Medulloepithelioma is a rare ciliary body neoplasm usually presenting before the age of 10 years. It is an embryonal tumor derived from the inner layer of the optic cup. It is typically characterized as nonteratoid or teratoid. Nonteratoid tumors involve medullary epithelial cells only, while teratoid tumors contain skeletal muscle, brain elements or cartilage. Medulloepithelioma can show benign or malignant features. These tumors rarely metastasize but can spread locally and have a high recurrence rate within the eye if local resection is performed.
|Any child with unexplained neovascularization of the iris should be suspected of having an intraocular tumor, such as medulloepithelioma, until proven otherwise. |
The tumor typically presents as a nonpigmented mass in the ciliary body, usually gray or pink in color. There are often small, clear cysts within the tumor that can be imaged with anterior segment optical coherence tomography or ultrasound biomicroscopy. This feature is strongly suggestive of the diagnosis. Another frequent feature is ectopia lentis and a lens notch. Cataract can be present. Occasionally, there is a retrolental opacification, which is thought to represent a sheet of proliferating tumor cells on the face of the anterior vitreous. Areas of calcification may be observed on ultrasonography.
A review of prevalence and mechanisms of secondary intraocular pressure elevation in eyes with intraocular tumors revealed high pressure in 17 percent of eyes with retinoblastoma and nearly all eyes with medulloepithelioma. Secondary glaucoma is a consistent feature of medulloepithelioma, most related to iris neovascularization.
In one series of seven patients from the Wills Eye Ocular Oncology Service with medulloepithelioma, five had neovascular glaucoma and two had tube shunts placed prior to detection of the intraocular mass. Medulloepithelioma should be highly suspected in any child with unexplained iris neovascularization.
Histopathologic evaluation reveals poorly differentiated round cells with scant cytoplasm. These cells form ribbon-like structures demonstrating polarity and produce a mucinous substance forming cysts. Malignant characteristics include poorly differentiated cells resembling retinoblastoma cells, areas that resemble sarcoma, presence of mitotic activity and local invasion.
Treatment options primarily include local resection, plaque radiotherapy and enucleation. For tumors with a cyclitic membrane, free-floating cysts and a friable appearance, enucleation is recommended. For small tumors without the aforementioned characteristics, local resection can be attempted, with the understanding of the possibility of future recurrence. Plaque therapy is another conservative option, as performed in this case.
The recurrence rate following resection can be problematic. One explanation is that the sheet of proliferating tumor cells on the hyaloid face could be left behind during local resection. In a case series from the Wills Eye Ocular Oncology Service of 10 patients with medulloepithelioma, four were managed with primary enucleation and six with local resection. In the long term, five of six eventually came to enucleation for recurrence. The one patient that avoided enucleation did have a small recurrence that was controlled with cryotherapy.
In conclusion, any child with unexplained neovascularization of the iris should be suspected of having an intraocular tumor, such as medulloepithelioma, until proven otherwise. These patients should be thoroughly examined to rule out medulloepithelioma. REVIEW
The author would like to thank Carol L. Shields, MD, Wills Eye Institute Ocular Oncology Service, for her assistance with this case.
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