Presentation
Chronic headache.
Patient Data
Right anterior parietal well defined, thin-walled, oval-shaped, extra-axial CSF density cystic lesion measuring 3.3 x 2.5 cm, with remodeling effect on the adjacent bone, it is splaying the overlying inner table of the skull. It exerts a mild mass effect in the form of compression upon the underlying brain parenchyma, no midline shift. No associated edema at the related brain parenchyma.
Case Discussion
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.