[Neonatal intracranial tumor highly suspected of teratoma in the lateral ventricle consisting of multiple cysts: case report].

Neonatal intracranial teratoma is rare and early attempts at surgical treatment are not usually successful. We describe an exceptionally rare case of neonatal intracranial tumor in the lateral ventricle composed of multiple cysts with little mass content which was highly suspected of teratoma and treated successfully by microsurgery. A 55-day-old male was admitted to our hospital with complaints of convulsive seizure. Examination found no obvious neurological deficit except mild enlargement and bulging of anterior fontanel. There were no abnormal laboratory findings. Computerized tomography with contrast medium revealed an 8 cm multicystic lesion with little mass content in the right lateral ventricle and hydrocephalus. Magnetic resonance imaging showed the cystic content as slightly higher in intensity than CSF on the T1-weighted image and of higher intensity than CSF on the T2-weighted image. The cyst wall was enhanced on T1-weighted image with gadolinium. The aqueduct was obstructed by compression due to the intraventricular cyst. A right occipitoparietal craniotomy was performed, which disclosed a hair in the cyst wall, two huge cysts, and independence of the intracystic lesion from the lateral ventricle. The tumor was removed except for a small part adjacent to the pineal region, from which the tumor had presumably originated. Mature teratoma was highly suspected on the basis of the hair in the cyst wall and histological examination of the specimen, which revealed hamartomatous tissues derived from two germ cell layers. After surgery, his hydrocephalus was improved and convulsive seizures were reduced remarkably. He was discharged ten days later and is being followed up. Reoperation will be performed if regrowth of the residual tumor occurs.