Atypical (Bizarre) Leiomyoma of the Prostate: A Case Report

ABSTRACT

Atypical (bizarre) leiomyoma of the prostate is a very rare neoplasm. Five cases have been reported in English medical literature. A 60-year-old Korean man with a history of prostatism and slightly elevated serum prostate specific antigen was presented. Microscopically, the transurethral resection specimen consisted of a proliferation of hypercellular spindle cells with intersecting bundles. The nuclei of the tumor cells showed marked pleomorphism and hyperchromasia with occasional multinucleated giant cells. Mitoses were seen in areas of up to 2 per 10 high power fields, but there was no evidence of atypical ones. The tumor cells were immunoreactive against anti-smooth muscle actin and desmin antibodies. The proliferative index (10.0%) of the atypical leiomyoma lay between that of a benign smooth muscle and that of a leiomyosarcoma of the prostate. Flow cytometry showed a diploid pattern with an elevated S phase fraction. To the best of our knowledge, this is the first demonstration of atypical leiomyoma of the prostate in a Korean man.