Pseudotumoral demyelinating lesions: diagnostic approach and long-term outcome

Purpose of review To review the clinical findings, differential diagnosis, treatment and outcome of pseudotumoral demyelinating lesions including tumefactive demyelination and Balo's concentric sclerosis. Recent findings MRI findings, such as dynamic restricted diffusion changes at the edge of pseudotumoral lesions help to discriminate atypical demyelination from key differential diagnoses, and together with histopathological data, indicate that tissue hypoxia may be important aetiologically. CT-PET imaging can help to distinguish pseudotumoral lesions from high-grade tumours. Although most patients with pseudotumoral lesions have or later develop multiple sclerosis, a proportion will experience a monophasic course or be diagnosed with neuromyelitis optica spectrum disorders (NMOSD), myelin oligodendrocyte glycoprotein (MOG) antibody associated demyelination or acute disseminated encephalomyelitis (ADEM). Many patients with pseudotumoral demyelinating lesions have a favourable prognosis. Summary Not all patients with pseudotumoral lesions require a brain biopsy but close follow-up of biopsied and nonbiopsied lesions is indicated once a diagnosis is established. Testing for AQP4-IgG and MOG-IgG is recommended when a pseudotumoral demyelinating lesion is identified. In the absence of large, prospective studies, it seems reasonable that patients with pseudotumoral lesions who fulfil multiple sclerosis diagnostic criteria are treated with multiple sclerosis therapies.