Oligodendrogliomas generally remain confined to the nervous parenchyma throughout their entire course. However, there are exceptionally rare cases, which show either transdural extension or extraneural spread. In reviewing the world literature on suchspread from oligodendrogliomas, very few cases were found, and the exit door from the CNS was almost always through the cranial base, anentitity termed as metastatic anaplastic oligodendrioglioma. Here we present one such rare case of a frontotemporal oligodendroglioma (WHO grade 3) with primary orbito-ethmoidal invasion. Patient presented with right sided proptosis and nasal cavity mass lesion causing epistaxis post. MRI revealedtransduralextension of tumor with right orbital and nasal cavity infiltration through the ethmoidal bone. Atransnasal endoscopic excision of the nasal mass conformed to the immunocytogenetics of an oligodendroglioma. The reporting of such cases is important because firstly following the advent of IHC and the new WHO 2016 classification, the lines between low and high grade gliomas have become blurred. Secondly, the pathogenesis underlying the invasion of neuroepithelial tumors outside the dural structures calls for further research and may promote anti-invasive therapy in the future.

Keywords: Oligodendroglioma; Extraneural; Orbitoethmoidal; Immunohistochemistry.