Cystic meningioma simulating arachnoid cyst: report of an unusual case.

The purpose of this paper is to show an unusual case of meningioma simulating arachnoid cyst on CT scan and MRI, diagnosed in a 63-year-old woman evaluated for headache and vision disorders. The meningioma shown is predominantly cystic with a small mural nodule enhancing after gadolinium and exhibiting diffusion restriction. Cystic portion of the tumor is hypodense on CT, and evidences fluid signal intensity on T1- and T2-weighted MR imaging.