Intraocular medulloepithelioma.

Intraocular medulloepithelioma is a congenital tumor of the ciliary epithelium that typically presents during the first decade of life. The histologic diagnosis is based on characteristic ribbons of pseudostratified neuroepithelium admixed with loose mesenchymal tissue rich in hyaluronic acid, vaguely resembling developing retina and vitreous. More than a third of medulloepitheliomas contain heteroplastic tissue, which in some cases makes up most of the tumor. Malignant medulloepitheliomas consist of a proliferation of neuroblasts, which in areas can be indistinguishable from retinoblastoma. Unlike its highly malignant counterpart in the central nervous system, intraocular medulloepithelioma has a good prognosis as long as tumor has not spread beyond the eye. Definitive diagnosis and eye-conserving therapy is possible with fine-needle aspiration biopsy. The histologic differential diagnosis of medulloepithelioma is broad, ranging from retinoblastoma and sarcoma to ciliary epithelial adenoma and adenocarcinoma.