Dermatologic diseases of the breast, areola and nipple.

The range of dermatologic diseases of the breast, nipple, and areola (BNA) skin comprises various inflammatory and neoplastic alterations. BNA skin represents a unique functional unit with considerable emotional, sexual, and cosmetic importance. A specialized approach and adequate sensitivity are required for the diagnosis and treatment of dermatologic diseases in this area. This article reviews the normal anatomy of the breast, common inflammatory, infectious, and benign or malignant proliferative diseases or harmatomas that can present in the breast and nipple skin. Skin diseases in the breast area may be specific to this location or not, and can be classified into proliferative diseases, including malformations and neoplasms, and inflammatory diseases, which encompass both infectious and non-infectious inflammations. Benign proliferations include nipple adenoma, fibrous papules, seborrheic keratoses, gynecomastia, benign subcutaneous tumors, melanocytic and epidermal nevi. Malignant neoformations comprise Paget's disease, invasive breast cancer, inflammatory breast cancer, metastases, melanoma, and non-melanoma skin cancers including Merkel cell carcinoma, but also sarcomas. Inflammatory conditions are atopic, irritant, or allergic nipple eczema, radiation dermatitis, mastopathy and Koebner reactions of other skin diseases due to friction in this area. Infections include bacterial, fungal, and viral entities that might be typical for this area such as borrelial lymphocytoma.