Prostatic adenocarcinoma metastatic to the breasts: report of a case with diagnosis by fine needle aspiration biopsy.

Metastases of tumors of extramammary origin to the breast are extremely uncommon. We report the case of an 81-year-old man with a history of prostatic adenocarcinoma treated with adjuvant estrogen therapy, who presented with bilateral palpable mammary masses. Mammographic study showed irregular solid nodules. Fine needle aspiration (FNA) biopsy was performed. The aspiration smears showed single cells with high nuclear/cytoplasmic ratios, prominent nucleoli, and rare acinar formations. Immunocytochemical studies using antibodies against prostate-specific antigen and prostate-specific acid phosphatase confirmed the diagnosis of metastatic prostatic adenocarcinoma, allowing appropriate treatment.