Dedifferentiated Liposarcoma Presenting as Primary Diffuse Peritoneal Sarcomatosis: A Case Report and Literature Review.

Authors

Jiongyuan Wang, Quan Jiang, Weiqi Lu, Jinglei Li

Published in

Journal of gastrointestinal cancer. Volume 57. Issue 1. Aug 06, 2026. Epub Aug 06, 2026.

Abstract

Dedifferentiated liposarcoma (DDLPS) typically presents as a solitary retroperitoneal mass; diffuse granular and nodular peritoneal sarcomatosis as the inaugural manifestation is exceptional. We report such a case to highlight a critical diagnostic consideration: distinguishing primary sarcomatous peritoneal dissemination from the more common epithelial peritoneal carcinomatosis.
A 72-year-old Chinese man with no prior abdominal surgery presented with incidentally discovered multifocal intra-abdominal masses. CT demonstrated multiple peritoneal and retroperitoneal masses with encasement of the jejunum and transmural infiltration of the descending colon, and a retroperitoneal plaque abutting the left kidney. CT-guided biopsy confirmed DDLPS via MDM2 and CDK4 amplification on fluorescence in situ hybridization. Multidisciplinary team consensus directed surgical exploration for impending dual-site bowel obstruction. Laparotomy revealed diffuse granular and nodular peritoneal deposits (Peritoneal Cancer Index 28/39); cytoreductive surgery achieved a completeness of cytoreduction score of 2. Histopathology confirmed FNCLCC Grade III DDLPS. Postoperative next-generation sequencing demonstrated high-level co-amplification of CDK4, MDM2, TSPAN31, CCND2, MDM4, and RAC1, with microsatellite stability and tumor mutational burden of 0 mutations/Mb.
DDLPS can present with primary diffuse peritoneal sarcomatosis even with a retroperitoneal component. When diffuse peritoneal implants yield an epithelial-marker-negative spindle cell neoplasm on biopsy, sarcoma must be considered in the differential diagnosis and FISH for MDM2/CDK4 should be performed to avoid misdiagnosis as peritoneal carcinomatosis from gastric, colorectal, or ovarian cancer.

PMID:
42560626
Bibliographic data and abstract were imported from PubMed on 06 Aug 2026.

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