A Familial Case of Spontaneous Regression of Colloid Cyst of the 3rd Ventricle on Magnetic Resonance Imaging

Abstract

A 21-year-old male underwent screening for a positive family history of colloid cyst with an MRI scan. This suggested a lesion in
the region of the roof of his 3rd ventricle which was confirmed on a computerized tomography (CT) scan as a colloid cyst measuring
6 mm. Seven-years before his evaluation, the patient’s father was found to have an approximately 20 mm colloid cyst with
acute hydrocephalus for which he underwent excision. His sister suffered a sudden death at the age of 25. The cause of death was
confirmed on autopsy as a colloid cyst which was undiagnosed and associated with acute hydrocephalus. At the time of evaluation,
the patient was asymptomatic. On serial imaging in 1-year, there was a definite increase in size of the colloid cyst which now
measured 8 mm along its maximum dimension. The colloid cyst also changed in signal intensity appearing more hyperintense on
T2-weighted images and fluid-attenuated inversion recovery (FLAIR) sequence. A serial magnetic resonance imaging (MRI) was
performed in 18-months as a part of ongoing surveillance with neuroimaging following the first presentation. This demonstrated
a decrease in size and change in the shape of the colloid cyst, measuring 5 mm in maximum dimension, with associated decrease
in ventricular size and resolution of hydrocephalus suggesting some spontaneous rupture of the colloid cyst. A CT head with
unenhanced volume acquisition of the head demonstrated residual partially international organization for standardization (ISO),
partially hyperdense colloid cyst seen at the foramen of Monro. This confirmed the findings of MRI with a decrease in size of
residual colloid cyst measuring approximately 5 mm in maximal diameter with no residual hydrocephalus.