Female, 46 years old, history of thymoma resection, with giant arachnoid granulation versus venous lake seen on recent CT scan. An area of focal calvarial thinning in the right frontal bone is seen containing CSF signal fluid. The space is in fact contiguous with the adjacent CSF space. No concerning solid or nodular enhancement is demonstrated. This area demonstrates at most minimal peripheral enhancement.Elsewhere in the brain, no significant parenchymal edema or mass effect. No abnormal extra axial fluid collections are seen. Parenchymal enhancement is within normal limits.
An area of focal thinning of the right frontal bone shows imaging features most compatible with a large arachnoid granulation. 