Can Excision be Avoided for Atypical Ductal Hyperplasia of the Breast Diagnosed on Core Biopsy?

Background: Atypical ductal hyperplasia (ADH) diagnosed on core biopsy (CB) is associated with an upgrade risk to ductal carcinoma in situ (DCIS) or invasive carcinoma on surgical excision (SE). Although single institutional studies have shown observation and surveillance can be considered in a select subgroup, most patients undergo surgery. We aim to identify features least associated with upgrade on SE, thereby identifying patients who may potentially be spared surgery. Methods: We conducted a cross-sectional study at University of Miami analyzing imaging, clinical, and pathologic data of ADH diagnosed on CB. Histopathologic characteristics of ADH on CB and SE were recorded and analyzed. Results: Seventy-one CB from 70 patients were included. CB removed >50% of the imaging target in 69% of cases and ≤50% in 31% of cases, showing complete ductule involvement in 31% and incomplete involvement in 69%. ADH was focal (≤1 focus) in 58% and non-focal (>1 focus) in 42%. On SE, 5 cases upgraded to DCIS. Upgrade was more common when CB removed ≤50% compared to >50% (18% vs. 2%). Complete ADH had a significantly higher upgrade rate than incomplete ADH, with no difference between focal and non-focal. Forty-eight percent had low-risk ADH features, defined as incomplete ADH with >50% target removal. Conclusion: Upgrade is limited to DCIS and related to sampling adequacy and extent of ADH. Careful histologic-radiologic correlation can identify a subgroup of ADH with low-risk features, representing possible candidates for observation and surveillance.