The Variable Appearance of Third Ventricular Colloid Cysts: Correlation with Histopathology and the Risk of Obstructive Ventriculomegaly

An overview of the imaging appearance of third ventricular colloid cyst on MR imaging.

Homogeneously hyperintense cyst: 13-year-old boy found unconscious after complaining of headache for 2 days. Initial CT demonstrates dilation of the lateral ventricles. However, the colloid cyst was difficult to detect as it was isointense relative to the adjacent brain. Subsequent MR imaging showed a colloid cyst homogeneously hyperintense on T2 (B) and T2-FLAIR weighted images (C) and hypointense on T1-weighted axial image (D). Also, note the presence of periventricular edema associated with ventriculomegaly.

Cyst with rim: 55-year-old woman with a 6-week history of headache. Non-contrast CT (A) shows a hyperattenuated colloid cyst measuring 13 mm at the roof of third ventricle. On T2WI (B), the colloid cyst has a hypointense core with a thin hyperintense rim, which is more pronounced on T2-FLAIR (C). The cyst is mildly heterogeneous and isointense centrally on T1-weighted image (D). There was no evidence of hemorrhage on the GRE sequence (image not shown). There is associated enlargement of the lateral ventricles with periventricular edema.

Hematoxylin and Eosin staining of a typical homogeneously hyperintense cyst on T2 and T2-FLAIR images. The cyst wall is composed of columnar, ciliated epithelial cells. The wall was not thickened and there was not an abnormal increase in goblet cells or any cellular atypia. Contents of the cysts consisted of a mucoid material with detached epithelial clusters of cells.