ABSTRACT
Breast core biopsies are categorised histologically as B1 (normal) through to B5 (malignant). The extent of an atypical intralobular epithelial proliferation is also impossible to assess in core biopsy samples. Lobular neoplasia confers an increased risk of the subsequent development of invasive carcinoma in either breast. Most columnar cell lesions are categorised as columnar cell change or columnar cell hyperplasia and, as B2, are benign. Columnar cell lesions involve the terminal duct lobular units and the acini in Flat Epithelial Atypia are mildly to moderately dilated with rounded, internal aspects and bear secretions with luminal microcalcification and this entity is therefore typically a screen-detected abnormality. Papillary lesions are composed of fibrovascular cores with overlying epithelium and may be seen extending into the duct lumen as finger-like projections.
