Case #11

CT

• Ill-defined hyperattenuating mass in the superior aspect of the right cerebellar hemisphere
• Surrounding parenchymal edema
• Corresponding mass effect with crowding of the fourth ventricle and displacement of the cerebellar tonsils 13 mm below the foramen magnum
• Likely mild corresponding obstructive hydrocephalus

MRI

• Ill-defined T2/FLAIR hyperintense mass in the superior aspect of the right cerebellar hemisphere and superior aspect of the vermis measuring approximately 4.3 x 2.2 x 4.2 cm
• Nodular internal areas of restricted diffusion and corresponding patchy enhancement
• Peripheral susceptibility artifact about one of these nodular areas in the anterior aspect of the right cerebellar hemisphere, likely relating to hemorrhage
• Thickening and enhancement of the adjacent tentorial leaflet
• FLAIR signal hyperintensity in a right occipital sulcus and possible adjacent cortical FLAIR signal hyperintensity without definite corresponding restricted diffusion or enhancement (possibly representing leptomeningeal spread)
• Small focus of restricted diffusion along the falx without definite corresponding enhancement (also possibly a leptomeningeal tumor deposit)
• Associated mass effect in the posterior fossa resulting in cerebellar tonsillar herniation and crowding of the fourth ventricle with mild obstructive hydrocephalus