Findings:
Since the last examination, a right frontal approach EVD catheter has been placed. The tip is in the anterior horn of the right ventricle. There is slight interval decompression of the ventricular system. There is still persistent transependymal fluid migration.

There is again a predominantly cystic mass within the posterior fossa which effaces the fourth ventricle and the caudal aspect of the cerebral aqueduct. The cyst does not contain high amounts of proteinaceous material as there is no diffusion restriction or increased signal on FLAIR imaging. IV contrast administration leads to enhancement of the mural nodule along the left superior lateral margin. The maximal transverse dimension of the enhancing nodule is approximately 38mm. The cyst produces mass effect within the posterior fossa resulting in downward tonsillar herniation and upward transtentorial herniation with complete obliteration of the superior cerebellar cisterns.

There is a punctate focus of blood product in the anterior left temporal lobe, likely along the anterior temporal horn of the right lateral ventricle.

Impression:
There is a 38mm cystic lesion with a 9mm enhancing mural nodule within the posterior fossa. This is most consistent with a hemangioblastoma. The mass produces an obstructive hydrocephalus at the level of the cerebral aqueduct and fourth ventricle with associated transependymal fluid migration. The cystic mass produces upward transtentorial herniation and downward tonsillar herniation.
A right frontal EVD was placed since the CT earlier today.

Recommendations:
For your training purposes, recommendations are not included in this report.