Neurenteric cyst with xanthomatous changes in the prepontine area: unusual radiological findings.

Preoperative diagnosis of neurenteric cysts can be difficult because the imaging findings of a neurenteric cyst may be similar to those of an arachnoid cyst. The authors report a case of a neurenteric cyst with xanthomatous changes in the prepontine area. This 4-year-old girl was admitted to their institution with intermittent neck pain and vomiting. Computed tomography showed a hypodense mass in the prepontine area. Magnetic resonance imaging showed a cystic lesion measuring approximately 4 x 3 cm. The brainstem was displaced posteriorly, and the cisterns in both cerebellopontine angles were widened. The signal intensity of the cyst was similar to that of cerebrospinal fluid. Adjacent to the basilar artery there was a solid component of the mass that enhanced after administration of Gd. Intraoperatively, the authors found a cystic mass containing clear fluid with a yellowish solid nodule. On the basis of histopathological findings, the lesion was diagnosed as a neurenteric cyst with xanthomatous changes.