Freiburg Neuropathology Case Conference: Tumor of the Cerebellum with Mild, Gyriform Enhancement in a 19-Year-Old Patient

Excerpt

A 19-year-old male patient presented with a history of epilepsy with absences and complex-focal seizures, and mild mental retardation. The patient had daily absences but no focal seizures under antiepileptic medication with valproic acid and topiramate. The patient became symptomatic with headache, nausea, vertigo, and blurry vision 3 months earlier. He was admitted to the department of neurology for a diagnostic workup. Electroencephalograph showed unspecific alterations in the right hemisphere but no epileptic patterns. Blood results were normal. As the vertigo responded to positional treatment using the Dix–Hallpike maneuver, the initial diagnosis was benign paroxysmal positional vertigo. The patient was discharged in a stable clinical condition. The patient presented an acute rotatory vertigo to the right, progressive ataxia, and psychomotor dysfunction, after 10 days. Cranial computed tomography (CT) revealed a large infratentorial mass lesion in the right cerebellar hemisphere with compression of the fourth ventricle and aqueduct with incipient occlusive hydrocephalus. On admission to the department of neurosurgery, the patient was awake, oriented, and showed reduced speech production. He had intact cranial nerve function, no nystagmus and no double vision but mild saccadic pursuit, no paresis or sensory deficits. Coordination was intact except for right-sided mild dysmetria in the finger–nose test, and he showed postural instability with undirected tendency to fall in Romberg’s test. Magnetic resonance imaging (MRI) imaging confirmed the presence of a lesion in the right cerebellar hemisphere with inhomogeneous contrast enhancement. Before surgery, the antiepileptic medication was changed from valproic acid to levetiracetam to minimize bleeding complications. Microsurgical resection was performed in the sitting position using a right-sided suboccipital osteoplastic craniotomy. After dural incision and opening of the arachnoid membranes to release cerebrospinal fluid, the well-defined, soft, grayish tumor could be located in the lateral aspect of the right cerebellar hemisphere in proximity to the petrous bone and the tentorium. No attachment to the dura or the cranial nerves was detected. The moderately vascularized tumor was reduced in size by cavitron ultrasonic surgical aspirator in layers up to the tumor–brain border. On microscopic inspection, a gross total resection could be achieved. This was confirmed by postoperative MRI of the brain. Histological workup of the tumor tissue showed a desmoplastic medulloblastoma WHO Grade IV. The patient had an uneventful postoperative course with no new neurological deficit. Cerebellar symptoms such as vertigo and mild nausea were diminished after surgery, and the patient was discharged home 1 week after surgery with a minimal residual gait disturbance and mild dysmetria of the right hand. …