Intraocular Medulloepithelioma

Abstract

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.

Ocular glioneuroma with medulloepitheliomatous differentiation in a goldfish (Carassius auratus)

“…Under high magnification, the cords of the primitive neuroepithelium may display features of the developing neurosensory retina. When the medullary epithelium folds so that the vitreous surface faces inward, it creates Alcian blue-stained cyst-like dilations rich in hyaluronic acid 29 ; this feature was also present in the current case. In the present case, histological sections revealed some hypercellular areas with pseudostratified epithelium which helped to identify the tumor origin.…”

“…29 Vimentin is positive in the nonteratoid component, whereas limited and conflicting results have been reported for other markers like chromogranin, synaptophysin, GFAP, S100 protein, pancytokeratins, and cytokeratins 18, 7, 20, and epithelial membrane antigen. 29 In the present case, the positive results obtained for vimentin and GFAP are in accordance with the results reported in a human case, 14 and in domestic and nondomestic animal cases of medulloepithelioma. 5,30 The Hu proteins (especially HuD) are recognized as one of the earliest markers of the neuronal phenotype, 25 as such proteins suppress neuroblast proliferation and promote neuronal differentiation.…”

“…Areas rich in loose-extracellular matrix were interpreted as vitreous-like. 29 The external limiting membrane was identified with PAS stain. 21 Immunohistochemical markers of human medulloepithelioma have different reactivity patterns depending on whether the neoplasm is neuroepithelial or heteroplastic.…”

Intraocular Tumors

“…Even "benign" forms tend to continue to grow unless completely excised. Malignant medulloepitheliomas that are completely removed have a good prognosis, but once extraocular spread has taken place, local spread or metastatic disease may prove fatal [ 54 ]. An association between ciliary body medulloepithelioma and pleuropulmonary blastoma has been described [ 55 ].…”

Detection of Calcifications in Retinoblastoma Using Gradient-Echo MR Imaging Sequences: Comparative Study between In Vivo MR Imaging and Ex Vivo High-Resolution CT

“…2 Very rare lesions such as medulloepithelioma and retinocytoma may also have calcifications and hence occasionally cause difficulty with clinical and radiologic differentiation. 3 Sonography is the most commonly used imaging technique for the evaluation of intraocular tumors. The combination of funduscopy and sonography allows the identification of calcifications in 91%-95% of all patients with newly diagnosed retinoblastoma.…”