Leiomyosarcoma arising in atypical fibromuscular hyperplasia (phyllodes tumor) of the prostate with distant metastasis.

An extremely rare neoplasm of the prostate, commonly known as phyllodes type of atypical prostatic hyperplasia, is described in a 57-year-old man. Over a 2-year period, the atypical smooth muscle component has transformed into leiomyosarcoma, and eventually metastasized to the bones and the lungs. Such an evolution has never been documented for this tumor.