Purely cystic form of choroid plexus papilloma with acute hydrocephalus in an infant. Case report.

Infants with acute hydrocephalus often present with nonspecific neurological signs, and cystic choroid plexus papilloma (CPP) is a very rare cause of acute obstructive hydrocephalus. The authors present the case of a 1-year-old girl who became irritable, started vomiting, and became comatose within a day. Magnetic resonance (MR) imaging revealed a cystic lesion in the third ventricle as well as hydrocephalus. Although the aqueduct appeared to be patent, phase-contrast MR imaging showed no pulsatile flow of cerebrospinal fluid in the ventricles. An emergent endoscopic third ventriculostomy was performed. Endoscopic examination revealed a highly mobile cyst attached by a pedicle to the choroid plexus adjacent to the Monro foramen in the lateral ventricle. The cyst was totally excised during the endoscopic procedure and was subsequently diagnosed as a CPP on the basis of histopathological findings. Purely cystic CPP is a very rare pathological entity; however, when it does occur, it can cause obstructive hydrocephalus which, without rapid diagnosis and surgical intervention, could lead to sudden death.