What is the most likely histology in this patient?
Known NF1, with large peripherally enhancing left cerebellar cystic mass, vividly enhancing mural nodule, peripheral diffusion restriction, relatively mild surrounding oedema and mass effect resulting in mild to moderate hydrocephalus. These findings are strongly suggestive of pilocytic astrocytoma, with higher grade tumour not excluded.
Irregularly-shaped cystic mass within the left cerebellar hemisphere demonstrates homogeneous T1 signal, high T2 signal and sharply delimited rim enhancement with a vividly enhancing superior nodule. The mass exerts positive mass effect upon the fourth ventricle, displaced to the right, with evidence of ambient cistern effacement mild symmetrical temporal horn dilatation in keeping with mild hydrocephalus. The mass is separate from the left tentorium cerebelli.
There is associated mild diffusion restriction with ADC depression (not shown) in the periphery of the lesion. No additional intracranial lesion is seen. Minimal surrounding edematous change.
Screening T2 sagittal images of the whole spine were obtained, with no evidence of mass lesion and normal cord signal. Capacious spinal canal. (not shown).