Glioneuroma associated with colobomatous dysplasia of the anterior uvea and retina. A case simulating medulloepithelioma.

The left eye of an otherwise healthy child was enucleated at the age of 2 months because of an enlarging mass involving the temporal iris, ciliary body, and anterior retina. The initial histopathologic diagnosis was malignant medulloepithelioma with orbital extension. Closer study revealed a superotemporal chorioretinal and ciliary body coloboma; dysplasia of the adjacent retina; a glioneuromatous mass replacing the temporal ciliary body, chamber angle structures, and iris and extending through the sclera to involve the insertion of the lateral rectus muscle; neuroepithelial elements resembling medulloepithelioma; and abnormally developed iris pigment epithelium, and dilator and sphincter muscles. Immunohistochemistry demonstrated that the main mass consisted of neurons positive for neuron-specific enolase (NSE), synaptophysin and neurofilaments, and glial cells expressing vimentin, glial fibrillary acidic protein, and S-100 protein. The neuroepithelial elements reacted positively for cytokeratins and S-100 protein, in addition to NSE and vimentin, suggesting ciliary epithelial rather than embryonic retinal origin. The tumor was rediagnosed as glioneuroma, which in this case was part of a widespread colobomatous dysplasia of the anterior uvea and retina. The patient is alive without metastases or local recurrence 2 years following enucleation and subtotal removal of the lesion.