Borderline breast lesions diagnosed at core needle biopsy: can magnetic resonance mammography rule out associated malignancy? Preliminary results based on 79 surgically excised lesions.

The purpose of this study is to assess whether magnetic resonance mammography (MRM) can exclude associated malignancy in case of diagnosis of borderline breast lesions (B3) at core needle biopsy (CNB). Retrospective analysis of MRM findings of 79 borderline breast lesions (26 benign papillomas, 29 radial sclerosing lesions, 6 atypical ductal hyperplasias, 18 lobular neoplasias) diagnosed at CNB was performed. Lesions were classified as "non-suspicious" or "suspicious" according to Fischer score. These findings were compared to the results of histological analysis of the excisional specimens. Sensitivity, specificity, positive (PPV) and negative (NPV) predictive values of MRM in predicting the presence of malignancy were calculated. Out of 24 (30.4%) lesions classified as "suspicious", 8 (33.3%) proved to be malignant and 16 (66.7%) benign. Among the 55 (69.6%) "non-suspicious" lesions, only 1 (1.8%) was malignant (low-grade ductal carcinoma in situ), while the remaining 54 (98.2%) proved to be benign. MRM sensitivity, specificity, PPV, and NPV were 88.9%, 77.1%, 33.3%, and 98.2%, respectively. When a borderline lesion is diagnosed on CNB, in case of mild or no enhancement at MRM, follow-up rather than excisional biopsy might be prompted.