The histopathology of gynecomastia differs from that of the female breast in that there are no milk-secreting breast lobules and only hyperplasia and cystic dilatation of the milk ducts, accompanied by hyperplasia of the fibrofatty tissue. Gynecomastia of different etiologies has the same histological changes. The early stage is characterized by hyperplasia of the glandular duct system, with lengthening of the ducts, appearance of new ductal bracts and branches, and proliferation of fibroblasts in the stroma. In the late stage (after several years) there is proliferative degeneration of the epithelium, progressive fibrosis and hyaline degeneration, reduction in the number of glandular ducts, and infiltration with mononuclear cells. When the disease progresses to the stage of extensive fibrosis and hyaline degeneration, complete regression of the breast is difficult. Therefore, guys with more than one year of disease who want to change the appearance of their feminized breasts need to consider surgery to solve the problem.