[Prostatic duct adenocarcinoma with pagetoid spread on the glans penis: a case report].

A 75-year-old male visited our division with asymptomatic erythema on the glans penis which he first noticed six months earlier. The patient underwent total cystoprostatectomy under the diagnosis of urothelial carcinoma of the urinary bladder four years earlier. At the time, the prostatectomy specimen incidentally revealed a prostatic acinar adenocarcinoma at the bilateral peripheral zone. A skin biopsy of the erythema revealed intraepithelial Paget's cells, and the patient underwent total penectomy under the diagnosis of extramammary Paget's disease. Histopathological examination revealed continuous intraepithelial Paget's cells from the glans penis to the urethral navicular fossa, and a ductal carcinoma was detected beneath the urethral mucosa to the excisional margin. Because the Paget's cells expressed cytokeratin 20, the tumor was diagnosed as Pagetoid spread rather than Paget's disease. Re-examination of the previous prostatectomy specimen revealed prostatic duct adenocarcinoma with prostatic acinar adenocarcinoma. Therefore, the final diagnosis was prostatic duct adenocarcinoma with Pagetoid spread to the glans penis. Follow up at nine months revealed neither local recurrence, nor distant metastases, although no adjuvant therapy has been given.