Aims Columnar cell lesions are known as a link between normal breast and low grade neoplastic lesions in female, but have not been established in the male breast. This study evaluated the presence of ducts showing columnar cell-like features in the male breast.

Methods Seventy-one consecutive surgical resections from men (6 invasive breast carcinoma of grade 3, 1 atypical ductal hyperplasia and 64 other lesions) were reviewed to identify foci of dilated ducts with columnar epithelial cells, and their morphological features including apical snouts, intraluminal secretions and calcifications were assessed. The expression of CK5/6 and estrogen receptor (ER) was evaluated immunohistochemically. Clinicopathological features including patients’ age, histological diagnosis and gynaecomastoid hyperplasia were documented.

Results Ducts showing columnar cell-like features were identified in 39 cases, morphologically as distended ducts with round or undulating outline. There was an outer layer of myoepithelial cells and an inner layer of columnar luminal cells showing apical snouts, but without intraluminal secretions or calcifications. Immunohistochemically, these columnar epithelial cells were negative for CK5/6 in 38/39 cases and all were ER heterogeneously positive. These changes were associated with older age, but their incidence did not differ whether they were associated with invasive breast carcinoma, atypical ductal hyperplasia and other lesions.

Conclusions In the male breast, there is an entity sharing morphological features and immunohistochemical profile of columnar cell lesions.