Rare synchronous presentation and development of retroperitoneal dedifferentiated liposarcoma and rectal adenocarcinoma

Abstract

Multiple primary malignancies may occur as synchronous or meta-synchronous tumors in 2–17% of patients. Most multiple primary cancers occur in different locations of the same organ or in other organs such as lung, kidney, prostate, and bone. Occurrence of synchronous colorectal adenocarcinoma with liposarcoma, is exceptionally rare. A 79-year-old male presented with significant weight loss of 2–3 weeks duration following a transurethral resection of prostate. Colonoscopy, performed to determine source of the bleeding, revealed a fungating rectal mass, histologically diagnosed as a moderately differentiated adenocarcinoma. Biopsy of a large retroperitoneal mass, concurrently identified on an abdominal computed tomography (CT) scan, revealed a spindle cell neoplasm, subsequently confirmed as liposarcoma by immunohistochemical and molecular studies. Multiple imaging studies from eight years earlier, to as recent as one year (9 months) prior to the current hospital admission, were all negative for intestinal or peritoneal masses. The synchronous rare occurrence of these two malignancies presenting as large tumor masses within one year of negative abdominal imaging studies warrants consideration of mutual tumor promoting factors contributing to their pathogenesis or apparent rapid growth. Keywords: Multiple primary cancers, Synchronous liposarcoma with colorectal cancer, Soft-tissue sarcoma and adenocarcinomas