Figure 2From: The diagnosis and management of pre-invasive breast disease: Flat epithelial atypia – classification, pathologic features and clinical significanceFlat epithelial atypia: columnar cell hyperplasia with atypia. The acini in this terminal duct lobular unit are lined by a few layers of columnar epithelial cells that show low-grade cytologic atypia, characterized by relatively round, monotonous nuclei (hematoxylin & eosin, original magnification 20×).Back to article page