Prostatic leiomyoma with atypia: follow-up study of 10 cases.

We studied the clinical and histologic features of 10 cases of prostatic leiomyoma with atypical bizarre nuclei. Immunohistochemical studies were undertaken in 6 cases. Patient follow-up was obtained in all cases. Patients ranged in age from 50 to 82 years (mean, 65 years) and presented with urinary obstructive symptoms in 7 cases, abnormal digital rectal examination in 3 cases. The histologic findings consisted of a solid circumscribed expansile stromal nodule with abundant smooth muscle and variable numbers of atypical bizarre giant cells. The cells of the tumor displayed intense immunoreactivity for desmin, actin, and androgen receptor and weak to moderate reactivity for vimentin. Four local recurrences were seen, with a follow-up for 3 to 16 years (mean, 7.4 years), but no evidence of sarcomatous transformation occurred. Despite worrisome histologic appearance, a benign clinical behavior was seen in all cases.