Are Benign Core Needle Biopsy Results Really Benign in BIRADS 4 and 5 Breast Lesions?

Background: When malignancy is suspected in a breast mass through imaging methods, a core needle biopsy (CNB) is the first-choice minimally invasive method. However, it may cause diagnostic errors as only part of the mass is sampled. Objectives: The present study aimed to determine the frequency of radiologic-pathologic discordance with CNB, evaluate the upgrade rates to malignancy in excised patients, and examine benign conditions that may be radiologically confused with malignancy. Patients and Methods: A retrospective review was conducted on 986 patients who underwent breast biopsy between 2020 and 2023. The study included 73 female patients who had no evidence of malignancy with CNB but underwent excision/lumpectomy due to ongoing clinical-radiologic-pathologic suspicion or social indications. Excisional biopsy (EB) results were classified as benign, borderline, and malignant. Univariate and multivariate logistic regression analyses were performed to identify factors associated with discordance. Results: Malignancy was detected in 19 (26%) of a total of 73 discordant benign lesions after EB. One borderline and 53 benign pathologies were detected by EB. There is a statistically significant difference between malignant and benign-borderline groups in age (P = 0.011), presence of suspicious microcalcification (P = 0.001), and Breast Imaging Reporting and Data System (BIRADS) category (P = 0.013). There are no differences between the malignant and benign-borderline groups for tumor size, family history, and suspicious findings on sonographic and magnetic resonance imaging (MRI). Conclusion: In breast masses where malignancy is suspected based on clinical and imaging findings, CNB is a reliable method with high diagnostic accuracy. However, additional surgery is required when there is clinical and radiologic discordance with the CNB findings.