GFAP and sarcoidosis: LETM can have various autoimmune, inflammatory, or infectious causes; the differential diagnosis comprises myelin oligodendrocyte glycoprotein antibody–associated disease (MOGAD), ADEM, glial fibrillary acidic protein (GFAP) astrocytopathy, multiple sclerosis, systemic lupus erythematosus, sarcoidosis, Sjögren's disease, Behçet's disease, infections (syphilis, herpes viruses, SARS-CoV-2, human immunodeficiency virus (HIV), Borrelia, Mycobacterium tuberculosis, Mycoplasma pneumoniae, and Streptococcus pneumoniae), and paraneoplastic, postinfectious, and postvaccination myelitis [4, 5].