Predictive value of breast lesions of "uncertain malignant potential" and "suspicious for malignancy" determined by needle core biopsy

Background: The optimum management of patients whose needle core biopsy (NCB) results are of "uncertain malignant potential" (B3) or "suspicious for malignancy" (B4) is unclear. This study correlates B3 and B4 NCB findings with excision histology to determine associated rates of malignancy. Methods: All NCBs categorized as B3 or B4 were identified from a series of 3729 NCBs. Results of biopsies were reported as normal/nondiagnostic (B1), benign (B2), uncertain malignant potential (B3), suspicious but not diagnostic of malignancy (B4), or malignant (B5) according to the B classification system. B3 lesions included atypical intraductal epithelial proliferations (AIEPs), lobular neoplasia, papillary lesions, radial scars, and potential phyllodes tumors. Histological concordance between NCB and excision specimen was analyzed. Results: A total of 211 B3 lesions and 51 B4 lesions were identified during the study period. The open biopsy rate after a B3/B4 finding was 86% (n = 226). The overall rate of malignancy for B3 lesions after excision was 21%. The B3 lesion-specific rates of malignancy were 6% for radial scars, 14% for papillomas, 35% for AIEP, and 44% for lobular neoplasia. Of the patients with a B4 categorization, 90% (44 of 49) were diagnosed with carcinoma after surgery. Those that were "suspicious for ductal carcinoma-in-situ" and "suspicious for invasion" correlated accurately with excision findings in 81% and 89% of patients, respectively. Conclusions: Management of lesions in the B3 categorization must be tailored to the patient because the specific lesion types are associated with highly variable rates of malignancy. A repeat biopsy or a therapeutic wide local excision should be undertaken in lesions with a B4 NCB categorization because such lesions are associated with a particularly high risk of malignancy at excision.