High-Risk Lesions at MRI-Guided Breast Biopsy: Frequency and Rate of Underestimation

OBJECTIVE. The purpose of this article is to determine the underestimation rate of highrisk lesions diagnosed at MRI-guided breast biopsy. MATERIALS AND METHODS. This was a retrospective review of 446 MRI-guided breast biopsies from January 2006 through December 2010. Data were collected on examination indication, lesion size and type, and pathology results. Biopsies were performed with a 9-gauge vacuum-assisted device. Biopsy results of atypical ductal hyperplasia (ADH), papillary lesion, radial scar, lobular neoplasia, and atypia were identified and compared with final excisional pathology results. Underestimation rates were calculated and data were compared by patient and lesion characteristics using chi-square analysis. RESULTS. Of the 446 MRI-guided biopsies, 96 (21.5%) were high-risk lesions. Forty two of 96 lesions (44%) were masses, and 54 (56%) showed nonmass enhancement. Twenty of 96 lesions (20.8%) were ADH, nine (9.4%) were lobular neoplasia, 27 (28.1%) were papillary lesions, 20 (20.8%) were radial scar, and 20 (20.8%) were other atypias. Sixty-nine of 96 lesions (71.9%) had surgical excisional pathology results available. Sixteen of 69 (23.2%) lesions were upgraded to malignancy; 11 of the 16 (68.8%) were upgraded to ductal carcinoma in situ (DCIS) and five 931.2%) were upgraded to invasive carcinoma. The underestimation rate was 31.6% (6/19) for ADH, 5.9% (1/17) for papillary lesions, 23.1% (3/13) for radial scar, 28.6% (2/7) for lobular neoplasia, and 30.8% (4/13) for other atypias p = 0.43). There was no statistically significant difference in underestimation rate by lesion type, size, or history of newly diagnosed breast cancer. CONCLUSION. MRI-guided breast biopsy yielded high-risk lesions in 21.5% of cases, and the underestimation rate was 23.2%. No patient or lesion characteristics correlated with underestimation rate.