Intraductal proliferative lesions of the breast: morphology, associated risk and molecular biology.

The main objectives of this review are (1) to review the histological criteria and terminology for usual ductal hyperplasia, atypical ductal hyperplasia, flat epithelial atypia and ductal carcinoma in situ; (2) to provide an overview of the risk of breast cancer associated with these various lesions; (3) to discuss established and emerging data on the molecular biology and pathogenesis of these lesions and (4) to discuss management when detected in diagnostic needle core and surgical diagnostic specimens.