Definition

A common breast biopsy finding in which the cuboidal (square-ish) cells that normally line the lobules (milk glands) of the breast are replaced with one or more layers of column-shaped cells called columnar cells. These columnar cells may look like normal cells or abnormal cells under a microscope. The lobules may also look larger than normal. Breast columnar cell lesions often occur with deposits of calcium in the breast tissue. Breast columnar cell lesions are not cancer but may increase the risk of certain other breast conditions or invasive breast cancer.