Underestimation of atypical ductal hyperplasia at sonographically guided core biopsy of the breast.

OBJECTIVE The purpose of this study was to determine the rate of underestimation of atypical ductal hyperplasia (ADH) at sonographically guided core biopsy of the breast and to identify the factors involved. MATERIALS AND METHODS We retrospectively reviewed 3,563 lesions con secutively evaluated with sonographically guided core biopsy between January 2002 and June 2006. Histologic analysis yielded ADH in 60 of the 3,563 lesions (1.7%). The rate of underestimation of ADH was determined by dividing the number of lesions that proved to be carcinoma at surgical excision by 44, the total number of lesions evaluated with excisional biopsy. Clinical, sonographic, and core biopsy features were analyzed to identify factors that affect the rate of underestimation of ADH. RESULTS The rate of underestimation of ADH was found to be 48% (21 of 44 lesions). Underestimation of ADH was significantly less frequent for lesions evaluated with 11-gauge vacuum-assisted biopsy than for lesions evaluated with 14-gauge automated gun biopsy (22% [four of 18 lesions] vs 65% [17 of 26 lesions], p = 0.012). The other clinical, sonographic, and biopsy features examined did not affect the rate of underestimation of ADH. CONCLUSION For sonographically guided core biopsy of the breast, the rate of underestimation of ADH was 48%. This rate was lower for lesions evaluated with 11-gauge vacuum-assisted biopsy (22%) than for those evaluated with 14-gauge automated gun biopsy (65%). This finding was particularly true of smaller lesions (< or = 2.0 cm) and for lesions of the mass-only type.