Intra-abdominal embryonal rhabdomyosarcoma in an adult.

Rhabdomyosarcoma is an uncommon neoplasm in the adult population. Sporadic cases of primary rhabdomyosarcoma arising in the abdomen have been reported, but these cases are limited almost exclusively to the pediatric population. We report a well-documented case of primary intra-abdominal rhabdomyosarcoma in a 57-year-old woman. The patient presented with a pelvic mass and an elevated serum CA 125 and was referred to gynecologic oncologists at our institution for a presumed primary gynecologic malignancy. Intraoperatively, amorphous gelatinous tumor comprised a large portion of the peritoneal cavity. Surgical exploration of the abdomen failed to implicate any specific organ as the site of origin of the tumor. The overall histologic pattern of the resected tumor was most consistent with embryonal type rhabdomyosarcoma. To our knowledge this is the first well-documented case report of non-hepatobiliary, adult, intra-abdominal embryonal rhabdomyosarcoma in the English language literature. The presentation of a rare adult sarcoma mimicking a gynecologic malignancy was an unusual feature that complicated the diagnosis in this case.