Case #8

CT

• Masslike area of hypoattenuation involving the dorsal pons and middle cerebellar peduncles with mass effect on the fourth ventricle
• Mucosal thickening and fluid in the bilateral sphenoid sinuses and posterior ethmoid air cells

MRI

• Masslike area of T2/FLAIR signal hyperintensity involving the pons, midbrain including the cerebral peduncles, left eccentric medulla, and left greater than right middle cerebellar peduncles
• Area of relative restricted diffusion in the ventral aspect of the pons
• The mass bulges into the prepontine cistern and at least partially encases the basilar artery
• Associated mass effect on the fourth ventricle without overt hydrocephalus
• No corresponding enhancement