Sonography of benign sacral teratoma in utero.

Sacral teratoma is rarely diagnosed in utero. In the case presented, gray-scale sonography revealed a teratoma in utero, demonstrated the proportion of solid and cystic components, and identified calcification. These are important features, since solid tumors lacking calcification are usually malignant, and cystic or complex tumors as well as those with calcification are usually benign.