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Intraocular medulloepithelioma is a rare embryonal neoplasm, usually presenting in the first decade of life as a unilateral, cystic ciliary body mass arising from the non-pigmented ciliary epithelium. Histologically, medulloepithelioma is classified as non-teratoid (a pure proliferation of medullary epithelial cells) or teratoid (containing heteroplastic elements such as hyaline cartilage, skeletal muscle or neuroglial tissue).1,2 Either group can be subclassified as benign or malignant, the latter showing evidence of poor differentiation, increased mitotic activity, and local invasion with or without extraocular extension.2
We report the progressive echographic findings in a case of malignant intraocular medulloepithelioma. Echographic examination, by B-scan (10 MHz probe) and high resolution anterior segment scan (20 MHz probe), was performed during two examinations under anaesthesia (EUA), using the I3 system.
An 18 month old girl presented with a distorted pupil apparently following a fall downstairs some 4 weeks previously. Her right pupil was displaced inferotemporally, with a localised area of ectropion uveae and underlying segmental lens opacity.
An urgent EUA confirmed the clinical findings. The retina and ora serrata were normal on funduscopy but there was the vague suggestion of a subtle whitish pars plana abnormality inferotemporally. Visualisation of this area was however hampered by the lens opacity. B-scan was normal but high resolution scan showed an inferotemporal peripupillary iris cyst with irregular thickening of the peripheral iris. The ciliary body appeared normal but a triangular opacity of moderate reflectivity arose from the inferotemporal pars plana and extended along a thickened anterior hyaloid face (fig 1). In the absence of a definite mass the tissue changes were thought possibly to be secondary to trauma, perhaps of a penetrating nature. It was decided to manage her conservatively with an initial period of observation and occlusion therapy.
Unfortunately, she was lost to follow up and re-presented 4 months later with a right mature cataract. A repeat EUA was performed and B-scan now showed a partial posterior vitreous detachment with cellular vitreous. High resolution scan showed extensive increased irregular echoes of variable reflectivity extending from the pars plana to the ciliary body and along the anterior hyaloid face to the posterior lens. Small echolucent areas were present as well as one area of hyper-reflectivity inferotemporally. Although there was no absolute shadowing posterior to this hyper-reflective area, it remained highly reflective at low gain suggesting possible cartilage (fig 2A–C). Lens aspiration was performed revealing a dense, vascularised cyclitic membrane and underlying white fibrous tissue circumferentially around the pars plana and ciliary body though no distinct mass. Inferotemporally this structure was cystic with an area of hard chalky tissue, corresponding to the bright echo on scan, which was again thought probably to represent cartilage. A diagnosis of possible medulloepithelioma was made and confirmed on subsequent histological examination of tissue biopsies and vitreous cytology. Unfortunately, during surgery she developed an inferotemporal retinal dialysis requiring vitrectomy and inevitably some retrolenticular tissue was lost to further histological analysis during this procedure. Subsequent enucleation and extensive histological examination of the globe confirmed the diagnosis of malignant medulloepithelioma, although no heterologous elements could be identified in the available tissue.
Limited information exists regarding the echographic features of medulloepithelioma.1,3–5 We had the rare opportunity of examining a case of malignant medulloepithelioma by B-scan and high resolution scan at both early and later stages of development, showing significant progression of the condition. Our case presented with a pupil abnormality, localised segmental cataract and probable early cyclitic membrane arising from the pars plana but not with a typical ciliary body mass. Development of a cyclitic membrane is a recognised feature associated with medulloepithelioma.1,4–6 We have demonstrated the value of high resolution echography in such cases particularly demonstrating early changes when little was clinically evident. Our case demonstrates that, even in the absence of a ciliary body mass, the suggestion of early or unusual retrolental membrane should alert one to the possible diagnosis of intraocular medulloepithelioma.