Case report of unilateral axial proptosis due to Aneurysmal bone cyst.

Aneurysmal bone cyst is rare condition presenting with proptosis. A 2 years old child presented with a gradual, progressive painless protrusion of left eyeball since 15 days & bleeding from left nasal cavity. On examination the proptosis was non pulsatile and non tender. Patient was uncooperative for visual acuity, anterior segment was normal, and a mass found in the left nasal cavity. Ultrasound of left eye showed a retro orbital mass of size 16x14 mm. MRI brain with orbit showed a cystic lesion around left superior & middle ethmoidal sinus 25x26x35mm, with post contrast thick peripheral enhancement and mild compression of intracranial optic nerve. ENT surgeon performed Functional endoscopic sinus surgery (FESS) which revealed a left side nasal cavity mass with diseased tissue from maxillary ostium, periorbital tissue, prolapsed dura and from supra orbital region left side sphenoid ostium, that was removed, and sent for histological examination. Anterior and posterior ethmoidectomy was done. The proptosis due to aneurysmal bone cyst of ethmoid bone was confirmed by histopathology.