COLLOID CYST OF THE THIRD VENTRICLE COLLOID CYST OF THE THIRD VENTRICLE ASSOCIATED WITH CONGENITAL CYSTIC KIDNEYS * BY.

WHILE true neoplasms in the region of the third ventricle are of fairly common occurrence, colloid cysts within its cavity are somewhat infrequently met with. The first two cases in this country were published by Batten and Collier (1899) and Mott and Barratt (1899); these were followed by Kinnier Wilson's case in 1906. The first series of cases was collected by Hall (1913), who found seven cases in the literature and added two of his own. Twenty years later, Zimmerman and German (1933) reviewed all the recorded cases, 28 in number, and added two more, one of which was successfully operated on. Dandy (1934), in his recent book on benign tumours of this area, records operations on five cases of colloid cyst. The cyst wall was removed completely in all and there was only one fatality-a month after the operation-due to blocking of the aqueduct of Sylvius. Cysts in this region are not always of choroid plexus or ependymal origin. In a number of reported cases they have been epidermoid or parasitic in nature; others are stated to be derived from the hypophysis. One case was considered by the author to be a degenerate