CLINICOPATHOLOGICAL STUDY OF 28 UTERINE LEIOMYOSARCOMAS WITH METASTASIS

Twenty-eight smooth muscle tumors of the uterine corpus that exhibited metastasis were studied to determine gross and microscopic features a ssociated with metastasis and potential for metastasis. Seventeen of 2 8 patients were advanced stage at initial diagnosis, and the other 11 patients developed metastases 3 months to 9 years later. Seventy-nine percent of tumors occurred in women 50 years or older. Size was a feat ure of metastatic capability, as 22 tumors were larger than 5 cm. Of t he six neoplasms smaller than 5 cm, five had increased mitotic activit y and cytologic atypia to qualify them as sarcomas, The remaining one with four mitotic figures (MF) per 10 high-power fields (HPF) and 1+ a typia had infiltrative margins and vascular invasion that probably acc ounted for its aggressive behavior, Sixteen cases were composed predom inantly of spindle cells, 10 were epithelioid, and two were myxoid. Cy tologic atypia was a prerequisite for metastasis as it was present in all. On a scale of 3, 12 were nuclear grade 3, 15 were grade 2, and on e was grade 1. The average mitotic activity was 14 MF/10 HPF, and 86% had >4 MF/10 HPF. Of the five leiomyosarcomas with low mitotic activit y (fewer than 5 MF/10 HPF), three were the spindle cell variety, one w as epithelioid, and one was myxoid. An epithelioid cell type occurred in 39% of tumors and is a feature that identities a neoplasm capable o f metastasis, even with low mitotic activity.