Columnar Cell Change and Columnar Cell Hyperplasia of the Breast

Definition

Breast lesions characterized by a variably proliferative, cytologically bland columnar epithelium, lining dilated terminal duct-lobular units, often with luminal secretions and cytoplasmic blebs on the lining cells

Columnar alteration with prominent apical snouts and secretions (CAPSS) without atypia
Columnar alterations of lobules
Columnar metaplasia
Pretubular hyperplasia

Columnar cell change
- Involves dilated terminal duct-lobular units
- Lined by uniform, ovoid-to-elongate, non-atypical columnar cells
  - One or two cell layers thick
  - Chromatin evenly dispersed
  - Inconspicuous nucleoli
Columnar cell hyperplasia
- Involves dilated terminal duct-lobular units
- Lined by columnar cells identical to those seen in columnar cell change
  - Lining greater than two cells thick
  - May form small mounds, tufts and micropapillations
Both frequently exhibit prominent apical snouts
Flat epithelial atypia (similar lesion but with nuclear atypia) is considered separately