CD4 and graft versus host disease: Previous cases with biopsy results revealed CD3, CD4, and CD8 T cells infiltration of perivascular areas.[6] An experimental mouse model demonstrated parenchymal lymphocytic inflammation, microglia activation, and mild cerebral angiitis after allo-HSCT.[9] Therefore, inflammatory cells infiltration owing to chronic GVHD may promote arterial remodeling and pathological characteristics could be crucial for the diagnose of cerebral vasculitis.[5,10] Unfortunately, the patient's biopsy was not performed.