Where is the abnormality?
Anterior to the third ventricle is a small, round hyperdense mass.
Colloid cysts are typically hyperdense but can have a variety of appearances. Why?
They contain mucin, old blood (haemosiderin), cholesterol, and various ions, accounting for the wide range of imaging appearance.
Where do they arise from?
Colloid cysts originate from abnormal folding of the primitive neuro-epithelium (the paraphysis elements).
No intra- or extra-axial collection or haemorrhage demonstrated. Hyperdense focus demonstrated anterior to the third ventricle consistent with a colloid cyst. Ventricular size is unchanged with no evidence of hydrocephalus.