Pure pleomorphic rhabdomyosarcomas of the uterus.

Pure rhabdomyosarcoma arising in the uterus is a rare tumor currently classified by the World Health Organization (WHO) as a uterine sarcoma. The records of eight women with uterine rhabdomyosarcomas were retrieved from the files of the Armed Forces Institute of Pathology (AFIP). The eight women presented with vaginal bleeding, abdominal enlargement, or acute abdomen. The mean age of the patients was 64.6 years (range 35-87). Macroscopically, 4 tumors were polypoid endometrial masses, 2 were intramyometrial, 1 was located in the cervix, and 1 was a 15-cm mass involving the endometrium and myometrium with direct extension into the small intestine. Microscopically, the tumors consisted of a variable proportion of large rhabdomyoblasts admixed with smaller round, polygonal, and spindle-shaped cells. No epithelial elements were identified on light microscopy. Tissue from the extrauterine and metastatic lesions was available for review in four cases and also showed pure rhabdomyosarcoma. Immunohistochemical assessment of seven tumors supported the sarcomatous nature of the neoplastic cells. Six patients died of disease within 15 months of initial diagnosis and 1 patient died of a pulmonary embolus. The patient whose 15-cm tumor had extended into the small intestine survived 6 years; she died of a presumed pancreatic carcinoma. Presenting mainly in elderly women, uterine pleomorphic rhabdomyosarcomas are rare, highly malignant tumors with frequent extrauterine spread at presentation. Patients rarely survive beyond 15 months.