Non-operative breast pathology: columnar cell lesions.

The term "columnar cell lesions" encompasses a spectrum of processes, characterised by variably dilated acini, lined by one to several layers of tightly packed, columnar-shaped epithelial cells. These lesions have received renewed attention in the literature due to their high prevalence in biopsy specimens taken for assessment of mammographically detected microcalcification. In addition, increasing interest has been directed at the sub-set of columnar cell lesions with varying degrees of cytological atypia. Recent observational and molecular genetic studies have provided strong circumstantial evidence to suggest that at least some of these lesions may represent the earliest morphologically identifiable, non-obligate precursor of low grade breast carcinomas. However, the risk of both local recurrence and progression to invasive cancer appears to be exceedingly low. This review provides an update on recent clinicopathological and molecular data on columnar cell lesions and how these have changed our perception of, and the classification system for, these lesions. In addition, guidelines for the management of patients with columnar cell lesions diagnosed in core needle biopsy specimens are provided.