Flat epithelial atypia on core needle biopsy does not always mandate excisional biopsy

Flat Epithelia Atypia (FEA) is a proliferative lesion of the breast where cells demonstrate columnar change and cytologic atypia. This lesion has been identified as distinct from the classic atypical hyperplasias (AH). While many patients undergo excisional biopsy, management of FEA identified on core needle biopsy (CNB) is controversial, and the rate of associated ductal carcinoma in situ (DCIS) or invasive cancer is not well defined. The aim of this study was to determine the upstage rate of FEA diagnosed by CNB. We identified patients from a prospectively maintained data base who had FEA diagnosed by CNB from 01/2010 to 07/2015. Patient variables collected included age at presentation, imaging findings, pathologic findings following surgical excision, and subsequent development of breast cancer. Of 132 patients, 62 (n = 62/132, 47.0%) patients had FEA associated with DCIS and invasive ductal carcinoma (IDC) on CNB and were excluded from analysis. Of the remaining 70 patients, median age was 52 (range 31-84) years. Thirty-two (45.7%) patients had FEA plus AH, 4 (5.7%) patients had FEA plus lobular carcinoma in situ (LCIS), and 34 (48.6%) patients had FEA alone or with another non-pathologic finding (pure FEA). Two (6.3%) patients with FEA plus AH had DCIS or IDC on subsequent excisional biopsy. Of the 34 patients with pure FEA who underwent excisional biopsy, only one (2.9%) was found to have IDC. Twenty-two (64.7%) patients with pure FEA who underwent excisional biopsy presented with calcifications on mammography. None of these patients had cancer on excisional biopsy, and 10 (45.5%) patients had AH (3 ADH, 3 ALH, and 4 both ALH and ADH). Twelve (n = 12/34, 35.3%) patients with pure FEA underwent CNB for a mass or asymmetry noted on imaging. Of these 12 patients, 9 (75.0%) had benign findings on excisional biopsy, two (16.7%) patients had AH, and one (8.3%) patient had IDC. Median follow-up was 4.6 years (IQR 3.1-6.5 years). Three (4.3%) patients subsequently developed IDC, two of which were in the contralateral breast. FEA is often found in combination with ADH and ALH as well as carcinoma on CNB. In our study, pure FEA was upstaged to cancer in only 2.9% of patients. Mammographic findings unlikely predict upstaging to malignancy. These findings suggest that excisional biopsy may not be warranted in patients with pure FEA and could be managed with close imaging surveillance.