Breast US in patients who had microcalcifications with low concern of malignancy on screening mammography.

PURPOSE: To review ultrasound (US) findings in patients who have suspicious microcalcifications with low concern of malignancy (BI-RADS category 4A) on screening mammography and to evaluate helpful findings in differentiating benign and malignant lesions.
MATERIALS AND METHODS: Between August 2005 and July 2006, 192 patients showed microcalcifications only, without mass or associated density, on screening mammography. Among them, we selected 82 patients who had microcalcifications with low concern of malignancy (category 4A) that were pathologically confirmed by surgical excision after wire localization (n=23) or biopsy (n=59). Breast US was performed in 37/82 cases and we analyzed the US findings for the calcification areas in these patients, evaluating the findings with benign or malignant pathological results. We correlated US findings with mammographic calcifications using mammography-guided 2D-localization for the calcifications before US examination.
RESULTS: There were 12 malignant lesions (32.4%) including 3 invasive ductal carcinomas (IDC), one microinvasive ductal carcinoma (MIDC), 8 ductal carcinoma in situ (DCIS) and 25 benign lesions (67.6%) including 2 atypical ductal hyperplasias (ADH). IDC showed calcifications within heterogeneous hypoechoic parenchyma or calcifications within complex hypoechoic masses of taller-than-wide shape on US. One MIDC showed calcifications within heterogeneous hypoechoic parenchyma and six DCIS showed negative findings, or calcifications with a small nodule, or only calcifications on US. The most common positive US finding in benign lesions was cysts with calcifications. In 24/37 cases (64.8%) with negative US findings, 18 (75%) were benign lesions and 6 (25%) were DCIS.
CONCLUSION: In patients with category 4A microcalcifications without associated findings on screening mammography, negative US findings had a high rate of benign results (18/24, 75%). Visible calcifications within heterogeneous hypoechoic parenchyma or mass on US increased the probability of malignancy.