What does a BI-RADS 4 or BI-RADS 5 result mean on a breast examination?

2026-09-15

In the BI-RADS (Breast Imaging Reporting and Data System) classification system used in breast diagnostics (mammography, ultrasound, or breast MRI), the BI-RADS 4 and 5 categories denote suspicious lesions or lesions highly suggestive of malignancy, which necessitate histological or cytological sampling (biopsy).

The BI-RADS 4 category indicates a "suspicious abnormality". The probability of malignancy in this group ranges across a broad spectrum (typically between 2% and 95%). For this reason, the category is frequently divided into three subcategories: - BI-RADS 4A: low suspicion for malignancy (approx. 2–10%); - BI-RADS 4B: moderate suspicion (approx. 10–50%); - BI-RADS 4C: high suspicion for malignancy (approx. 50–95%). A BI-RADS 4 classification does not automatically mean breast cancer; in fact, the majority of 4A lesions ultimately prove to be benign, but histological sampling is mandatory to clarify the diagnosis.

The BI-RADS 5 category indicates an abnormality that is "highly suggestive of malignancy". In lesions with such morphology, the probability of malignancy exceeds 95%. In this case, sampling (needle biopsy) is immediately warranted to determine the precise histological type and to establish the treatment plan.

Clinical trials and studies confirm that BI-RADS 4 and 5 category lesions require histological confirmation, and in the higher categories (particularly in the 4C and 5 groups), the positive predictive value and the rate of malignancy are extremely high.

References

  1. Optimising screening intervals and BI-RADS management pathways in ultrasound-based breast cancer screening: real-world evidence from Shenzhen (2018-2023). PMID 42560548
  2. A Retrospective Study of Breast Imaging Reporting and Data System and Histopathological Correlation in Breast Lumps: A Single-Center Experience at R.L. Jalappa Hospital, Kolar, India. PMID 41988595
  3. BI-RADS Categorization As a Predictor of Malignancy PMID 10352614
  4. Institutional Review of BI-RADS 5 and BI-RADS 4C Lesions Over 5 Years Following Surgical Excision: Analysis of Radiology-Pathology Correlation. PMID 42479170
  5. Quantification of the UK 5-point breast imaging classification and mapping to BI-RADS to facilitate comparison with international literature PMID 22011830
  6. PMID 22011830
  7. PMID 10352614

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