Histopathologists are encountering intra-lobular epithelial proliferations more frequently in core biopsies taken from lesions identified in mammographic breast screening programmes. In particular, columnar cell lesions are increasingly being seen in core biopsies taken for the histological assessment of mammographically detected microcalcifications. The morphological features of lobular neoplasia are relatively well known, but columnar cell lesions, particularly forms with atypical features, are less widely recognised. The biological and clinical significance of both of these intra-lobular processes is controversial, (1) as indicators of adjacent malignancy when encountered in core biopsy, (2) the relative risk conferred of development of subsequent malignancy, and (3) their precursor behaviour. For this reason, the optimal clinical management of these lesions, particularly when encountered on core biopsy, is unclear. This review provides an update on the histological diagnosis of lobular neoplasia and columnar cell lesions and outlines recent clinico-pathological and molecular findings with discussion on clinical management.