A Case of Medulloepithelioma Originating from the Retina

Purpose: To report a rare case of medulloepithelioma originating from the retina. Case summary: A nine-year-old boy visited our clinic with conjunctival injection and decreased visual acuity in the left eye, which had developed two month previously. Slit lamp examination revealed a distorted pupil and an anteriorly protruding ciliary body displacing the peripheral iris toward the cornea on the inferonasal side. Funduscopic examination showed total retinal detachment accompanied by an inferior hypervascular mass. The examination of the right eye was unremarkable. On computer tomography imaging, a calcified mass was identified behind the iris of the left globe in the inferomedial aspect, and ultrasound biomicroscopy revealed a medium to high echogenic tumor with an uneven oval cystic cavity in the ciliary body. At the follow-up examination, the size of the mass was increased, so we performed enucleation of the left eye. Pathology demonstrated that the retrolental mass abutting the lens had arisen from the retina. Histological examination revealed that the tumor had originated from the retina and extended into the ciliary body, and most of the tumor was composed of hyaline cartilage with calicification. Tumor cells were identified in the periphery, forming elongated tubules and cord-like structures that were immunohistochemically positive for vimentin, neuron-specific enolase, and CD56 compatible with a teratoid medulloepithelioma. The patient was followed up for eight months without any metastasis in the orbit or elsewhere. Conclusions: Medulloepithelioma should be considered in the differential diagnosis of pediatric orbital mass accompanied by calcification.