DIZYGOTIC TWINS WITH A COLLOID CYST OF THE THIRD VENTRICLE

Abstract

Colloid cysts of the third ventricle are rare benign tumors of endodermal origin accounting for 1% of all intracranial tumors. Interestingly, a few familial cases have been reported previously. We present the first case of dizygotic twins with a symptomatic colloid cyst of the third ventricle. A 10-year-old boy was admitted to a local hospital in 1993 because of severe progressive headache. Computed tomographic and magnetic resonance imaging scans revealed acute obstructive hydrocephalus attributable to a third ventricular colloid cyst, which was removed after emergent ventricular drainage. Fourteen years later, a nonidentical twin brother complained of continuous headache with nausea and vomiting. A magnetic resonance imaging scan showed obstructive hydrocephalus and a third ventricle colloid cyst, which was removed by use of the transcallosal approach. Both twins underwent complete removal of the cyst by the interhemispheric transcallosal approach without postoperative complications. On the basis of a literature review, 2 cases of colloid cysts of the third ventricle in monozygotic twins and a few familial cases have been reported. Our case is the first in dizygotic twin brothers. These findings suggest that the prevalence of colloid cyst may be higher in twins than in the general population. We believe that the presence of this lesion in a twin necessitates magnetic resonance imaging of the other twin, and a clinical follow-up would be recommended in all other first-degree relatives.