Papillomas of the Choroid Plexus

Abstract

p APILLOMAS of the choroid plexus are solitary reddish grey tumors attached to the choroid plexus. The irregular surface is covered by a thin transparent capsule, and the firm tumor occasionally is partly calcified. Microscopically, papillomas resemble normal choroid plexus, being composed of columnar or cuboidal epithelium supported by highly vascularized connective tissue. They are usually benign but may undergo malignant transformation. 7,n,~,24 They are occasionally multiple and may metastasize by way of the cerebrospinal fluid regardless of their ventricular location.3,1~,2~,2a In order of frequency papillomas are located in the fourth ventricle, atrium of the lateral ventricle, and the third ventricle. In infants and the younger age groups they are most often found in the lateral ventricle; in adults, in the fourth ventricle. 4,7,~~ Although they occur in any age group, even in the newborn, 7 they show a predilection for the younger age group with the greatest incidence in the first decade of life. 7,~6,1s They are slightly more common in males 22 and have been found in a brother and sister? ~ Papillomas of the choroid plexus account for 0.4 to 0.6% of all brain tumors.6,9,1~ ~a The clinical picture of a papilloma of the fourth ventricle is one of increased intracranial pressure without localizing features except for ataxia, nystagmus, and cranial nerve palsies. ~,~,2~ In infants, the symptoms are those of progressive hydrocephalus with enlargement of the head, apathy, irritability, and a failure to thrive. In adults, the hydrocephalus is caused by obstruction to the circulation of cerebrospinal fluid, while in infants it frequently is due to the increased secretory surface created by the tumor which causes a concomitant increase in the production of cerebrospinal fluid.~, 9, ~ 6, ~7 Subarach-