Smooth-muscle tumors of the vulva. A clinicopathological study of 25 cases and review of the literature.

The clinical and pathological features of 25 smooth-muscle tumors of the vulva were analyzed. The patients ranged in age from 17 to 67 (mean, 37.6) years; two were pregnant. Twenty-three tumors were 1.5 to 16 (mean, 5.2) cm in greatest dimension; the size of two tumors was unknown. Microscopic examination showed that 16 tumors were circumscribed, six had focally infiltrative margins, and the margins could not be evaluated in three tumors. Fourteen tumors were composed mainly of spindle cells; two of these tumors had prominent myxoid stroma. Seven tumors were predominantly epithelioid and had a prominent hyalinized or myxoid stroma; often the cells had a plexiform pattern. Four tumors contained an approximately equal number of epithelioid and spindle cells. Ten tumors had mild, nine moderate, and six severe cytologic atypia. Mitotic figures ranged from 0 to 10 (average, 1.8) per 10 high-power fields (hpf). Immunohistochemically, all the tumors stained for one or more muscle markers. Thirteen of 17 tumors were positive for estrogen receptors, and 16 of 18 were positive for progesterone receptors. Follow-up information ranging from 1 month to 19 years (average, 5 years) was available in 19 cases. Four tumors recurred locally, and one patient with recurrent tumor died of metastases 7 months after the initial operation. We propose an expanded criteria to distinguish between leiomyomas and leiomyosarcomas of the vulva. Tumors that manifest three or all of the four following features should be considered sarcomas: > or = 5 cm in greatest dimension, infiltrative margins, > or = 5 mitotic figures per 10 hpf, and moderate to severe cytologic atypia. Those that have only one of these characteristics should be diagnosed as leiomyoma, and those that exhibit only two of these features should be considered benign but atypical leiomyomas. The sarcomas should be excised with widely negative margins; the leiomyomas and the atypical leiomyomas should be excised conservatively, with long-term, careful follow-up.