MRI Findings of Vermian Medulloblastoma

PURPOSE: To find characteristic MRI features of vermian medulloblastoma. MATERIALS AND METHODS: MRI studiesand medical records were retrospectively reviewed for 12 patients with surgically proven midline medulloblastoma. The assessment concerned appearance of the mass in relation to surrounding structures ; MR signal intensity ; the enhancement pattern ; the mass's location and size ; presence of a cystic/necrotic area, calcification, or vascular void ; extension through the foramen Luschka ; degree of hydrocephalus ; and presence of tonsillarherniation. RESULTS: The midline medulloblastoma commonly showed roundish moon-surface appearance, especially onthe axial T2-weighted images. All tumors showed heterogeneous signal intensities mainly due to intratumoralcystic/necrotic or hemorrhagic changes. The tumors were commonly located at mid- and/or inferior vermis. Occasionally the tumors extended through the foramen Luschka, and caused obstructive hydrocephalus of moderate tosevere degree. Post-con-trast study showed heterogeneous, dense contrast enhancement in the majority of patients. CONCLUSION: The MR finding of the moon-surface appearance formed by both the mass and the intratumoralcystic/necrotic change as seen on axial T2-weighted images could be helpful in the diagnosis of vermianmedulloblastoma.

Clear Cell Meninioma: Case Report

Clear cell meningioma is a recently recognized variant of meningiomas. We present a case of a 47-year old man with clear cell meningioma which involved right cerebellar hemisphere. Magnetic resonance imaging revealed a 3(34cm sized well enhanced round nodular lesion with mild mass effect. He underwent suboccipital craniectomy with a successful total removal of the tumor. To our knowledge, this is the first report of clear cell meningioma in our country.