BI-RADS 4 Mammogram Result
A BI-RADS 4 mammogram indicates a suspicious abnormality that requires tissue biopsy because the lesion has a probability of malignancy greater than 2% but less than 95%. 1
What This Category Means
BI-RADS Category 4 represents lesions that do not display obvious mammographic features of malignancy but are suspicious enough that cancer cannot be ruled out by imaging alone. 1 These findings have a wide range of malignancy probability—significantly higher than Category 3 (which has <2% cancer risk) but lower than Category 5 (which has ≥95% cancer probability). 1
Required Next Steps
Tissue biopsy is mandatory for all BI-RADS 4 lesions. 1 The NCCN guidelines specifically recommend:
- Core needle biopsy (CNB) is the preferred method over needle localization excisional biopsy 1
- A specimen radiograph should be obtained if needle localization excisional biopsy is performed 1
- Concordance between pathology results and imaging findings must be confirmed 1
Actual Cancer Risk
The malignancy rate for BI-RADS 4 lesions varies considerably in clinical practice:
- Overall positive predictive value (PPV) for BI-RADS 4 is approximately 21% in diagnostic mammography 2
- In one study of 227 BI-RADS 4 lesions, 44.9% were confirmed malignant on biopsy 3
- BI-RADS 4 can be subdivided into 4A, 4B, and 4C to better stratify risk 2:
Important Clinical Considerations
The BI-RADS category can change based on additional imaging. 1 If both mammography and ultrasonography are performed, the final BI-RADS assessment represents the cumulative findings of both modalities. 1 The overall assessment is always based on the most worrisome finding present when multiple abnormalities are identified. 1
After Biopsy Results
If biopsy shows benign concordant findings: Follow-up mammography every 6-12 months for 1-2 years is recommended before returning to routine screening. 1
If pathology and imaging are discordant: Repeat breast imaging and obtain additional tissue sampling, or proceed directly to surgical excision. 1
If atypical hyperplasia, LCIS, or other high-risk lesions are found: Surgical excision is required. 1
Critical Pitfall to Avoid
Never accept a negative fine needle aspiration (FNA) result for a BI-RADS 4 or 5 lesion without further action. 1 A negative FNA associated with a suspicious mass is discordant and requires either repeat biopsy with core needle technique or surgical excision. 1 This is essential because false negatives can delay cancer diagnosis and adversely affect mortality outcomes.