Headache and focal neurologic deficits in a 37-year-old woman.

A 37-year-old woman presented with progressively worsening headache. She had no headache history, and initial evaluation revealed hydrocephalus of unclear etiology. A ventriculoperitoneal shunt was placed with improvement. However, her headache returned and she developed neurologic deficits. Imaging studies demonstrated multiple cystic lesions in the posterior fossa. Serum and cerebrospinal fluid studies were unrevealing and a biopsy of the cystic lesions was performed. The clinical approach, differential diagnosis, and neuropathological findings are discussed.