An overview of B coding of breast core biopsy categorisation and management implications

The United Kingdom National Health Service Breast Screening Programme proposes five B categories for reporting breast screening needle core biopsies. The system is also recommended for symptomatic patients and diagnostic vacuum-assisted biopsies. Usually over 90% of biopsies are categorised as normal (B1), benign (B2) or malignant (B5). B3 is a heterogeneous group including atypical intraductal proliferations, classical lobular neoplasia, papillary lesions, radial scars, cellular fibroepithelial lesions and some rarer lesions. It is important to comment on the presence of epithelial atypia in B3 lesions as the risk of malignancy in the excision specimen is higher if atypia is present. Recent United Kingdom guidelines propose more thorough sampling with vacuum-assisted biopsy as an alternative to diagnostic surgical excision for some B3 lesions. B4 is used for lesions suspicious of malignancy. Further investigation is usually needed for B4 lesions. B5 is subdivided into B5a for DCIS and pleomorphic LCIS, B5b for invasive carcinoma, lymphoma, sarcoma, malignant phyllodes tumour and metastases from extramammary malignancies, and B5c for carcinomas that cannot be classified as in situ or invasive. The biopsy result must be discussed at the multidisciplinary meeting in combination with the clinical and radiological findings (the triple approach) to guide patient management.