Majority of flat epithelial atypia diagnosed on biopsy do not require surgical excision

Abstract Background Borderline risk lesions such as flat epithelial atypia (FEA) are increasingly being diagnosed on biopsy. The need for surgery is being debated. In this study, we determined the frequency of histological upgrade following a diagnosis of FEA on biopsy and evaluated potential predictive factors. Methods Retrospective review was done of 194 women who underwent biopsy of indeterminate lesions (total 195 lesions) that were diagnosed as FEA. The review covered a 10-year period. Cases where malignancy was also present together with FEA within the same biopsy cores were excluded. Results Lesions diagnosed as FEA on biopsy were mostly asymptomatic and presented as microcalcifications on mammogram. Flat epithelial atypia was the only abnormality detected in one-third of cases, was associated with a benign or another borderline lesion in another third and was associated with atypical ductal hyperplasia (ADH) in another third. Six patients (3.1%) were later found to have ductal carcinoma-in-situ (DCIS) at surgery. The presence of ADH in the biopsy was the only predictor of histological upgrade to malignancy (P = 0.04, OR 11.24, 95% CI 1.10 – 115.10), and was present in 5 of the 6 patients. Surgery was advised in the last patient because of radiology-pathology discordance. Thirty-six lesions (18.5%) were not excised and no interval progression or malignancy was found on follow up. Conclusion Histological upgrade to malignancy was uncommon in lesions found on biopsy to be FEA. Non-operative management of biopsy-proven FEA can be considered in the absence of ADH and radiology-pathology discordance.