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Aneurysmal bone cyst of the sphenoid bone extending into the ethmoid sinus, nasal cavity and orbita in a child.

An aneurysmal bone cyst (ABC) typically involves the long bones of the extremities, thorax, pelvis, or vertebrae. Skull base involvement is rare. We describe the case of a 9-year-old girl with ABC of the skull base. The patient had presented with nasal obstruction and headache over a period of approximately 8 months. The patient had no history of trauma or surgery. Physical and neurological examination findings normal. Magnetic resonance imaging (MRI) showed a multicystic lesion arising from the sphenoid sinus and extending into ethmoid sinus, superior nasal cavity and medial walls of the orbit. The lesion contained thin internal septations that revealed high signal characteristics on all sequences. The lesion was resected via an extended frontal approach without any complications. Histological evaluation confirmed that the lesion was an ABC. The patient did not receive postoperative radiotherapy. No recurrence was observed after 22 months. ABC should be considered in the differential diagnosis of bone neoplasms in this region.