We investigated the ultrasonographic (US) appearance of metaplastic squamous breast carcinoma with the pathologic correlation.

During an 8-year period, the US appearances of 10 patients with metaplastic squamous breast carcinoma were retrospectively analyzed on the basis of the Breast Imaging and Reporting Data System (BI-RADS) - US lexicon. These 10 patients included 9 patients having invasive adenocarcinomas of the breast with more than 30% squamous metaplasia, and one patient had pure primary squamous cell carcinoma. We correlated the US findings with the pathologic findings.

On US, the majority of the tumors showed oval shapes (70%), indistinct margins (50%), parallel orientation (80%), echogenic halos (60%), complex echogenicity with solid and cystic components (60%), and posterior enhancement (70%). The findings of calcifications (20%) and metastatic axillary lymph nodes (10%) were rare. On pathologic examination, half of the tumors showed infiltrative microscopic margins. All six cases showing complex echogenicity with solid and cystic components on US were pathologically related to the cystic or necrotic portion, and three of these cases had hemorrhage.

On US, metaplastic squamous breast carcinoma mainly manifested as oval, complex, echoic masses with indistinct margins and posterior enhancement that was pathologically related to the cystic or necrotic portions.