Adenoid cystic carcinoma (ACC) in the male breast is vary rare, and 9 cases have been reported in the literature. We report on a case of ACC in the male breast from the point of the cytological findings. A 58-year-old male noticed a lump measuring 40 mm in the left breast. Cytologically, the myoepithelial and epithelial cells had proliferated and formed clusters with various sizes. In the large clusters, glandular structures and ball-like structures with mucous materials were seen. Histologically, tumor cells had proliferated in the cribriform structures composed of proliferating glands and psuedoglandular elements. ACC was diagnosed based on the immunostaining results.
