Srour MK, Donovan C, Chung A, et al. - Researchers sought to ascertain the upstage rate of flat epithelia atypia (FEA) diagnosed by core needle biopsy (CNB). From January 2010 to July 2015, 132 patients with FEA were reported; of these, 62 (n = 62/132, 47.0%) patients were excluded due to the association of FEA with ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) on CNB. Among the remaining 70 patients (median age: 52 (range 31-84) years), 32 (45.7%) patients exhibited FEA plus atypical hyperplasias (AH), 4 (5.7%) patients exhibited FEA plus lobular carcinoma in situ (LCIS), and 34 (48.6%) patients had FEA alone or with another non-pathologic finding (pure FEA). DCIS or IDC was identified in two (6.3%) patients with FEA plus AH on subsequent excisional biopsy. Among the 34 patients with pure FEA who underwent excisional biopsy, IDC was identified in only one (2.9%). Among the 22 (64.7%) patients with pure FEA who underwent excisional biopsy, none exhibited cancer on excisional biopsy, and 10 (45.5%) patients exhibited AH (3 ADH, 3 ALH, and 4 both ALH and ADH). For a mass or asymmetry noted on imaging, CNB was performed on 12 (n = 12/34, 35.3%) patients with pure FEA; of these, 9 (75.0%) exhibited benign findings on excisional biopsy, two (16.7%) patients exhibited AH, and one (8.3%) patient exhibited IDC. During the median follow-up of 4.6 years (IQR 3.1-6.5 years), subsequent development of IDC was observed in three (4.3%) patients, two of which were in the contralateral breast. Observations indicated the occurrence of FEA often in combination with ADH and ALH as well as carcinoma on CNB. Only 2.9% of patients exhibited upstaging of pure FEA to cancer in this work. Mammographic findings unlikely predict upstaging to malignancy. Findings thereby indicate that patients with pure FEA may not require excisional biopsy and could be managed with close imaging surveillance.