Breast Columnar Cell Lesion

**Semantic type:** Neoplastic Process

**Definition:** A morphologic spectrum of lesions that arise in the terminal ductal lobular units of the breast parenchyma. These lesions are characterized by the presence of columnar epithelial cells that line dilated terminal ductal lobular units. Cytological and architectural atypia may be absent or minimal, or significant enough to raise the possibility of atypical ductal hyperplasia or ductal carcinoma in situ. Columnar cell lesions are frequently found in breast biopsies but their biologic significance is not known.

**Synonyms:** - Columnar Cell Lesion of Breast - Columnar Cell Lesion of the Breast