Echogenic Rind Associated With Suspicious Masses on Ultrasound: Performance for Breast Cancer Diagnosis and...

BACKGROUND. The 6th edition of the BI-RADS ultrasound lexicon is anticipated to include echogenic rind as a renamed associated feature, defined as a thick hyperechoic band partially or completely surrounding a mass and disrupting surrounding tissue texture. OBJECTIVE. The purpose of this study was to assess the performance of an echogenic rind associated with a suspicious mass on breast ultrasound for breast malignancy diagnosis as well as associations of echogenic rind with pathologic tumor characteristics. METHODS. This retrospective study included patients who underwent both diagnostic breast ultrasound that showed a suspicious mass (BI-RADS category 4 or 5) and subsequent ultrasound-guided biopsy from July 1, 2022, to June 30, 2023. Two radiologists independently reviewed the ultrasound examinations for echogenic rinds (requiring circumferential extent ≥ 25%) associated with masses; the readers also measured masses without and with inclusion of echogenic rinds. Diagnostic performance was evaluated using histopathology as the reference. RESULTS. The study included 511 patients (mean age, 52 years) with 583 suspicious masses; 249 masses were diagnosed as breast malignancy. The presence of echogenic rind yielded sensitivity and specificity, respectively, for breast malignancy of 58% and 81% for reader 1 and 51% and 85% for reader 2. An echogenic rind was associated with invasive cancer for reader 1 (invasive ductal carcinoma [IDC], 62%; invasive lobular carcinoma [ILC], 57%; ductal carcinoma in situ [DCIS], 24%; p = .003) and reader 2 (IDC, 53%; ILC, 53%; DCIS, 18%; p = .03). An echogenic rind was associated with invasive cancer molecular subtype for reader 1 (luminal A, 66%; luminal B, 48%; HER2-enriched, 100%; basal-like, 25%; p = .002) and reader 2 (luminal A, 62%; luminal B, 32%; HER2-enriched, 67%; basal-like, 19%; p < .001). In 168 resected malignancies, the difference between pathologic tumor size (mean, 19 mm) and ultrasound-based mass size, without and with the inclusion of echogenic rinds, was 4 and 3 mm for reader 1 and 7 and 5 mm for reader 2, respectively. CONCLUSION. An echogenic rind serves as a more specific than sensitive indicator of breast malignancy. Among breast malignancies, the finding is associated with invasive cancer. Inclusion of the rind decreases underestimation of tumor size relative to surgical pathology. CLINICAL IMPACT. These results provide insights into the clinical implications of an echogenic rind on ultrasound.