Atypical microglandular adenosis presenting as a breast lump

Microglandular adenosis is a rare, benign, glandular proliferative breast lesion, which also has a more atypical form. It may mimic malignancy clinically, mammographically and pathologically. Histology shows proliferation of glands with an infiltrative pattern and absence of a myoepithelial cell layer, which leads to diagnostic difficulty. We report a case of atypical microglandular adenosis diagnosed in a 78-year-old woman. The typical histological features, differential diagnostic considerations and association with malignancy are discussed.