Disorder of brain, unspecified [G93.9], Reason for Study: ^Reason: eval post fossa mass History: ataxia Brain MRI:There is 40 x 38 x 38mm sized heterogenous signal intensity mass arising posterior superior aspect of the 4th ventricle. The infero- mesial aspect of the right cerebellar hemisphere shows high signal intensity on T2/FLAIR but showing minimal or equivocal enhancement, nor restricted diffusion. Thus, this could represent extension of the original mass which are non-enhancing part (the phenotype of the tumor could be different) or could represent compressed right PICA territory with subacute or chronic ischemic infarction. The mass shows mass effects against 4th ventricle which shows compressed from the posterior aspect and cerebellar tonsils appear to be pushed down through the foramen magnum. Post Gad enhanced images show heterogenous enhancement.Ventricular system appears to be enlarged with periventricular high signal intensities on periventricular white matter indicating interstitial edema in obstructive hydrocephalus.Constellation of above findings indicate possible medulloblastoma and the differential diagnosis include ependymoma.The paranasal sinuses and mastoid air cells are clear.Spine MRI:There is 4th ventricular mass with heterogenous enhancement with mass effects towards cerebellar tonsils creating downward herniation.There is normal thoracic kyphosis and lumbar lordosis. The spine alignment is anatomic. The vertebral body height is preserved. The bone marrow and end plates demonstrate a normal MR appearance. The cord signal is normal. The epidural space, thecal sac, and spinal cord are preserved with no evidence of spinal canal/neural foraminal stenosis, cord compression or myelopathy. The conus medullaris terminates at the level of T12-L1.The intervertebral discs demonstrate normal T2 intensity and height with no evidence of disc herniation. The paraspinal soft tissues and musculature are unremarkable.There is no evidence of abnormal enhancement.
1. 4th ventricular heterogeneous mass with heterogenous enhancement, possible diagnosis include medulloblastoma and ependymoma.2. Normal spine MRI