Prostate carcinoma with testicular or penile metastases.  Clinical, pathologic, and immunohistochemical features. 
Despite the proximity, prostate carcinoma seldom metastasizes to the penis or testis.  In the current study, the authors retrospectively examined the clinical history of 12 patients with prostate carcinoma and testicular or penile metastases.  Pathologic review and immunohistochemical staining were performed on tumors from eight of these patients.  Patients with prostate carcinoma and testicular or penile metastasis responded to androgen ablative therapy (median duration, 33 months).  They were predisposed to developing persistent or recurrent urinary symptoms and visceral metastases.  Six of 9 evaluable patients had elevated serum carcinoembryonic antigen levels (> 6 ng/mL), whereas 2 of 10 patients had low or undetectable serum prostate specific antigen levels (< 4 ng/mL).  In seven of the eight patients for whom specimens were available, the tumors were found to contain histologic features that were compatible with a diagnosis of ductal or endometrioid adenocarcinoma of the prostate.  Patients with prostate carcinoma and testicular or penile metastases have unique clinical and pathologic characteristics.  Many of these patients' tumors are compatible with a subtype of prostate carcinoma known as ductal adenocarcinoma.  Further studies need to be performed to elucidate the biologic basis of the various histologic subtypes of prostate carcinoma.