Background: Most cases of breast lesions of uncertain malignant potential (B3) undergo surgical intervention. We aimed to analyze the outcome of B3 lesion subtypes in a large series of screen-detected cases. Methods: We screened 2,986 core needle biopsies to classify B3 lesions. Positive predictive values (PPVs) for malignancy were calculated for a comprehensive risk characterization according to clinicopathologic and morphologic variables. Results: B3 lesions comprised 35% atypical ductal hyperplasia (PPV = 20%), 16.7% flat epithelial atypia (PPV = 12%), 22.7% lobular neoplasia (PPV = 16.2%), 9% papillary lesion (PPV = 18.5%), 8.6% phyllodes tumor (PPV = 3.8%), and 8% radial scars (PPV = 4.1%) based on histopathologic diagnosis. Upgrade rates were 15.9% for calcifications, 13.7% for mass lesions, and 16.7% for architectural deformities, with 8.3% of malignant lesions classified as ductal carcinoma in situ and 6.7% as invasive cancers (PPV = 15%). Conclusion: B3 lesions entail a heterogeneous risk of malignancy, and careful radiologic–pathologic correlation is required for optimal treatment.
NHS Breast Screening multidisciplinary working group guidelines for the diagnosis and management of breast lesions of uncertain malignant potential on core biopsy (B3 lesions)
