Male breast lesions: gynecomastia and its distinction from carcinoma by aspiration biopsy cytology.

Gynecomastia is a benign proliferative lesion of the male breast. It may present as a diffuse bilateral process or a unilateral, discrete mass, clinically suggestive of carcinoma. We examined the aspiration biopsy cytology of 50 cases of gynecomastia to define the cytologic criteria and to distinguish it from carcinoma. The parameters of cellularity, architecture, single columnar cells, naked nuclei, nuclear and cell size, nuclear and cytoplasmic characteristics, and extraneous cells were accessed. Diagnostic confusion with carcinoma may occur because of cellularity with loose groups and single cells; however, the mixed cell population, composed of cohesive sheets or groups of bland cells, bipolar naked nuclei, and single tall columnar cells, delineates gynecomastia from carcinoma of the male breast.