From the Guidelines
Approximately 2% of BI-RADS 3 lesions are ultimately found to be malignant. This low malignancy rate is why BI-RADS 3 lesions are classified as "probably benign" and typically managed with short-term follow-up imaging rather than immediate biopsy 1. The standard protocol for BI-RADS 3 findings involves follow-up imaging at 6,12, and 24 months to ensure stability of the lesion. If any concerning changes occur during surveillance, the lesion may be upgraded to a higher BI-RADS category requiring biopsy.
Key Points
- The low malignancy risk reflects the specific imaging characteristics of these lesions that are not typical of cancer but cannot be definitively classified as benign.
- Common examples of BI-RADS 3 findings include certain non-calcified circumscribed masses, focal asymmetries, and some clusters of round calcifications.
- This approach balances the need to detect early malignancies while avoiding unnecessary biopsies for the vast majority (98%) of patients with benign findings.
Management
- For BI-RADS category 3 lesions, diagnostic mammograms are recommended at 6 months, then every 6 to 12 months for 1 to 2 years as appropriate 1.
- If the lesion remains stable or resolves mammographically, the patient resumes routine screening intervals for mammography.
- If the lesion increases in size or changes its benign characteristics, a biopsy is then performed.
Considerations
- The exception to this approach of short-term follow-up is when a return visit is uncertain or the patient strongly desires biopsy or has a strong family history of breast cancer 1.
- In those cases, initial biopsy with histologic sampling may be a reasonable option.
From the Research
Malignancy Rates of BI-RADS 3 Lesions
- The malignancy rate for growing BI-RADS category 3 lesions is 4.9% 2.
- For MRI-detected probably benign (BI-RADS 3) lesions, the malignancy rate is low, with one study reporting a rate of 0.9% 3.
- The incidence of malignancy of followed up synchronous BI-RADS category 3 lesions was 1.0% at 6 months and 2.2% at 30 months 4.
- A study of mammographic BI-RADS 3 lesions found a cancer detection rate of 0.65%, which is less than the recommended 2% threshold 5.
- The malignancy rate for BI-RADS category 3 lesions detected on screening breast ultrasound was 0.7%, with a higher rate of 2.2% for patients with abnormal mammograms and 0.4% for those with normal mammograms 6.
Key Findings
- Sonographic morphological changes and suspicious mammographic features are associated with malignancy in BI-RADS category 3 lesions 2.
- Short-term follow-up MRI at intervals of 6,12, and 24 months can be used to detect suspicious lesions 3.
- Monitoring can be proposed for synchronous BI-RADS category 3 lesions detected in preoperative breast cancer patients, with continued follow-up beyond 2 years potentially being beneficial 4.
- Careful evaluation is required to avoid unnecessary short-interval follow-up or biopsy for BI-RADS category 3 lesions 6.