Epithelioid sarcoma - intra-abdominal

Soft-tissue sarcomas occurring in the abdomen and pelvis are an uncommon yet important group of malignancies.

The most common intra-abdominal sarcomas are GIST, liposarcoma, and leiomyosarcoma which represent the majority of sarcomas occurring in the abdomen and pelvis. GIST is the most common intraperitoneal sarcoma. Liposarcoma is the most common retroperitoneal sarcoma, and leiomyosarcoma is the second most common.

Epithelioid sarcomas represent one of a group called "Sarcomas of uncertain differentiation", this group includes synovial sarcoma, epithelioid sarcoma, alveolar soft part sarcoma, clear cell sarcoma of soft tissue, extraskeletal Ewing sarcoma, desmoplastic small round cell tumor, extrarenal rhabdoid tumor, and malignant perivascular epithelioid cell tumor (“PEComa”). These sarcomas represent less than 1% of all soft-tissue sarcomas.

The sarcomas of uncertain differentiation are grouped together because:

• they have an unknown lineage
• each one of them has distinctive clinical, pathological features, and genetic alteration
• imaging features of these malignancies are nonspecific, and they may occur in the retroperitoneum and abdominal wall and, very rarely, in the peritoneal cavity

This case is courtesy of Dr Fatma El Zahraa Ahmed, and Dr. Lobna