Table 1 Core features and proposed diagnostic criteria for chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids

Clinical

 Subacute pontocerebellar dysfunction with or without other CNS symptoms such as cognitive dysfunction and myelopathy

 CNS symptoms responsive to corticosteroid therapy

 Absence of peripheral nervous system disease

 Lack of alternative explanation for clinical presentation

Radiological

 MRI with homogeneous, gadolinium-enhancing nodules without ring enhancement or mass effect predominating in the pons or cerebellum measuring < 3 mm

 Marked improvement in gadolinium enhancement after corticosteroid treatment

 Homogeneous T2 signal abnormality where degree of T2 does not significantly exceed the size or area of post gadolinium enhancement

 Spinal lesions with similar T2 and gadolinium-enhancing lesions as above

Pathological

 Lymphocytic inflammation with perivascular predominance and parenchymal diffuse infiltration

 T cells predominating infiltration with variable macrophage components

 Absence of myelin loss or focal secondary myelin loss

 Lack of alternative explanation for pathological presentation

Definite CLIPPERS: patient fulfilling all clinical, radiological, and pathological criteria

Probable CLIPPERS: patient fulfilling all clinical and radiological criteria without available pathology

Differential diagnoses, including CNS lymphoma, lymphomatoid granulomatosis, glioma, primary CNS vasculitis, paraneoplastic syndrome, neurosarcoidosis, demyelinating disease, acute disseminated encephalomyelitis (ADEM), neuromyelitis optica (NMO) neuro-Behcet’s disease, Sjögren’s syndrome, tuberculosis, Whipple’s disease, and histiocytosis, should be excluded