Phyllodes tumor of the prostate: recurrent obstructive symptom and stromal proliferative activity.

We report the case of a 59-year-old man with a metachronous development of phyllodes tumor and adenocarcinoma of the prostate. He complained of urinary obstruction and transurethral resections of the prostate (TUR-P) had been performed six times in 10 years. Microscopic examination showed cystically dilated glands consisting of bizarre cells with pleomorphic, hyperchromatic nuclei in the stroma at the sixth TUR-P. Radical prostatectomy was performed against recurrences and adenocarcinoma was incidentally detected. Apparent up-regulation of proliferative nuclear antigens (PCNA), but not p53, was observed in the prostatectomy specimen by Western blotting. Active proliferation of stromal cells is considered to have caused the recurrent obstructive symptom.