Histopathologic analysis of BI-RADS category 4a breast lesions diagnosed by ultrasonography

Purpose: We analyzed the histopathologic findings of the patients with ultrasongraphic Breast Imaging Reporting and Data System (BI-RADS) Category 4a breast lesions to determine which patient can be excluded from any invasive, diagnostic procedure in the future. Methods: Of the 180 cases of BI-RADS Category 4a breast lesions that were diagnosed with ultrasonography during a 6 month-period, 132 cases were pathologically confirmed and these were analyzed retrospectively. Four benign cases that did not undergo any further procedure after fine needle biopsy and 6 malignant cases (4.5%) were excluded from this study. Results: Of the 122 cases, 77 cases (63.1%) showed homogeneous benign finding, and 45 cases (36.9%) showed heterogeneous finding that was made up of two or more different pathologic lesions. Fibroadenoma (55.8%) was the most frequent pathologic finding in the cases with homogeneous finding, followed by fibrocystic change (14.3%), and fibrosis (7.8%). The cases with heterogeneous finding presented fibrocystic change (55.5%), microcalcification (48.8 %), ductal hyperplasia (42.2%), and fibroadenoma (31.1%) in the order of frequency. Conclusion: Lesion with heterogeneous histopathologic nature was the most frequent finding defined as category 4a in breast ultrasonography, followed by fibrodenoma, fibrocystic change, microcalcification, and ductal hyperplasia. Refining more specific ultrasonographic findings of these lesions would guarantee that radiologists exclude more benign lesions from category 4a.