Medulloblastomas, which invariably arise in the posterior fossa, must be considered. Prevalence is about 1 in 200 000, accounting for 6% to 8% of all central nervous system tumors. Predominantly encountered in children, medulloblastomas account for only 0.4% to 1% of adult primary brain neoplasms, with the affected adults usually between the ages of 20 and 40 years.1,6,11,12 In one of the largest clinical series of 532 cases, more than 75% were well-circumscribed tumors in the vermis that could disseminate through cerebral spinal fluid spaces.11 Involvement of lateral cerebellar hemispheres is less frequent and usually seen in adults. Truncal ataxia and spasticity present in patients with midline tumors, while limb ataxia and dysdiadochokinesia are associated with lateral tumors. Headache and sixth nerve palsy are also common manifestations. Disabling symptoms usually develop within 3 months. Computed tomography lesions almost always show hyperattenuation and homogenous enhancement.1,6,12 In 2 reviews of 420 and 233 patients, 89% showed CT hyperattenuation and 97% demonstrated enhancement, respectively.12 Magnetic resonance imaging lesions show T2 hyperintensity and T1 isointensity or hypointensity and almost always enhance with a heterogeneous pattern.1,6,9,12- 14 Cysts, calcification, or hemorrhage can also be seen. In a review of 9 adult patients, 8 showed enhancement on the MRI.13 Although our patient was well beyond age 40 years, had other symptoms in addition to cerebellar signs, did not demonstrate a well-demarcated enhancing mass on either CT or MRI, and did not have a hyperdense lesion on CT, medulloblastoma remains in the differential diagnosis based on the location of the lesion and the suspicion for a neoplasm.