Arachnoid cysts are asymptomatic benign lesions. They are usually located within the subarachnoid space and contain CSF. On imaging, they are characterized as well-circumscribed thin-walled cysts, displacing adjacent structures and following the CSF pattern (hypodense on CT and hyperintense on T2 with FLAIR suppression on MRI). They can also have a remodeling effect on the adjacent bone.