Prostatic origin of tumors. An immunohistochemical study.

An immunoperoxidase technic was used to localize prostatic acid phosphatase in a variety of primary and metastatic neoplasms. The aim was to explore the histogenesis of tumors affecting the prostate gland and to demonstrate the prostatic origin of metastases in various sites. A highly specific antiserum to prostatic acid phosphatase was raised in rabbits, and the peroxidase-antiperoxidase procedure was carried out on formalin-fixed paraffin-embedded routine pathology material. All specimens from the 37 cases of known primary and metastatic prostatic carcinomas stained positively for prostatic acid phosphatase, regardless of their histologic differentiation. None of the specimens from the 44 cases of proven nonprostatic primary and metastatic tumors stained positively for prostatic specific acid phosphatase. The data suggest that demonstration of prostatic acid phosphatase by the immunoperoxidase technic is a practical, sensitive, and specific test for the prostatic origin of an otherwise unclassifiable primary or metastatic neoplasm.