Carcinoma of prostate metastatic to breast.

Clinically diagnosed breast metastasis from prostatic carcinoma is rare. Primary breast carcinoma in patients with prostatic primary is also uncommon. Four patients who presented with breast malignancies in the course of their prostatic carcinoma are described. All but one of them had diffuse metastatic disease. Three of them were on estrogens at the time breast malignancy was diagnosed. Difficulties always arise in differentiating primary lesions from metastasis clinically and histopathologically. The development of histochemical methods for acid phosphatase, and the newest indirect immunofluorescent antibody technique, used in one of our patients, helped in making the differentiation between primary lesion and metastatic disease. Diagnosis of prostatic carcinoma metastatic to breast carries a poor prognosis, and may be an indication for aggressive therapy.