Bizarre leiomyoma of the scrotum.

Scrotal leiomyomas with atypical bizarre nuclei are rare, which might be misdiagnosed as malignant tumor. We describe a case of scrotal bizarre leiomyoma in a 65-yr-old man. The tumor was a 1 cm-sized, well circumscribed, oval mass arising from the tunica dartos muscle. Histologically, it was formed by whorling bundles of fusiform cells with occasional atypical, pleomorphic nuclei and pseudo-inclusions. Mitosis was not found. Although morphologically atypical, scrotal bizarre leiomyomas take on a biologic behavior not different from that of conventional leiomyoma, they should be distinguished from leiomyosarcoma to avoid unnecessary treatment.