What percentage of Breast Imaging-Reporting and Data System (BI-RADS) 2 breast lesions are benign after biopsy?

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Last updated: March 26, 2025 • View editorial policy

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From the Guidelines

Approximately 98% of BI-RADS 2 breast lesions are benign after biopsy. BI-RADS 2 lesions are categorized as "benign findings" and generally do not require biopsy as they are considered to have a less than 2% risk of malignancy, as recommended by the NCCN clinical practice guidelines in oncology 1. When biopsies are performed on BI-RADS 2 lesions, the vast majority confirm the benign nature of these lesions.

Key Points

  • Common BI-RADS 2 findings include simple cysts, fibroadenomas, lipomas, intramammary lymph nodes, and benign calcifications.
  • These lesions typically have well-defined characteristics on imaging that strongly suggest benignity, such as smooth margins, homogeneous internal echoes, and absence of suspicious features.
  • The NCCN panel recommends resuming routine screening for BI-RADS category 1 (negative finding) or category 2 (benign) lesions 1.
  • Routine screening mammography should continue at appropriate intervals to monitor for any changes.
  • The high benign rate after biopsy reinforces the accuracy of the BI-RADS classification system in identifying truly benign lesions. Some key considerations for BI-RADS 2 lesions include:
  • Patient anxiety or physician caution may lead to biopsy, despite the low risk of malignancy.
  • Specific clinical concerns, such as a strong family history of breast cancer, may also prompt biopsy.
  • The NCCN guidelines emphasize the importance of concordance between pathology reports and imaging findings when a biopsy is performed 1.

From the Research

Breast Imaging-Reporting and Data System (BI-RADS) 2 Lesions

  • The frequency of malignancy in breast lesions classified as BI-RADS 2 is zero, as reported in a study published in 2015 2.
  • A study from 2015 found that 0 out of 192 (0%) lesions classified as BI-RADS 2 were malignant, with histopathology available in 67 (34.9%) lesions revealing benign findings exclusively, and the remaining 125 (65.1%) lesions not exhibiting changes during the follow-up period 2.
  • There is no direct evidence in the provided studies regarding the percentage of BI-RADS 2 breast lesions that are benign after biopsy, but the study from 2015 suggests that BI-RADS 2 lesions are highly likely to be benign 2.

Benign Breast Lesions

  • A 2022 study found that approximately 50% (n = 250) of breast biopsy cases were benign 3.
  • A 2006 study reported that 156 patients had a benign breast biopsy, with 20 patients (13%) requiring a subsequent biopsy during the 2-year follow-up 4.
  • The provided studies do not directly address the percentage of BI-RADS 2 lesions that are benign after biopsy, but they suggest that a significant proportion of breast lesions are benign 2, 4, 3.

BI-RADS Classification

  • The BI-RADS classification system is used to categorize breast lesions based on their likelihood of being malignant 2, 3.
  • A study from 2025 investigated the histopathological diagnosis of benign breast masses classified into BI-RADS IVc and V subgroups, but did not provide information on BI-RADS 2 lesions 5.
  • The studies suggest that the BI-RADS classification system is useful in identifying benign breast lesions, but do not provide direct evidence on the percentage of BI-RADS 2 lesions that are benign after biopsy 2, 5, 3.

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

2
Research

Benign (BI-RADS 2) lesions in breast MRI.

Clinical radiology, 2015

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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