Extragenital primary mixed malignant mesodermal tumor.

Malignant mixed mesodermal tumors (MMMT) are infrequent neoplasms characteristically arising in the endometrium. Extragenital MMMTs are extremely rare, with but 11 cases reported in the literature. Previous extragenital MMMTs have been associated with endometriosis, Wolfian duct remnants, and ovarian cyst adenocarcinoma and have been presumed to arise from coelomic and subcoelomic structures. We report a case of a MMMT arising extragenitally in the cul-de-sac in a 54-year-old White female patient in whom disseminated intraperitoneal serosal papillary serous adenocarcinoma of the peritoneum was present. The histogenesis of this rare neoplasm is discussed along with a brief review of previously reported cases.