Columnar cell lesions of the breast.

Columnar cell lesions of the breast comprise a group of conditions characterized by dilation of terminal duct lobular units lined by columnar epithelial cells, ranging from one or two layers of benign epithelium to stratified epithelium with atypia. Although these lesions have been recognized by pathologists for many years, they have recently assumed a new significance due to their increased detection as mammographic calcification, the potential for overdiagnosis as ductal carcinoma in situ (DCIS) and their possible relationship to invasive carcinoma. This short overview aims to outline the pathological features and likely clinical significance of these lesions, with emphasis on diagnostic criteria, terminology and classification, and management strategies.