A case of intracystic papillary carcinoma with a multilocular cyst of the breast in male.

Intracystic papillary carcinoma of the breast in males is a very rare disease but has an excellent prognosis. We report the case of a 68-year-old man who had a right subareolar soft mass. Imaging examinations showed a multilocular cyst with an intracystic component, and benign disease was diagnosed. Fine needle aspiration of the cyst fluid revealed many malignant cells, and modified radical mastectomy was performed under general anesthesia. Histological examination showed intracystic papillary carcinoma with a multilocular cyst. No positive lymph nodes were involved. The diagnosis of intracystic papillary carcinoma of male breast should be made carefully to avoid misdiagnosing benign disease.