Contributor: Gordon K. Klintworth
The medulloepithelioma is a rare pediatric tumor that usually arises from the primitive neuroectoderm. In the eye it most often occurs on the surface of the ciliary body and forms from the neuroectoderm that gives rise to the non-pigmented ciliary epithelium. Rarely it involves the optic nerve. The tumor is composed of cords and sheets of polarized neuroepithelial cells that form elongated tubules and cystic structures in an abundant loose mesenchymal stroma rich in hyaluronic acid (analogous to primary vitreous). Special types of medulloepithelioma are the teratoid medulloepithelioma, malignant medulloepithelioma [medulloepithelioma - malignant] and malignant teratoid medulloepithelioma [medulloepithelioma - malignant teratoid].