[Bilateral breast metastases from prostatic carcinoma: a case report]

We report a case of bilateral breast metastases from prostatic carcinoma. A 49-year-old man with stage D2 prostate cancer, who had been treated by chemoendocrine therapy and radiotherapy for 2 years, complained of bilateral enlarged breasts. Oral administration of diethylstilbestrol diphosphate was started 2 months before the onset of this symptom. A firm mass that was not tender was palpable beneath the skin without fixation on each side. A needle biopsy of the masses showed poorly differentiated adenocarcinoma with positive immunohistopathological staining for prostate-specific antigen. The masses were diagnosed as metastatic adenocarcinoma of prostate gland origin. The patient died 3 months after the diagnosis of breast metastases. Autopsy revealed diffuse lymphogenous metastatic disease. Metastatic prostatic carcinoma to the breast is uncommon. Breast metastases in this patient might be associated with diffuse lymphogenous metastases as well as increased local blood and lymphatic supply caused by extrinsic estrogens.