Columnar cell lesions and flat epithelial atypia of the breast
Author: Faruk Skenderi, MD, PhDReviewed by: Semir Vranić, MD, PhDLast reviewed:
- WHO Classification of Tumours Editorial Board. Breast Tumours. 5th ed. IARC; 2019.
- Pinder SE, et al. Clin Radiol. 2018;73(8):682-692. https://doi.org/10.1016/j.crad.2018.04.004 (opens in new tab)
- Elfgen C, et al. Third International Consensus Conference on lesions of uncertain malignant potential in the breast (B3 lesions). Virchows Arch. 2023;483(1):5-20. https://doi.org/10.1007/s00428-023-03566-x (opens in new tab)
- Wahab RA, et al. Upgrade rate of pure flat epithelial atypia diagnosed at core needle biopsy: a systematic review and meta-analysis. Radiol Imaging Cancer. 2021;3(1):e200116. https://doi.org/10.1148/rycan.2021200116 (opens in new tab)
A diagnostic quick-review of columnar cell lesions (CCL) of the breast — columnar cell change, columnar cell hyperplasia, and flat epithelial atypia (FEA) — B3 lesion on core biopsy (NHSBSP); WHO 2019 classification and management.
- Columnar cell change (CCC): a single layer of columnar cells lining variably dilated TDLU acini, with apical snouts and intraluminal secretions/microcalcifications.
- Columnar cell hyperplasia (CCH): same architecture as CCC but with stratification (≥2 cell layers) — still without cytologic atypia.
- Flat epithelial atypia (FEA): CCC or CCH with low-grade (monomorphic) cytologic atypia — round, evenly spaced nuclei, loss of polarity, prominent apical snouts.
- FEA lacks the architectural complexity (micropapillae, rigid bridges, cribriform spaces) required for ADH — those features upgrade the lesion to ADH or low-grade DCIS.
- Microcalcifications are common in CCL/FEA and are the usual reason for biopsy; correlate with mammographic findings.
- FEA is a B3 lesion (uncertain malignant potential) in the core-biopsy classification (NHSBSP); WHO 2019 lists FEA among columnar cell lesions. Upgrade rate to in-situ or invasive carcinoma on excision is low (~5–10%) but non-zero.
- Management: discuss FEA at the breast MDT — vacuum-assisted excision or surgical excision is commonly recommended; pure CCC/CCH without atypia does not require excision.
- FEA frequently coexists with lobular neoplasia, ADH, low-grade DCIS, and tubular carcinoma — the so-called 'low-grade breast neoplasia family' (Rosen triad).