Choroid Plexus Papillomas and Their Fine Structure

Two cases of benign choroid plexus papilloma are reported, one in the third ventricle in an 8-month-old boy and the other of disseminated choroid plexus papilloma in the cervical spinal leptomeninges occurring after an interval of four years following the removal of choroid plexus papilloma originating in the fourth ventricle in a 7-year-old boy. The ultrastructure of these tumors was demonstrated and compared. Though the benign choroid plexus papilloma closely mimiced the architecture of the normal choroid plexus, the disseminated choroid plexus papilloma had no fenestrations nor pinocytotic vesicles in the walls of the capillaries or endothelial cells and was presumed to have ceased secretion of cerebrospinal fluid.