multivariable models, myxoid (odds ratio [OR], 6.25 [95% CI, 1.32 to 29.6]) and round cell (OR, 16.2 [95% CI, 2.80 to 93.2]) liposarcoma had higher incidences of DSD compared with well-differentiated patients. By contrast, dedifferentiated liposarcoma was associated with the latency of DSD (hazard ratio, 10.6 [95% CI, 1.48 to 75.9]). Pleomorphic liposarcomas had significantly higher risk in both incidence and the latency of DSD (P < .0001). Brier scores indicated comparable predictive accuracy between cure and Cox models.
CONCLUSIONS: We developed the cureit pipeline to fit and evaluate mixture cure models and demonstrated its clinical utility in the liposarcoma disease setting, shedding insights on the subtype-specific associations with incidence and/or latency.

Retroperitoneal liposarcoma during pregnancy is rare and poses significant diagnostic challenges, even for experienced specialists. We present a case report of a 27-year-old female patient, 15 weeks pregnant, who was admitted to the hospital due to a massive retroperitoneal liposarcoma. The patient underwent surgical resection of the tumor. Postoperative pathology confirmed a diagnosis of well-differentiated liposarcoma. Although liposarcoma during pregnancy is rare and challenging to diagnose, CT or MRI plays a crucial role in its detection. The recurrence rate depends on the pathological stage, histological grade, and ability to resect the tumor.

Lipomatous pseudohypertrophy of the pancreas (LPH) is a rare disease in which the pancreatic parenchyma is replaced with mature adipose tissue. It is an idiopathic condition whose diagnosis is made based on histopathological analyses. Herein, we report the case of a 50-year-old male patient with a lipomatous mass in the head of the pancreas on computed tomography for close examination of a renal tumor. We suspected liposarcoma, and laparotomy was performed. However, histological analyses revealed LPH. Several imaging findings of LPH can enable a noninvasive diagnosis and help its clinical approach.

Liposarcoma (LPS) is a rare soft tissue sarcoma that develops from the differentiation of fat cells, typically occurring in the lower extremities and retroperitoneal space. Depending on its histological morphology and molecular changes, LPS can be divided into various subtypes, each exhibiting distinct biological behaviors. During treatment, especially for LPS arising in the retroperitoneum, the extent and quality of the initial surgery are critically important. Treatment strategies must be tailored to the specific type of LPS. Over the past few decades, the treatment of LPS has undergone numerous advancements, with new therapeutic approaches such as targeted drugs and immunotherapies continually emerging. This paper reviews the biological characteristics, molecular alterations, as well as surgical and pharmacological treatments of various LPS subtypes, with the aim of enhancing clinicians\' understanding and emphasizing the importance of individualized precision therapy. With a deeper understanding of the biological characteristics and molecular alterations of LPS, future treatment trends are likely to focus more on developing personalized treatment plans to better address the various types of LPS.

BACKGROUND: As a common soft tissue sarcoma, liposarcoma (LPS) is a heterogeneous malignant tumor derived from adipose tissue. Due to the high risk of metastasis and recurrence, the prognosis of LPS remains unfavorable. To improve clinical treatment, a robust risk prediction model is essential to evaluate the prognosis of LPS patients.
METHODS: By comprehensive analysis of data derived from GEO datasets, differentially expressed genes (DEGs) were obtained. Univariate and Lasso Cox regressions were subsequently employed to reveal distant recurrence-free survival (DRFS)-associated DEGs and develop a prognostic gene signature, which was assessed by Kaplan-Meier survival and ROC curve. GSEA and immune infiltration analyses were conducted to illuminate molecular mechanisms and immune correlations of this model in LPS progression. Furthermore, a correlation analysis was involved to decipher the therapeutic significance of this model for LPS.
RESULTS: A six-gene signature was developed to predict DRFS of LPS patients and showed higher precision performance in more aggressive LPS subtypes. Then, a nomogram was further established for clinical application based on this risk model. Via GSEA, the high-risk group was significantly enriched in cell cycle-related pathways. In the LPS microenvironment, neutrophils, memory B cells and resting mast cells exhibited significant differences in cell abundance between high-risk and low-risk patients. Moreover, this model was significantly correlated with therapeutic targets.
CONCLUSIONS: A prognostic six-gene signature was developed and significantly associated with cell cycle pathways and therapeutic target genes, which could provide new insights into risk assessment of LPS progression and therapeutic strategies for LPS patients to improve their prognosis.

Tumors originating from soft tissues are uncommon, among these tumors, liposarcomas are the most frequent. These tumors remain asymptomatic for a long time, and only revealing themselves when they reach an important size. In such cases, treatment is difficult, requiring extensive surgery procedures that can excise several adjacent structures, potentially completed by adjuvant radiotherapy. Despite successful treatment, the recurrence rate remains very high. We report the case of a giant liposarcoma requiring a monobloc extensive resection involving the removal of the tumor, left kidney, left adrenal gland, and a portion of the posterior abdominal wall.

BACKGROUND: Retroperitoneal liposarcoma (RLPS) constitutes the majority of retroperitoneal sarcomas. While surgical resection remains the sole curative approach, determining the optimal surgical strategy for RLPS remains elusive. This study addresses the ongoing debate surrounding the optimal surgical strategy for RLPS.
METHODS: We recruited 77 patients with RLPS who underwent aggressive surgical policies. Patients were categorized into three surgical subtypes: suprapancreatic RLPS, pancreatic RLPS, and subpancreatic RLPS. Our standardized surgical strategy involved resecting macroscopically uninvolved adjacent organs according to surgical subtypes. We collected clinical, pathological and prognostic data for analyses.
RESULTS: The median follow-up was 45.5 months. Overall survival (OS) and recurrence-free survival (RFS) were significantly correlated with multifocal RLPS, pathological subtype, recurrent RLPS and histological grade (P for OS = 0.011, 0.004, 0.010, and < 0.001, P for RFS = 0.004, 0.001, < 0.001, and < 0.001, respectively). The 5-Year Estimate OS of well-differentiated liposarcoma (WDLPS), G1 RLPS, de novo RLPS and unifocal RLPS were 100%, 89.4%, 75.3% and 69.1%, respectively. The distant metastasis rate was 1.4%. The morbidity rates (≥ grade III) for suprapancreatic, pancreatic, and subpancreatic RLPS were 26.7%, 15.6%, and 13.3%, respectively. The perioperative mortality rate is 2.6%.
CONCLUSIONS: Standardized aggressive surgical policies demonstrated prognostic benefits for RLPS, particularly for G1 RLPS, WDLPS, unifocal RLPS, and de novo RLPS. This approach effectively balanced considerations of adequate exposure, surgical safety, and thorough removal of all fat tissue. G1 RLPS, WDLPS, unifocal RLPS, and de novo RLPS could be potential indications for aggressive surgical policies.