ABSTRACT
The male and female breasts before puberty consist of branching ductal structures arranged in segments and lying within, and supported by, fibrous connective tissue called stroma. The acini and the ducts throughout the breast are lined by cuboidal or low columnar epithelial cells surrounded by an outer layer of contractile myoepithelial cells. Congenital abnormalities of the breast are rare, with the exception of accessory breast parenchyma and accessory nipples. The diagnosis of fibroadenoma confers no predisposition to subsequent breast carcinoma. The circumscribed masses may grow rapidly; rarely unilateral breast enlargement or even skin ulceration may be seen. Infections in the breast are relatively uncommon in developed countries. Acute pyogenic mastitis occurs most often during breast feeding as the result of infection via the ducts, or abrasion of the nipple, from the mouth of the suckling infant. A large number of different morphological types of invasive breast carcinoma are recognized, with different microscopic features, including tumours with mixed appearances.
