BI-RADS Category 4a Lesions of the Breast: Which US Features are More Predictive of Malignancy?

Abstract

Background: The purpose of our study was to evaluate which among the various ACR BI-RADS US descriptors predicted malignancy among breast lesions assessed as category 4a. Materials and Methods: From January 2004 to September 2005, 494 breast lesions in 475 women which were assessed as category 4a on US, which had undergone biopsy/excision and follow-up were included in this study. Two radiologists retrospectively analyzed the US features of the 494 breast lesions based on the BIRADS lexicon. Clinical features of the patients and US descriptors were analyzed according to histopathology results. Results: Of the 494 category 4a lesions, 450 (91.1%) were benign and 44 (8.9%) were malignancy. PPV of category 4a lesions in this study was 8.9%. Among the US features, complex echoic features were more significantly seen in malignancy than benign, 15.9% to 7.5% (p = 0.043). None of the US descriptors showed significant association to malignancy among the category 4a lesions on multivariate analysis. Conclusion: Complex echoic features on US were more significantly seen in malignant lesions with category 4a assessment. Although none of the minor suspicious US features significantly predicted malignancy among category 4a lesions, usage of BI-RADS lexicon and assessment proves to be effective and consistent.