Since the introduction of the Breast Imaging Reporting and Data System (BI-RADS) for sonography in 2003, its effectiveness in assessing the likelihood of malignancy in sonographic masses has been well-documented and validated [10-13]. The BI-RADS classification system is crucial for guiding decisions regarding biopsies for suspicious lesions.
Category 3 lesions in BI-RADS are defined as having a low probability of malignancy (2% or less), typically recommending short-term imaging surveillance. While biopsy is generally not indicated for category 3 lesions, it may be performed based on physician or patient preference in certain situations. For these category 3 lesions, a benign result from a core needle biopsy is considered a Benign Concordant Diagnosis, while a malignant result is classified as discordant malignant. However, the subjective nature of sonographic interpretation means subtle suspicious features can sometimes be missed, as the final BI-RADS category relies on the radiologist’s experience, training, and adherence to established criteria. Therefore, even for category 3 lesions, a rigorous review of sonographic features based on strict criteria is essential during imaging-pathology correlation to minimize the risk of overlooking malignancies.
BI-RADS category 4 lesions, on the other hand, are recommended for biopsy due to a higher suspicion of malignancy. However, the positive predictive value (PPV) for category 4 lesions exhibits a wide range (3% to 94%), which can be clinically challenging. To address this variability, the fourth edition of BI-RADS introduced optional subcategories within category 4 (4a, 4b, and 4c) to better stratify the likelihood of malignancy [14]. While BI-RADS did not provide specific malignancy risk ranges for these subcategories, guidelines have been suggested, such as 2-10% for category 4a, 11-50% for category 4b, and 51-95% for category 4c, as proposed by Bent et al. [15]. Studies have shown varying PPVs for these subcategories, with one study reporting PPVs of 6%, 15%, and 53% for categories 4a, 4b, and 4c, respectively, in mammography and sonography [11]. Another study focused on sonography reported higher PPVs of 26%, 83%, and 91% for categories 4a, 4b, and 4c, respectively [13]. This interobserver variability and inconsistent risk stratification highlight the need for clearer and more objective criteria for defining these subcategories. Given the optional use of subcategories and limited clinical data, standardized management protocols are still evolving.
According to BI-RADS guidelines [14], a benign concordant diagnosis can be considered when a core biopsy of a category 4a lesion yields benign results. Conversely, a malignant core biopsy result would be discordant malignant in this category. For category 4c lesions, a benign core biopsy result is typically considered discordant benign, while a malignant result is concordant malignant. Category 4b lesions require careful imaging and pathologic correlation due to the intermediate risk of malignancy. Further research is necessary to fully evaluate the role of these subcategories in refining risk assessment and guiding clinical decision-making.
In conclusion, meticulous imaging-pathology correlation and appropriate post-biopsy management are fundamental to the success of a core biopsy program. This approach is crucial for the early detection of false-negative results after core needle biopsy by proactively identifying discordant lesions, thereby preventing delays in cancer diagnosis. Effective communication between radiologists and pathologists is the cornerstone of imaging-pathology correlation; however, establishing concordance relies heavily on the radiologist’s expertise. The radiologist performing the biopsy must possess a comprehensive understanding of the imaging characteristics of various pathologic breast lesions and be adept at correlating these findings with pathology results to ensure accurate diagnoses and optimal patient care.
