Malignant teratoid medulloepithelioma is an extremely rare tumor occurring in children younger than 5 years of age, arising from ciliary body epithelium or iris but few arise from optic nerve and retina. This report concerns a 5 years old boy who presented with pain, redness and protrusion of right eye. Histopathologically, the tumor was composed of epithelial and sarcomatoid component. The pseudostratified primitive appearing epithelial cells were arranged mainly in diffuse pattern, nests

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... and tubules. At places, pseudo rosette and true rosette were seen. Mitoses were frequent consisting of 7-10/ HPF. The sarcomatoid component consisting of spindle shaped cells arranged in interlacing bundle were also seen. Mitoses counted 5-7/HPF. Massive areas of necrosis and hemorrhage along with calcification, focal area of mature cartilage were present. Vascular and optic nerve invasions were seen. This case of malignant teratoid medulloepithelioma is the second case diagnosed in TU Teaching Hospital within the period of 10 years and reported because of its rarity. The differentiations from other tumors of the orbit such as small cell tumor were discussed.