Purpose: To assess the malignant/high-risk upgrade rates of discordant biopsies performed at one institution over a 5-year time period and to compare the malignant discordant rates for stereotactic, ultrasound guided and MRI guided biopsies.
Materials and Methods: Methods and Materials: Retrospective chart review of all discordant breast core needle biopsies (CNB) performed at an academic institution in an urban setting, for a period of 5 years. Biopsy results and surgical pathology results were reviewed. Malignant discordant rates were calculated and compared for stereotactic, ultrasound guided and MRI guided biopsies using chi square test.
Results: 210 breast image-guided CNB yielded benign and discordant results. Overall rate of malignant plus high-risk pathology on surgical excision was 32% ( 67/210).Malignancy rates based on surgical pathology were overall 15.2% ( 32/210); modality specific malignancy rates were: 21.6% (23/106) for ultrasound-guided CNB, 8.3 % (7/84) for stereotactic and tomosynthesis guided CNB and 10% (2/20) for MRI guided CNB, with statistically significant difference in proportion of malignancy upgrade rate based on CNB imaging modality, X2= 9.92, p=0.007, highest upgrade rates for US guided CNB. Most common diagnosis on excision for ultrasound guided CNB was invasive ductal carcinoma (36%), for stereotactic biopsies was DCIS (75%) and MRI biopsies was invasive ductal carcinoma (100%). Additionally, it was observed that 41/210 cases underwent MRI for known malignancy in ipsilateral or contralateral breast. In 50% of these cases, no MRI enhancement was seen at the site of discordant biopsy, 100% of these cases were benign on surgical excision.
Conclusion: Despite recent advances in breast imaging techniques and image guided biopsy, malignancy upgrade rate and overall high rate of malignant and high -risk pathology supports the continued importance of radiologic-pathologic correlation. Identification of high-risk lesions can inform the need for future high-risk screening. Ultrasound guided CNB had the highest malignant discordant rates. Despite lack of real time verification of adequate target sampling, MRI guided CNB does not appear to be associated with higher malignant discordant rates. MRI may have a vital role in the management of benign discordant biopsies where absence of suspicious enhancement can be used to support deferred surgical excision and close imaging follow up.
Clinical Relevance Statement: Radiologic-pathologic review remains a valuable tool for all image guided biopsies. Given the high rate of malignant/high risk discordance, all benign discordant biopsies should undergo surgical excision. Additionally, MRI can be a valuable tool which can help defer surgical excision in benign discordant biopsies.
