The presacral sacrococcygeal teratoma is the most common tumor of the caudal region in children and is more common in females than in males (4:1) Most tumors are benign and are noted at birth Tumors in patients beyond neonatal age have a higher incidence of malignancy Radiography shows a soft tissue mass that arises from the ventral surface of the coccyx Calcifications are present in 60% of presacral sacrococcygeal teratoma and are more common in benign tumors US confirms whether presacral sacrococcygeal teratomas are cystic, solid, or mixed and can also determine impingement on the urinary tract CT or MRI are helpful in confirming the diagnosis, particularly in older children, and demonstrates the content of a tumor, as well as its extent and bone anomalies Tumors with more solid components are more often malignant than those with more cystic components ( Fig 116.21 ) FIGURE 116.21 Presacral teratoma Computed tomographic section of pelvis with contrast medium enhancement shows a large cystic mass (arrows ) The mass contains both fat and calcification, and displaces the rectum anteriorly and laterally, and the bladder anteriorly B, Bladder with Foley catheter; C, calcification; F, fat; R, rectum Nonmalignant Intra-Abdominal Masses Fecaloma