FIG. 2.

A: Right cerebellomedullary cistern. The cyst wall (white arrowhead) occupies the medial CPA cistern. The content resembles CSF. The white arrow indicates the choroid plexus; the black arrowhead indicates the lower cranial nerves. An AMR was detected. B: Dissection of the cyst wall. The AMR disappeared (white arrowhead) after cyst perforation. C: After resection of the cyst wall, the REZ of the facial nerve (black arrow) is exposed. No offending arteries are observed. D: Pathological photomicrograph (hematoxylin & eosin staining, original magnification ×20). The cyst wall has simple or stratified squamous epithelia compatible with arachnoid cysts.