Flat epithelial atypia with and without atypical ductal hyperplasia: to re-excise or not. Results of a 5-year prospective study.

Flat epithelial atypia (FEA) of the breast have a tendency to calcify and, as such, are becoming increasingly detected by mammography. There is no consensus yet on whether to excise these lesions or not after diagnosis on core needle biopsies (CNB). We reviewed 3,948 cases of breast CNB between June 2004 and June 2009 correlating histomorphologic, radiological, and clinical features. There were 3.7 % (145/3,948) pure FEA and 1.5 % (58/3,948) concomitant FEA and atypical ductal hyperplasia (ADH). In the pure FEA population, 46.2 % (67/145) had microcalcifications on mammography with 65.5 % (95/145) of patients undergoing subsequent excisional biopsies with the following findings: benign 20 % (19/95), ADH 37.9 % (36/95), ductal carcinoma in situ (DCIS) 1.1 % (1/95), and DCIS and invasive ductal carcinoma (IDC) 2.1 % (2/95). In the concomitant FEA and ADH group, 86.2 % (50/58) patients had microcalcifications on radiograph with 74.1 % (43/58) of patients undergoing subsequent excisions with: benign 23.3 % (10/43), DCIS 9.3 % (4/43), DCIS and IDC 4.7 % (2/43), DCIS + lobular carcinoma in situ + invasive lobular carcinoma 2.3 % (1/43), and tubular carcinoma 2.3 % (1/43). The incidence of carcinoma in the FEA + ADH group is 18.6 % (8/43) and 3.2 % (3/95) for the pure FEA group. This difference is statistically significant (p = 0.0016). The relative risk of carcinoma in the ADH + FEA group versus the pure FEA group is 6.4773, with 95 % CI of 1.8432 and 22.76 24. Five-year mean follow-up in the unexcised pure FEA did not show any malignancies. These findings suggest that pure FEA has a very low association with carcinoma, and these patients may benefit from close clinical and mammographic follow-up while the combined pure FEA and ADH cases may be re-excised.