History:A34-year-oldmanwithHIVpresentswithconfusionandgaitdifficultyforthepastweek.
简要病史：34岁HIV患者，出现意识混乱和步态困难一周。
Findings
CT:Thereisahyperdensemasscenteredintheperiventricularrightfrontallobe,exertingmasseffectonthefrontalhornoftherightlateralventricleandthirdventricleandlikelyobstructingtheforamenofMonro.Thereissurroundinghypoattenuation,likelyreflecting,inpart,moderatevasogenicedema.Thereisassociatedthickeningoftheseptumpellucidum,likelyreflectingneoplasticinvolvement.Thereisresultantmoderatedilationofthelateralventricles,reflectinghydrocephalusandmildleftwardmidlineshift.
MRI:Anill-definedmasscenteredintherightperiventricularwhitematterwithdominantenhancing