Sclerosing adenosis cancerized by intraductal carcinoma.

Sclerosing adenosis is a common proliferative lesion of the mammary lobule which is not associated with an increased risk of developing breast cancer. An unusual case of florid sclerosing adenosis showing extensive cancerization by intraductal carcinoma is reported. The neoplastic nature of the sclerosing lesion can be recognized by the unusual distension of the tubules by cells and the subtle cytological changes, and further confirmed by finding foci of classical intraductal carcinoma.