Multimodality Probably Benign (BI-RADS 3) Cases Management and Pitfalls

Probably Benign Cases - BI-RADS Three Category Management and Pitfalls

Sona Chikarmane Assistant Professor of Radiology, Brigham and Women's Hospital

Breast Imaging Division and Associate Chair of Faculty Development, Department of Radiology

Introduction

Today I'll be presenting on probably benign cases or BI-RADS three category management and pitfalls.

Learning Objectives

  • Provide an overview of BI-RADS three findings on breast mammography, ultrasound, and MRI that are currently accepted as probably benign.
  • Present a pictorial review of BI-RADS three lesions.
  • Discuss the appropriate and inappropriate uses of the probably benign category.
  • Highlight some challenging clinical and patient factors that may affect management, including high-risk patient populations, younger patients, and what to do on baseline studies.
  • Provide examples of upgraded and downgraded BI-RADS three lesions on mammography, ultrasound, and MRI and their outcomes and discuss assessment and management lessons.

Topics

Defining Probably Benign

Probably benign findings are breast imaging findings with a less than 2% rate of malignancy. Follow-up with short interval imaging at six months, 12 months, and 24 months instead of biopsy. If there's greater than two years of stability, findings can be deemed benign.

Appropriate BI-RADS Three Assessments in Mammography

  • Case 1: 39-year-old woman, oval circumscribed equal density mass on left CC spot image, negative ultrasound, stable over two years, likely fibroadenoma.
  • Case 2: 64-year-old woman, grouped punctate and round calcifications on baseline screening, appropriate diagnostic evaluation, stable over five years, benign.
  • Case 3: Focal asymmetry on a baseline, two-view finding, concave margins, appropriate diagnostic views, stable over four years, benign.

Inappropriate BI-RADS Three Assessments in Mammography

  • Case 1: 75-year-old woman, new focal asymmetry, negative ultrasound, placed in probably benign category, later found to be invasive lobular carcinoma.
  • Case 2: 73-year-old woman, mass in upper outer breast, incomplete diagnostic workup, negative ultrasound, placed in probably benign category, later found to be invasive ductal carcinoma.
  • Case 3: New circumscribed asymmetry or mass, persisted on spot compression views, negative ultrasound, later found to be invasive ductal carcinoma.

Probably Benign Findings in MRI

The ACR BI-RADS lexicon states that most approaches for assessing a probably benign lesion on MRI are intuitive. The recommended follow-up is repeat imaging at six months, 12 months, and 24 months. The finding can be reassessed as benign if it's smaller or no longer seen.

Appropriate BI-RADS Three Assessments in MRI

  • Case 1: 38-year-old woman, new T2 hyperintense focus of enhancement, decreased in size at six months, resolved at 12 months.
  • Case 2: 52-year-old woman with BRCA mutation, t2 intermediate intensity oval homogeneously enhancing mass, slow kinetics, stable on follow-up.
  • Case 3: 20-year-old woman, homogeneously enhancing mass, benign enhancement kinetics, targeted ultrasound showed hypo echoic mass, found to be a hematoma.

Challenging Cases in MRI

  • Case 1: 48-year-old woman, enhancing focus near lumpectomy bed, increased at 12 months, found to be invasive carcinoma.
  • Case 2: 56-year-old woman, new focus of enhancement, increased at six months, found to be invasive lobular carcinoma.
  • Case 3: 71-year-old woman, focus of enhancement, increased at six and 12 months, found to be invasive carcinoma.

Background Parenchymal Enhancement

  • Case 1: 40-year-old woman, moderate background enhancement with multiple scattered foci, decreased at six months, benign findings.
  • Case 2: 48-year-old woman, diffuse background enhancement, decreased at 12 months, benign findings.

Inappropriate BI-RADS Three Assessments in MRI

  • Case 1: 59-year-old woman, linear non-mass enhancement with washout kinetics, increased at six months, found to be invasive carcinoma.
  • Case 2: Linear clumped non-mass enhancement, stable at six months, increased at 12 months, found to be ductal carcinoma in situ.

Conclusion

For MRI, the probably benign category is not standardized and is still intuitive. With more research and studies, we will be able to better determine appropriate findings for MRI in the probably benign category. It is important to balance the risk of over-biopsy with the need to detect malignancies, especially in high-risk patients.