Table 4.

Relevant differential diagnoses of CLIPPERS (chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids).

Disease entity	Diseases
Dominant inflammatory	Autoimmune encephalitis Seropositive autoimmune encephalitides (e.g. anti-NMDA receptor encephalitis, anti-GABAB receptor encephalitis, anti-AMPA-receptor encephalitis, anti-VGKC-complex antibody associated encephalitis, anti-GAD antibody associated encephalitis) Seronegative autoimmune encephalitides Bickerstaff brainstem encephalitis CNS vasculitis Primary CNS vasculitis (primary angiitis of the CNS: PACNS) CNS involvement in primary systemic vasculitis (e.g. microscopic polyangiitis, Wegener's granulomatosis with polyangiitis, Churg–Strauss syndrome, polyarteriitis nodosa) CNS vasculitis secondary to systemic connective tissue diseases (e.g. SLE, rheumatoid arthritis), infections (e.g. viral, bacterial, fungal, parasitic), malignancies (e.g. haematological, lymphoid) Inflammatory demyelinating diseases of the CNS Multiple sclerosis (MS) Acute disseminated encephalomyelitis (ADEM) Neuromyelitis optica (NMO), NMO spectrum disorders (NMOSD) Neuro-Behçet Neurosarcoidosis Sjögren's syndrome with CNS involvement Systemic lupus erythematosus (SLE) with CNS involvement
Infectious	Primary CNS infections
Paraneoplastic	Paraneoplastic diseases (e.g. paraneoplastic brainstem encephalitis/rhombencephalitis)
Dominant neoplastic (and/or clonal proliferative)	CNS histiocytosis including Langerhans cell histiocytosis and Erdheim–Chester disease CNS lymphoma Glioma Lymphomatoid granulomatosis Malignant histiocytosis with CNS involvement

CNS: central nervous system; AMPA: α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid; NMDA: N-methyl-D-aspartate; GABA: gamma-aminobutyric acid; GAD: glutamic acid decarboxylase; VGKC: voltage-gated potassium channel.