Microphthalmos with colobomatous orbital cyst: clinical, histological, immunohistological, and electronmicroscopic findings.

A case of unilateral microphthalmos with orbital cyst is presented. This rare and severe malformation is a non-hereditary disorder. Pathologically it represents a failure in the closure of the embryonic fissure at the 7-14 mm stage of gestation. Staining for neurofilaments permitted the identification of rudimentary optic nerve fibers within the gliomatous cyst wall. Special stains for glial fibrillary acidic protein as well as scanning and transmission electron microscopy were used to characterise the neuroglial cell lining of the cyst wall, and to show microvilli on its inner surface.