Immunohistochemical diagnosis of prostatic cancer with metastasis.

An immunohistochemical method for detecting prostatic acid phosphatase is described for the diagnosis of metastatic prostatic carcinoma. The specific antiserum against prostatic acid phosphatase was prepared from rabbit by injection of acid phosphatase purified from seminal fluid. This method gives a selective staining of the cytoplasm of the glandular epithelial cells of prostatic tissue specimens on paraffin section. Most of the non-prostatic tissues were negative except for occasional weak staining in granulocytes, islet cells of pancreas, parietal cells of stomach, tubular epithelial cells of kidney, and liver cells. Also examined were 50 consecutive cases of metastatic tumor involving the bone marrow and 5 cases of metastatic prostatic carcinoma involving the lymph node or lung. All 20 cases with prostatic primary lesion showed positive staining. All other cases were negative, except 5 of the 14 cases of metastatic breast carcinoma in women showing weakly positive results. The method is fairly specific for identification of metastatic prostatic carcinoma. Occasional positive staining in breast tumor needs further study to establish whether the staining is due to the same isoenzyme or to certain cross immunoreactivity.