Incidental detection of probably benign breast masses on screening ultrasound: is follow up an acceptable alternative to biopsy?

Abstract

Purpose: To determine whether nonpalpable solid breast masses that were incidentally detected on screening ultrasound and which were subsequently classified as probably benign can be safely managed with follow-up. Materials and methods: In 438 women 479 nonpalpable solid masses were incidentally detected and classified as probably benign at ultrasound, according to sonomorphologic criteria listed in the BI-RADS category 3 for ultrasound; at mammography these masses were either partially or completely obscured by dense fibroglandular tissue. 476 of the 479 masses were followed, while in the other three masses biopsy was performed after initial imaging. False negative rates, negative predictive values and exact 95% confidence intervals were calculated. Results: 473 of the 476 lesions remained stable at follow-up (range, 2–5 years; mean 3.3 years). Two masses increased (fibroadenomas at biopsy). One mass became palpable and cancer was diagnosed at biopsy. The three initially biopsied masses were fibroadenomas. The false negative rate was 0.2% (1 out of 479; negative predictive value 99.8%, confidence interval 0–1.23%). Conclusion: Follow-up sonography appears to be an acceptable alternative to biopsy for solid masses with benign morphologic features at ultrasound due to the extremely high negative predictive value (99,8%).