Sclerosing Adenosis (SA) is an increased density of duct-lobular acini, which characteristically are compressed in the central portion of the lesion with dense stroma/fibrosis.  Sometimes these lesions can closely mimic an invasive ducatal carcinoma, immunohistochemistry is necessary to separate lesions.

 

SA is not a neoplastic process, but is associated with a 1.5-2X increased relative risk for breast carcinoma.