Underestimation of atypical ductal hyperplasia at MRI-guided 9-gauge vacuum-assisted breast biopsy

OBJECTIVE. The purposes of this study were to determine the frequency of diagnosis of atypical ductal hyperplasia (ADH) at MRI-guided 9-gauge vacuum-assisted breast biopsy and to assess the rate of underestimation of ADH at subsequent surgical excision. MATERIALS AND METHODS. We conducted a retrospective review of medical records of 237 lesions consecutively detected with MRI and then subjected to MRI-guided 9-gauge vacuum-assisted breast biopsy during a 33-month period. Underestimated ADH was defined as a lesion yielding ADH at vacuum-assisted biopsy and cancer at surgery. Scientific tables were used to calculate 95% CI. RESULTS. Histologic analysis of MRI-guided vacuum-assisted breast biopsy specimens yielded ADH without cancer in 15 (6%) of 237 lesions. Among 15 patients in whom vacuum-assisted breast biopsy yielded ADH, the median age was 52 years (range, 46-68 years). The median number of specimens obtained was nine ( range, 8-18 lesions). Median MRI lesion diameter was 1.3 cm (range, 0.7-7.0 cm). Among 15 MRI lesions, 10 (67%) were nonmasslike enhancement and five (33%) were masses. Surgical excision was performed on 13 lesions. Surgical histologic findings were malignancy in five (38%) of the cases, all ductal carcinoma in situ; high-risk lesion in six (46%) of the cases, including ADH without other high-risk lesions (n = 2), ADH and lobular carcinoma in situ (LCIS) (n = 1), ADH, LCIS, and papilloma (n = 1), ADH and papilloma (n = 1), and LCIS (n = 1); and benign in two (15%) of the cases. These data indicated an ADH underestimation rate of 38% (95% CI, 14-68%). CONCLUSION. ADH without cancer was encountered in 6% of MRI-guided 9-gauge vacuum-assisted breast biopsies. ADH at MRI-guided vacuum-assisted breast biopsy is an indication for surgical excision because of the high (38%) frequency of underestimation of these lesions.