Newborn with an abdominal mass

US of retroperitoneal teratoma
AXR (left) shows faint calcifications in the middle aspect of the right abdomen. Transverse US (above right) and sagittal US (below right) of the right lower quadrant shows a large primarily cystic mass with some solid components that is medial to and inferior to the right kidney.

The diagnosis was retroperitoneal teratoma.