Astrocytoma of the cerebral aqueduct.

The authors report the case of a 9-year-old girl with a low-grade astrocytoma of the mesencephalon that occluded the sylvian aqueduct. Symptoms, signs, and neuroradiological investigations led to the clinical impression of aqueductal stenosis. The presence of a tumor was diagnosed by cerebrospinal fluid cytology and confirmed at postmortem examination. This is the first reported instance of this tumor being diagnosed by cerebrospinal fluid cytology and the third report of a diagnosis in a living patient. The authors stress the value of CSF cytology in evaluating a typical case of hydrocephalus.