Brain MRI demonstrated an increased T2 signal at multiple sites in the brain parenchyma, such as the left cerebellar hemisphere, the brainstem, and the right thalamus, some of which were swollen and enhanced with gadolinium (Figures 1A-1F). No lesion was demonstrated in the cervical spinal cord MRI. Computed tomography (CT) scanning of the body did not reveal any massive lesions in the lung, the solid abdominal organs, or the lymph nodes. Malignant lymphoma, lymphomatoid granulomatosis (LYG), neurosarcoidosis, and neuroinflammatory response caused by an unidentified opportunistic infection were suspected.