label: Suprasellar arachnoid cyst
label_lc: suprasellar arachnoid cyst
description: "An arachnoid cyst that progressively enlarges from an abnormality in the membrane of Liliequist or in the interpeduncular cistern, and typically, expands from the prepontine space, displacing the floor of the third ventricle upwards, the pituitary stalk and optic chiasm upwards and forwards, and the mammillary bodies upwards and backwards."