A50-year-oldmanpresentedwithheadacheandcognitivedecline10weeksafterundergoingmatched-donorperipheralbloodstemcelltransplantationfortreatmentofmixed-phenotypeacuteleukemia.Hispretransplanttreatmentincludedsystemicchemo-therapy(cyclophosphamide,daunorubicin,vincristine,prednisone,L-asparaginase,dasatinib,andcytarabine),intrathecalchemotherapy(methotrexate),andtotalbodyirradiation.Hisposttransplantcoursehadbeen