Observations on the pathologic diagnosis of selected unusual lesions in needle core biopsies of breast

Pathologic diagnoses rendered on needle core biopsies of mammary lesions are primary determinants of further intervention. Such biopsies are being performed for an ever-widening range of diseases in an attempt to reliably and efficiently render a diagnosis. This review is intended to provide practical guidance to pathologists in dealing with selected unusual lesions encountered in these biopsies. Herein we offer advice on avoiding common diagnostic errors and on considering the relevant differential diagnosis of mucocele-like lesions, spindle-cell metaplastic carcinoma, adenomyoepithelioma, pseudoangiomatous stromal hyperplasia (PASH), collagenous spherulosis, myofibroblastoma, vascular lesions, and lymphoid infiltrates in the breast.