Isolated Flat Epithelial Atypia on Core Biopsy Specimens Is Associated With a Low Risk of Upgrade at Excision.

OBJECTIVES: We present a retrospective review of 111 breast core biopsy specimens with flat epithelial atypia (FEA) and corresponding excision to better understand rates of upgrade following this diagnosis. METHODS: In total, 252 breast core biopsy specimens were identified. Cases were excluded if biopsy slides or excision results were unavailable, for ipsilateral carcinoma or other findings warranting excision, or biopsy performed for indications other than mammographically detected calcifications. Coincident atypical lobular hyperplasia was not excluded. Diagnoses were confirmed by breast pathologists, and mammographic images were reviewed. RESULTS: Ultimately, 111 biopsy specimens with FEA were included. In subsequent excisions, one (1%) of 111 showed invasive carcinoma, 20 (18%) atypical ductal hyperplasia, 20 (18%) lobular neoplasia, 31 (28%) FEA, and 39 (35%) no atypical findings. CONCLUSIONS: FEA on core biopsy specimens is associated with a low rate of upgrade to invasive carcinoma. Close follow-up may be a reasonable alternative to excision for isolated FEA on core needle biopsy specimens.