Influence of Complete Lesion Removal During Vacuum-Assisted Breast Biopsy on the Upgrade Rate of B3 Lesions Presenting as Microcalcifications

<b>Background</b>: B3 lesions of the breast, for which vacuum-assisted biopsy (VABB) represents the standard tissue sampling approach, have different risks of upgrade to malignancy at surgery and/or follow-up. This study aimed to investigate if complete or partial lesion removal during VABB of B3 lesions presenting as microcalcifications influences their subsequent upgrade rate. <b>Methods</b>: For this retrospective single-center study, we retrieved 165 lesions diagnosed as B3 at VABB that presented solely as microcalcifications categorized as Breast Imaging Reporting & Data System (BI-RADS) 4 or 5 at mammography between January 2016 and December 2020. Surgical pathology or at least 3-year follow-up were obtained to determine potential lesion upgrade to malignancy. χ², Fisher's, and Mantel-Haenszel tests were performed to assess if complete lesion removal influenced upgrade rates overall and among different B3 subtypes. <b>Results</b>: Complete lesion removal was achieved in 99/165 cases (60.0%) and did not differ among B3 subtypes (<i>p</i> = 0.092). The overall upgrade rate was 8.5% (95% confidence interval [CI] 5.1-13.7%, 14/165), without statistically significant differences among B3 subtypes (<i>p</i> = 0.562). Conversely, completely removed lesions (4.0%, 95% CI 1.6-9.9%) had a statistically significant lower upgrade rate compared to partially removed lesions (15.2%, 95% CI 8.4-25.7%, <i>p</i> = 0.019). According to stratified analysis according to B3 subtypes, the odds ratio of upgrade among completely and partially removed flat epithelial atypia (0.13, 95% CI 0.00-1.45) was lower (Mantel-Haenszel test <i>p</i> = 0.016) than those of atypical ductal hyperplasia (0.31, 95% CI 0.02-3.17) and of lobular neoplasia (0.73, 95% CI 0.01-60.62). <b>Conclusions</b>: The upgrade rate of B3 lesions is significantly influenced by complete lesion removal, both overall and among different B3 subtypes.