Fig 3. A, B, Coronal high-resolution bone window CT image (A) depicts a small erosion of the inferolateral recess (arrow) in a 70-year-old woman (patient 18) with massive intermittent CSF rhinorrhea for 7 months. The coronal T2-weighted MR image (B) shows a fluid level within the left sphenoid sinus, air within ventricles, and an air bubble below the left inferior temporal gyrus. Adjacent subcortical gliotic changes are present. A lesion with soft tissue isointense components and CSF is shown (long arrow), which corresponded to endoscopy, and histologic examination proved the presence of arachnoid tissue.