Papillary adenocarcinomas of the prostate. An immunohistochemical study

Five cases of papillary adenocarcinomas of the prostate were studied for prostate-specific acid phosphatase, using the immunoperoxidase method, to determine the origin and histogenesis of these uncommon tumors. All five cases were prostatic-acid-phosphatase positive, whereas four cases showed in situ carcinoma involving large periurethral ducts. Positive immunohistochemical localization of prostate-specific acid phosphatase is useful in identifying papillary carcinoma of true prostatic origin and distinguishing them from prostatic-acid-phosphatase-negative carcinomas which may include tumors arising from periurethral glands or metaplastic urethral mucosa.