LAUSR

Purpose The malignant upgrade rate of flat epithelial atypia (FEA) diagnosed on core needle biopsy varies between 0 and 30%. Excision versus observation with radiological follow-up for these lesions remains controversial. We hypothesize that the local rate of FEA is low and that close radiological surveillance is a reasonable treatment option for patients diagnosed with pure FEA on breast needle core needle biopsy. Methods This study was a retrospective review of a prospectively collated provincial pathology database. Patients diagnosed with FEA alone on needle core biopsy between 2006 and 2016 were included in our analysis. Patients who had FEA present together with either in situ or invasive carcinoma within the same biopsy cores were excluded. Along with patient demographics, the size of the lesion on preoperative imaging, the method of extraction, and the presence of co-existing benign and malignant pathology on final excision biopsy were analyzed. An independent pathological review was performed to confirm our results and help reduce inter-observer bias. Results The local rate of malignant upgrade when pure FEA is diagnosed on a breast needle core biopsy is 12%. Age at time of diagnosis, size of original lesion on mammogram, presence of atypical ductal hyperplasia (ADH) or atypical lobular hyperplasia on core needle biopsy, the use of vacuum-assisted biopsy (VAB), or concordant imaging did not significantly correlate with malignant upgrade risk. None of the patients who were managed with radiological follow-up had malignant upgrade during follow-up. Patients undergoing radiological follow-up alone were more likely to have a VAB, concordant imaging, and no concurrent ADH. Conclusion Our local malignant upgrade rate is consistent with published literature. We suggest radiological follow-up is a safe alternative in patients with pure flat epithelial atypia and concordant imaging, particularly those patients with small lesions in which microcalcifications can be removed completely with vacuum-assisted biopsy.