Beyond BI-RADS: Nonmass Abnormalities on Breast Ultrasound

Area of Science:

• Radiology
• Oncology
• Medical Imaging

Background:

• Nonmass lesions on breast ultrasound (US) are common findings.
• Current American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS) 5th edition for US does not include the term 'nonmass'.
• Asian researchers have investigated these features, but clinical adoption requires standardization.

Purpose of the Study:

• To discuss the concept of nonmass lesions in breast ultrasound.
• To highlight the need for standardized terminology and evidence for BI-RADS inclusion.
• To review current classifications and potential malignancy indicators.

Main Methods:

• Review of existing literature and guidelines, including Japan Association of Breast and Thyroid Sonology.
• Analysis of nonmass lesion subtypes and their characteristics.
• Discussion of criteria for malignancy and diagnostic implications.

Main Results:

• Nonmass abnormalities are classified into five subtypes: ductal abnormalities, hypoechoic areas, architectural distortion, small cysts, and echogenic foci.
• Focal/segmental distribution and calcifications can suggest malignancy.
• Intraductal, invasive ductal, and lobular carcinomas may present as nonmass lesions.

Conclusions:

• The nonmass concept requires standardized terminology, an interpretation algorithm, and outcome-based evidence for BI-RADS integration.
• Wider clinical acceptance necessitates robust data for both screening and diagnostic US.
• Further research is crucial for accurate diagnosis and management of nonmass lesions.