Meduloepitelioma pigmentado maligno intraocular. Presentación de dos casos Intraocular malignant pigmented medulloepithelioma. A report of two cases

SUMMARY Intraocular medulloepithelioma is a rare embryonal tumour that occurs most often in the ciliary body, but may also arise from the iris, retina or optic nerve. We present two cases of pigmented malignant intraocular medulloepithelioma; one teratoid (with hyaline cartilage as a heterologous element), and one non-teratoid. Histochemistry showed the neoplastic cells synthesizing both an acidic substance that stained positive with alcian blue and melanin pigment positive for FontanaMasson stain. Immunohistochemistry showed positive staining for markers of several lines of differentiation including neuroepithelial (S100 protein, synaptophysin), glial (GFAP), mesenchymal/muscle (vimentin, desmin), epithelial (cytokeratin AE1/3, EMA) and melanocytic (HMB-45, Melan-A). Intraocular medulloepithelioma is composed of multipotential cells capable of polyimmunophenotypic expression.