Arising from the right side of the midbrain is a mass which is mixed solid cystic. The solid component, which has smaller cysts embedded within it and is associated with a cyst around its posterior superior aspect.
The cystic component can be seen to displace the pineal gland superiorly, which is distinct from mass, and the tectal plate which is displaced posterosuperiorly. The mass is clearly extraventricular with the third ventricle displaced towards the left. The aqueduct is obstructed with established obstructive hydrocephalus and transependymal oedema.
The mass demonstrates no calcification intermediate ADC values and no evidence of haemorrhage. No abnormal flow voids. Cerebral blood volume is elevated in the enhancing component (not shown). MR spectroscopy demonstrates increased minor increased choline but is generally non-contributory (not shown).
Partially solid/cystic mass arising from the right side of the midbrain. By far the most likely diagnosis is that of a pilocytic astrocytoma/pilomyxoid astrocytoma.