Computed tomography in the diagnosis of a colloid cyst of the third ventricle

A 58-year-old woman came to our hospital on July 19, 1984, with slowly progressive mental retardation, urinary incontinence, and gait disturbance of about six months' duration. Computed tomography (CT) revealed a low-density cyst in the third ventricle, a remarkable dilatation of the lateral ventricles, and P.V.L. The cyst was partially removed, and the V-P-shunt procedure was done. Her neurological complaints were completely relieved. The histological diagnosis was a colloid cyst. Although a colloid cyst is a relatively rare brain tumor, recently reports of the CT diagnosis of colloid cysts have been increasing in number; most of the cases have, though, been an iso- or high-density mass in the third ventricle. We here report an interesting case of a colloid cyst which appeared as a low-density mass in the third ventricle on CT. The colloid cysts, especially findings in the literature regarding the CT findings and the relationship between the density and the contents of the cyst, are reviewed. (author)