OLIG2 and infection: Revealed multifocal demyelinating leukoencephalopathy. Luxol fast blue special stain showing loss of myelin in multiple well-circumscribed lesions magnification. CD163 immunostaining highlights macrophages within the demyelinating lesions. Sv40 ruled out the JC virus. There was no evidence of infection. Oligo2 and PDGFRα stain showed loss of oligodendrocyte cells.