Postoperative hemicerebellar inflammation mimicking recurrent tumor after resection of a medulloblastoma

EDULLOBLASTOMA is a highly malignant tumor of the posterior fossa that is predominantly seen in children and accounts for 25% of all pediatric intracranial tumors. 16 Magnetic resonance imaging is frequently used to determine accurate staging preoperatively and for early detection of recurrent disease during followup. Medulloblastomas appear hypointense on T1-weighted MR images and demonstrate heterogeneous signal intensity on T2-weighted images. The mass usually enhances upon administration of a contrast agent, but this finding may be variable. 3,23 Recurrence of medulloblastoma is unfortunately very common. Most recurrent disease in children develops in the first 2 years after initial treatment and usually in the posterior fossa. 14,17,22,24 Medulloblastomas frequently disseminate along the cerebrospinal fluid pathways, and evidence of leptomeningeal metastatic spread is present in up to 33% of all cases at the time of diagnosis. 3,24