Intraocular medulloepithelioma – A review of clinical features, DICER 1 mutation, and management

Intraocular medulloepithelioma is a nonhereditary neoplasm of childhood arising from primitive medullary epithelium. It most often involves the ciliary body. Most patients present between 2 and 10 years of age with loss of vision, pain, leucocoria, or conjunctival congestion. The mass appears as a grey-white ciliary body lesion with intratumoral cysts. Presence of a neoplastic cyclitic membrane with extension to retrolental region is characteristic. Secondary manifestations like cataract and neovascular glaucoma may be present in up to 50% and 60% patients, respectively. These could be the first signs for which, unfortunately, about 50% patients undergo surgery before recognition of the hidden tumor. Systemic correlation with pleuropulmonary blastoma (DICER1 gene) has been documented in 5% cases. Histopathology shows primitive neuroepithelial cells arranged as cords closely resembling the primitive retina. Histopathologically, the tumor is classified as teratoid (containing heteroplastic elements) and nonteratoid (containing medullary epithelial elements), each of which are further subclassified as benign or malignant. Retinoblastoma-like and sarcoma-like areas may be seen within the tissue. The treatment modality depends on tumor size and extent of invasion. For small localized tumors (≤3-4 clock hours), conservative treatments with cryotherapy, plaque radiotherapy, or partial lamellar sclerouvectomy (PLSU) have been used. Plaque brachytherapy is generally preferred for best tumor control. Advanced and extensive tumors require enucleation. Rare use of intra-arterial and intravitreal chemotherapy has been employed. Systemic prognosis is favorable, but those with extraocular extension and orbital involvement show risk for local recurrence and metastatic disease, which can lead to death.