The cytopathology of reactions to ventricular shunts.

A common cause of malfunctioning ventricular shunts is the occlusion of either tip by a variety of normal or reactive tissues and foreign substances. A six-year-old girl with communicating hydrocephalus and a meningomyelocele, a 48-year-old man with an ependymoma and an 11-year-old boy with a pineal germinoma had multinucleated histiocytic giant cells and ependymal cells in cerebrospinal fluid obtained from their ventricular shunts. These cellular changes were interpreted as the cytologic counterpart of the foreign-body inflammatory reactions often seen histologically on occluded shunt tips. Numerous clusters of benign choroid plexus epithelium were found in an ascitic fluid from a six-year-old girl with an optic nerve glioma and a ventriculoperitoneal shunt. Such embolism of normal tissues must be distinguished from metastases from intracranial neoplasms.