Newborn with an abdominal mass

CT of retroperitoneal teratoma
Axial (above), coronal (below left), and sagittal (below right) CT with contrast of the abdomen shows a large left-sided abdominal mass which arises from the retroperitoneum and crosses the midline and which displaces the left kidney inferiorly and posteriorly. The mass is heterogenous in nature and contains fat, is predominantly solid but has some cystic components, and it enhances minimally.

The diagnosis was retroperitoneal teratoma.