Asymptomatic and Symptomatic Colloid Cysts of the Third Ventricle

Colloid cyst of the third ventricle is a well known neuropathological entity with consistent anatomic locations and a characteristic epithelial appearance. The authors describe 14 cases of histologically verified colloid cysts and discuss the histological differences between these and other epithelium-lined cysts in the central nervous system. The study population comprised eight males and six females ranging in age from 28 to 82 years. Eight were autopsy cases (mean age, 67 years) in which the colloid cysts were found incidentally. None of these cysts obstructed the foramen of Monro. Their mean size was 9×8×8 mm and, without exception, they were located in the anterior roof of the third ventricle. Six of the patients were surgical cases and their mean age was 37 years. The reasons for hospitalization were paroxysmal headaches in three patients, two of whom exhibited deterioration of consciousness; sudden, severe headache and unconsciousness with no history of headache in two; and longstanding, mild dementia and gait disturbance mimicking normal pressure hydrocephalus in one. The cysts were lined by cuboidal to columnar epithelial cells. Among the operated cysts, cilia were found in four and goblet cells in two. Periodic acid-Schiffpositive cells were observed in all of the stained specimens. No histological differences were noted between symptomatic (operated) and asymptomatic (found at autopsy) cysts. The ciliated epithelium lining colloid cysts of the third ventricle is similar to that observed in Rathke's cleft cyst and some epithelial cysts found elsewhere in the central nervous system.