Clinical Implications of Subcategorizing BI-RADS 4 Breast Lesions associated with Microcalcification: A Radiology–Pathology Correlation Study

Abstract: Currently radiologists have the option of subcategorizing BI-RADS 4 breast lesions into 4A (low suspicion for malignancy), 4B (intermediate suspicion of malignancy), and 4C (moderate concern, but not classic for malignancy). To determine the clinical significance of BI-RADS 4 subcategories and the common pathologic changes associated with these mammographic lesions, a retrospective review of 239 consecutive stereotactic-needle core biopsies (SNCB) for microcalcifications was performed. All 239 SNCBs were BI-RADS 4 lesions, and of these, 191 were subcategorized to 4A, 4B or 4C. Ninety-four of 191 (49%) were 4A, 73 (38%) were 4B, and 24 (13%) were 4C. Fibrocystic change was the most common finding (66/239; 28%) followed by ductal carcinoma in situ (DCIS) accounting for 23% of cases. This was followed by columnar cell alteration with or without atypia (47/239; 19%), and fibroadenoma (45/239; 19%). While 70% (17/24) of BI-RADS 4C category lesions were DCIS, only 21% (15/73) of BI-RADS 4B and 10% (10/94) of BI-RADS 4A were DCIS. Without sub-categorization, carcinoma was diagnosed in 23% (55/239) of all cases with BI-RADS 4. Therefore, subcategorizing BI-RADS 4 lesions is important since it not only benefits the patient and clinician in understanding the level of concern for carcinoma, but will also alert the pathologist.