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[CT and MRI manifestations of pediatric presacral tumors].

BACKGROUND AND OBJECTIVE
The imaging of presacral tumors in children is characteristic. Computed tomography (CT) and magnetic resonance imaging (MRI) have great values in identifying the position, contents and invasion of pediatric presacral tumors before operation. This study was to investigate the CT and MRI features of pediatric presacral tumors, and evaluate the diagnostic values of CT and MRI.


METHODS
The CT and MRI data of 24 pediatric presacral tumors were analyzed together with pathologic results.


RESULTS
Six cases of pediatric presacral tumors were cystic type, with clear margin and complete capsule, and were composed of multi-capsular spaces; on enhanced scan, the capsular wall showed enhancement, while the cystic contents didn't; all these six cases were confirmed benign by pathology. Five cases were solid type and were enhanced inhomogeneously; all were confirmed malignant by pathology. Thirteen cases were cystic-solid type or with obvious necrosis in solid mass. Of the 13 cases, seven were cystic-solid teratoma (including four benign teratomas and three malignant teratomas confirmed by pathology), containing strip calcification, soft tissue and fat; five were endodermal sinus tumors, showing alveolate enhancement; one was neuroblastoma, with macro-lamellar necrosis, extension to the canalis vertebralis and sacrum invasion. Five tumors, including three teratomas, one rhabdomyosarcoma and one endodermal sinus tumor, had unclear margin. Sacrum invasion was found in one teratoma, one rhabdomyosarcoma, one neuroblastoma and one lymphangioma.


CONCLUSIONS
The location and extend of pediatric presacral tumors can by clearly pictured on CT and MRI. Most tumors can be correctly diagnosed according to their imaging features.