Introduction

In association with ever more sensitive radiological techniques, biopsies from lesions of pre invasive and borderline significance are being received increasingly frequently in the laboratory. Such borderline lesions may be difficult to accurately diagnose and classify. Despite good specificity and sensitivity of needle core biopsy (NCB), which is the mainstay of many breast units, there remain lesions that are particularly challenging. This may be because these lesions can (i) mimic carcinoma, (ii) be precursors to invasive disease, (iii) indicate an increased risk of development of carcinoma, or (iv) be associated with carcinoma. The focal nature of sampling inherent with NCB may cause problems with these lesions. Atypical epithelial proliferations, sclerosing lesions and radial scars, papillary, columnar cell and apocrine lesions, and lobular in situ neoplasia are all identified more frequently through radiological techniques than presenting symptomatically. Good communication between surgeon, radiologist, and histopathologist is essential in the breast screening setting, to avoid misdiagnosis, achieve correct classification of these lesions, and ensure optimum patient care.

The widespread introduction of breast cancer screening has led to a marked apparent increase in the incidence of ductal carcinoma in situ (DCIS) as well as invasive disease; this early detection has delivered improvements in outcome. Refinements in radiological techniques, such as digital mammography, have also led to the detection of more and more subtle abnormalities. As a result, there has been an increase in non-operative specimens from impalpable breast lesions, in particular core biopsies, including large volume, vacuum-assisted samples; for example, for microcalcification.