Familial colloid cyst of the third ventricle.

We describe the cases of a mother and son who presented one year apart with a colloid cyst of the third ventricle. The mother was symptomatic and had complete resolution of her symptoms after surgical intervention. Her son was asymptomatic. There have been several reported instances of a familial association of colloid cysts of the third ventricle. The probability of a colloid cyst occurring in the same family coincidentally is possible, but highly unlikely (1 x 10(10)). The increasing number of reports of the familial incidence of colloid cysts would suggest the possibility of an autosomal dominant inheritance pattern, but to date, a familial pattern of inheritance has not been recognised. If there is a potential genetic link, then screening of asymptomatic relatives may be indicated. With non-invasive imaging techniques, such as computed tomography and magnetic resonance imaging scanning, accurate diagnosis and effective elective treatment is possible. This may result in preventing future complications as a result of hydrocephalus or sudden unexpected death, and also reduce morbidity as surgery can be done electively rather than as an emergency procedure.