Computed tomography in the diagnosis of colloid cysts of the third ventricle

The computed tomographic findings in 14 cases of colloid cysts of the third ventricle are discussed. These tumors usually present as homogeneous, rounded lesions at the level of the foramina of Monro, with widening of the septum pellucidum. They are commonly hyperdense and show some enhancement upon injection of contrast material. The differential diagnosis of these tumors includes aneurysms of the tip of the basilar artery and the various gliomas of the third ventricle.