Demonstration of the prostatic origin of metastases: an immunohistochemical method for formalin-fixed embedded tissue.

An indirect immunohistochemical technique is described for identification of the prostatic origin of metastases in formalin fixed, paraffin or paraplast embedded material. A rabbit antiserum against the prostate specific acid phosphatase isoenzyme was developed. The method is applicable with or without previous decalcification. In 30 cases of prostatic carcinoma there was only one negative result, and in 20 cases of metastases from prostatic carcinoma positive results were obtained in every instance. All carcinomas (primary focus or metastasis) of non prostatic origin (55) stained negatively with the developed antiserum. The application and possible limitations of the method are discussed.