Empty sella secondary to suprasellar colloid cyst of foregut (respiratory) origin. Case report.

An enlarged sella turcica was discovered in a 40-year-old man who had bitemporal headaches. A pneumoencephalograph revealed a third ventricular cyst, dilated lateral ventricles, and an empty sella. The colloid cyst was lined by foregut epithelium, probably originating in the respiratory tract, and dense connective tissue. This case is the first instance of an empty sella associated with a colloid cyst of the third ventricle. It is proposed that enlargement of the mass in the third ventricle caused increased pulsation pressure of the cerebrospinal fluid, and that in the presence of an incompetent diaphragma sellae the subarachnoid space expanded into the sella. The origin of third ventricle cysts is reconsidered. It is concluded that suprasellar colloid cysts may arise from endoderm, ectoderm, neuroepithelium, or a combination of these epithelia.