41-year-old man with history of headache and incidentally noted cerebellar tonsillar lesion. There is a T2 hyperintense, T1 isointense, heterogeneously enhancing lesion with scattered foci of susceptibility artifact corresponding to calcification in the vermis and inferior fourth ventricle, which measures up to 31 mm. This lesion displaces the medulla anteriorly and extends inferiorly through the foramen magnum. The ventricles and basal cisterns are otherwise normal in size and configuration. There is no evidence of intracranial hemorrhage or acute infarct. There are minimal nonspecific foci of cerebral white matter T2 hyperintensity bilaterally, which may represent prominent perivascular spaces. There is no midline shift or herniation. The major cerebral flow voids are intact. The orbits, skull, paranasal sinuses, and scalp soft tissues are grossly unremarkable.
A heterogeneously enhancing and partly calcified lesion in the inferior vermis and fourth ventricle measuring up to 31 mm likely represents a subependymoma, without evidence of hydrocephalus.I personally reviewed the Images and/or procedure with the Resident/Fellow and agree with this report.