Paracollicular Cyst with Choroid Plexus-Like Epithelium （Case Report）

　Paracollicular cysts have been described under such　titles as rupture of the cerebral ventricle^19）， ven—triculostrium^17），ventricular diverticlae^5）， arachnoid　cyst^{1）2）8）10）} and ependymal cyst^7）． This cystic lesion　may produce hydrocephalus by obstructing the third　ventricle or Sylvian aqueduct and cause a variety　of neurologic symptoms due to its effect on the　thalamus, quadrigeminal plate, cerebral peduncle and　cerebellum．

　Kruyff's classification^11）　of paracollicular plate cysts　on the basis of ventriculographic and pneumoen—cephalographic findings includes the following　　groups： 1． communicating cyst with ventricle； 2．　communicating cyst with subarachonoid space ； and　3． noncommunicating cyst． The most interesting　cases are of the third type because of the difficulty　in differentiating them from other space-occupying　lesions such as tumors． We present a large para—collicular cyst of this third type accompanied by　obstructive hydrocephalus．