Histomorphologic Features of Biopsy Sites Following Excisional and Core Needle Biopsies of the Breast.

Mammographic studies have documented a number of architectural changes occurring around breast biopsy sites. These changes are well described in the radiological literature, but similar studies do not appear to be present in the pathology literature. We reviewed 100 consecutive mastectomy specimens from women who had undergone prior core needle or excisional biopsies. Multiple sections of the needle tract or excisional biopsy site were reviewed and morphologic findings reported. Hemorrhage, fat necrosis, granulation tissue, necrosis of fibrous tissue, and epithelium along with fibrosis and foreign body type giant cells were common features. Less frequent were areas of synovial metaplasia, atypical spindle cells, atypical duct-like structures, single atypical cells, squamous metaplasia, proliferations of abnormal blood vessels, and hemosiderin deposition. The misinterpretation of atypical spindle cells, single atypical cells, atypical duct-like structures and squamous metaplasia could result in the false-positive diagnosis of residual malignancy. Careful attention to the reactive nature of these changes aids in their distinction from carcinoma.