Non‐Neoplastic Lesions of the Ependyma: A Neuropathological Overview

Abstract

Non‐neoplastic lesions of the ependyma have been neglected to date in comparison with neoplastic lesions derived from the ependyma, that is, ependymoma. The ependyma has a simple structure: mono‐layered cuboidal cells covering the surface of the cerebral ventricles and the central canal of the spinal cord. In this review, the histopathological appearances of various non‐neoplastic ependymal lesions are shown based on the author's personal experience, along with a review of the relevant literature. Following the introductory remarks about the normal histology and functions of ependymal cells including tanycytes, non‐neoplastic lesions are then presented including, obliteration of the spinal central canal; the “ventriculus terminalis”; shedding of ependymal cells and “granular ependymitis”; “ependymal incorporation”; ependymal cells in hydrocephalus; ependymal reactions to various noxious stimuli; ependymal changes in cerebral dysgenesis; infections involving ependymal cells; glio‐ependymal cyst; and finally, various intracellular inclusions in ependymal cells. Non‐neoplastic ependymal lesions are intriguing and merit further investigations, which may provide deeper understanding of various brain lesions and of ependymal neoplasms.