Myxoid leiomyosarcoma of the uterus. A report of six cases.

Six myxoid leiomyosarcomas of the uterus are described. Four were located within the myometrium and two lay predominantly within the broad ligament but appeared to have arisen in the outer myometrium. These tumors were characterized grossly by a gelatinous appearance and an apparently circumscribed border. On microscopical examination, however, they were observed to invade adjacent tissue and in two cases the lumens of veins. All the tumors contained copious amounts of myxomatous stroma. Although it was difficult to establish the nature of the neoplastic cells in some areas of these tumors, both light- and electron-microscopical examination showed characteristic features of smooth muscle cells in other areas. The mitotic count varied from 0 to 2/10 high-power fields. Follow-up investigation for periods ranging from 1 to 11 years revealed that four patients died and two are living with disease.