Increased intracranial pressure and hydrocephalus in a teenager

An otherwise healthy 15-year-old male was transferred from another hospital to our institution on March 28, 1997, because of the rapid onset of signs compatible with increased intracranial pressure (ICP) and the presence of hydrocephalus on a computerized tomography (CT) scan of the head. He had been adopted from Bolivia in 1983 and had not left Western Europe nor had close contacts with individuals from developing countries during this time period. Two months earlier, he had suffered from spontaneously resolving headache, fever, nausea, and vomiting that had been attributed to a viral meningitis (sterile CSF with transient lymphocytic pleiocytosis and elevated proteins). On admission to our hospital, magnetic resonance imaging (MRI) revealed a solitary 1.5 cm round cystic lesion in the left lateral ventricle that was not visible on the CT. It was attached to the choroid plexus and obstructed CSF circulation (see figure). Because of clinical deterioration, the patient rapidly underwent surgical ventriculostomy for drainage and removal of the cyst. Histology established the diagnosis.