Primary Ewing Sarcoma of Sphenoid Bone with Intracranial Extension: A Common Tumour at an Uncommon Location.

Primary Ewing Sarcoma of the cranial bone is rare, contributing to only 1% of all Ewing Sarcomas. Primary cranial Ewing Sarcoma occurs most commonly in temporal bone followed by parietal and occipital bones. Sphenoid bone is less commonly involved. We report a case of Ewing Sarcoma of the sphenoid bone with intra-cranial extension in a 20-month-old boy. On CT scan a provisional diagnosis of rhabdomyosarcoma was made. Fine Needle Aspiration Cytology (FNAC) and histopathological examination of core needle biopsy showed small round cell tumour. On Immunohistochemistry (IHC), CD99 (MIC2) and FLI 1 were strongly positive and final diagnosis of Ewing Sarcoma was made. Considering the rarity of this unusual site, we report a case of primary Ewing Sarcoma arising in the sphenoid bone with erosion of adjacent bones and intra-cranial extension.