GLIOMA-11 JUVENILE OLIGODENDROGLIOMA OF THE OPTIC NERVE: UNIQUE CASE REPORT AND CHALLENGE IN DIAGNOSIS ACCORDING TO CURRENT 2021 WHO CLASSIFICATION IN LIMITED RESOURCES COUNTRIES.

BACKGROUND: The list of most commonly occurring primary brain tumors includes gliomas, and the vast majority of these are astrocytomas or oligodendrogliomas. Oligodendrogliomas, account for about 3% of all intracranial tumors and 20% of gliomas. They are more commonly found in adults and occur mainly in the superficial gray matter of the cerebral hemispheres. For this tumor, 69% of the lesion is located in the frontal lobes. Involvement of the hypothalamus and optic chiasm are rarely seen and the tumor is most rare within the eye itself. The positive stain of IHC stain GFAP and OLIGO-2 overexpression is required for confirmation of diagnosis. Molecular genetics study of IDH-mutant is used for WHO grading and management of the oligodendrogliomas lesions. CASE PRESENTATION: A 10 years old male presented with progressive blurred vision for 2 years and left eye globe protrusion for 1 month. On examination, he present with keratopathy, loss of vision, and pus discharge on the left eye. The Brain MRI was done and showed a left orbital heterogeneous enhancing lesion with mixed cystic and soft tissue involving both the globe and retrobulbar region with associated distortion of the optic nerve. The eye globe enucleation was done and tissue samples were taken for histopathology. The histopathology diagnosis reveals the optic nerve oligodendroglioma (NOS). The patient was kept on 8 cycles of Carboplatin chemotherapy. CONCLUSION: Definitive diagnosis of Juvenile Oligodendroglioma of the optic nerve can be made only after the results of pathological and immunohistochemical analyses are known. Also, the current WHO grading of Oligodendroglioma requires molecular genetics IDH study. Although Juvenile Oligodendroglioma of the optic nerve is extremely rare, preoperatively oligodendroglioma should be included in the differential diagnosis of optic nerve tumors in pediatrics especially in limited settings with no molecular IDH testing.