Recurrent glioependymal cyst of the posterior fossa: an unusual entity containing mixed glial elements. Case report.

Reports of glioependymal cysts in the posterior fossa are uncommon. There are only a few documented cases of posterior fossa glioependymal cysts and, to our knowledge, this is the first documented case of a recurrent posterior fossa glioependymal cyst. We discuss the clinical presentation, pathological features, and treatment options for this lesion. A 55-year-old woman with a 10-year history of a recurrent cytic lesion in the left cerebellar hemisphere, which required two operations, presented with diplopia, dizziness, and ataxia. Magnetic resonance imaging revealed a multiloculted cytic lesion in the left cerebellar hemisphere. Resection, through a suboccipital craniectomy, resulted in improvement of the patient's neurologic status. Microscopic examination of a surgical specimen revealed complex cysts lined by a single layer of ependyma-like cells and underlying gliotic parenchyma with florid reactive changes. Glioependymal cysts of the posterior fossa may present with symptoms of increased intracranial pressure and compression of local structures. Recurrence in this case may be partly explained by subtotal resection in the previous two operations and may also be associated with a florid, proliferative ependymal element. Definitive diagnosis is by microscopic examination of surgically resected specimens. Total extirpation of these cystic lesions is recommended.