Enlarging Temporal Arachnoid Cyst Extending Inside the Sphenoid Sinus.

Background: Cerebral arachnoid cysts that eroded the skull base and extended into the paranasal sinus are very rare with only a few cases reported.

Case Description: A 71-year-old woman with history of headache for 4 years was evaluated because of an enlarging right temporal cystic lesion with evidence of resorption of the greater wing of the sphenoid bone and a fluid-filled sphenoid sinus. For 3 years, the cerebral cyst remained stable and minimally symptomatic.