[Sonographic features of breast imaging reporting and data system assessment category 4 and 5 non-palpable breast...

To evaluate the diagnostic value of the sonographic features of Breast Imaging Reporting and Data System (BI-RADS) assessment category 4 and 5 non-palpable breast lesions.

A total of 213 non-palpable breast lesions that were pre-operatively assessed to be BI-RADS category 4 and 5 lesions by ultrasound were enrolled in this study. The diagnostic value of their sonographic features were assessed by using pathologic results as the golden standards.

Of these 213 lesions, 128 (60.1%) were pathologically confirmed to be benign and 85 (39.9%) to be malignant. The mean size was not significantly different between the benign and the malignant lesions (P=0.09). The sensitivity of "irregular shape" for diagnosing breast cancer was 89.9%, while the sensitivities of other sonographic features ranged from 7.6% to 42.4%. The diagnostic specificities were high for "angular margin", "microlobular", "spiculation" and "abundant flow" (89.0%-95.6%). The common sonographic findings of benign lesions included "irregular shape" (66.7%), "obscure margin" (35.1%), "shadowing" (27.2%), and "taller-than-wider" (26.3%).

"Irregular shape" is the most sensitive sonographic feature in the diagnosis of malignant BI-RADS category 4 and 5 non-palpable breast lesions. Ultrasound can accurately identify the invasive margin features of breast cancers, which is especially useful for the diagnosis of BI-RADS category 5 lesions.