MR imaging in aneurysmal bone cyst of the orbit.

Aneurysmal bone cyst is a benign fibro-osseous lesion usually described in the long bones. Intraorbital aneurysmal bone cyst is a rare clinical entity with an entirely different outcome and prognosis as compared to the usual pediatric orbital tumors. The authors report magnetic resonance imaging (MRI) features of an orbital mass lesion in a 4-year-old child who presented with painless proptosis of right eye. Characteristic MRI findings led to a suspicion of an aneurysmal bone cyst that was totally excised via a right frontotemporal craniotomy. Appreciation of characteristic MRI features can be of extreme help for appropriate diagnosis and management of this rare entity.