Choroid plexus carcinoma. Cytologic identification of malignant cells in ascitic fluid.

Abdominal deposits of a choroid plexus carcinoma in a patient with a ventriculoperitoneal shunt were cytologically diagnosed by examination of ascitic fluid after regression of the primary tumor. The morphology of the malignant cells in ascitic fluid was more similar to that of mesothelial cells than to the appearance of cells from this lesion in cerebrospinal fluid.