Imaging–histologic discordance at percutaneous breast biopsy

BACKGROUND: The purpose of the current study was to determine the frequency of imaging-histologic discordance at percutaneous breast biopsy and to assess the likelihood of carcinoma in these discordant lesions. METHODS: Percutaneous imaging guided breast biopsy was performed on 1785 consecutive lesions during a 7-year period under stereotactic (n = 1205) or sonographic (n = 580) guidance, using an automated needle (n = 1044) or directional vacuum-assisted probe (n = 741). Lesions were prospectively classified according to the Breast Imaging Reporting and Data System (BI-RADS) as Category 3 (probably benign), Category 4 (suspicious), or Category 5 (highly suggestive of malignancy). Imaging-histologic discordance was considered to have occurred when the percutaneous biopsy histology did not provide a sufficient explanation for the imaging features; in such cases, repeat biopsy was recommended. Medical records, imaging studies, and histologic findings were reviewed. RESULTS: Imaging-histologic discordance was present in 56 of 1785 (3.1%) lesions. The frequency of discordance was significantly higher in our first 2 years of experience with percutaneous biopsy than in later years (18 of 361 = 5.0% vs. 38 of 1424 = 2.7%; P < 0.04) and was significantly higher for lesions that were BI-RADS Category 5 rather than BI-RADS Category 4 (20 of 416 = 4.8% vs. 36 of 1366 = 2. 6%; P < 0.04). The frequency of discordance was significantly lower with the 11-gauge vacuum-assisted probe than other devices for calcifications (7 of 414 = 1.7% vs. 16 of 251 = 6.8%; P = 0.001) but not for masses (6 of 161 = 3.7% vs. 26 of 959 = 2.7%; P = 0.44). Repeat biopsy, performed in 45 discordant lesions revealed carcinoma in 11 (24.4%; 95% confidence intervals, 12.9-39.5%). The frequency of carcinoma was significantly higher among discordant BI-RADS Category 5 than discordant BI-RADS Category 4 lesions (7 of 16 = 43. 8% vs. 4 of 29 = 13.7%; P < 0.04). CONCLUSIONS: Imaging-histologic discordance occurred in 3.1% of lesions that had percutaneous breast biopsy. Imaging-histologic discordance was an indication for surgical excision because of the high (24.4%) prevalence of carcinoma in these lesions.