Aspiration cytology of lipomatous tumors: a 10-year experience at an orthopedic oncology center.

The cytodiagnoses of preoperative fine-needle aspirate smears from 72 histologically proven lipomatous tumors (52 lipomas and 20 liposarcomas of varying type) collected during the 10-yr period 1972-1981 were correlated to the corresponding histopathologic diagnoses. Three out of 52 lipomas were erroneously diagnosed as low-grade malignant liposarcomas, and one out of 20 liposarcomas was falsely diagnosed as a benign soft-tissue tumor. Of the 20 liposarcomas, 15 were cytologically diagnosed as such, and the majority of the myxoid and the pleomorphic liposarcomas were correctly diagnosed as to type. Important differential diagnostic problems were, on one hand, the separation of lipoma with regressive changes and histiocytic reaction and lipoma with chondroid metaplasia from low-grade malignant liposarcoma and, on the other hand, liposarcoma from intramuscular myxoma, myxofibrosarcoma, and malignant fibrous histiocytoma. The differential diagnosis of liposarcoma as opposed to other soft-tissue sarcomas is discussed, and it is concluded that preoperative fine-needle aspiration of lipomatous tumors is of value in the management of these tumors.