Tumefactive multiple sclerosis is a term used to describe patients with established multiple sclerosis who develop large aggressive demyelinating lesions, similar/identical in appearance to those seen in sporadic tumefactive demyelinating lesions (TDL). TDL is now considered to be a separate entity, lying on a spectrum between multiple sclerosis and postinfectious demyelination/acute disseminated encephalomyelitis (ADEM) 1-3.
This appears at first to be an unnecessarily complicated and pedantic distinction, however, this is potentially important as patients who present with a tumefactive demyelinating lesion do not usually progress to multiple sclerosis 1-2. Additionally, there may be histopathological differences between a TDL and tumefactive multiple sclerosis plaques, namely the presence of more pronounced axonal damage in the latter 1.
When reading about demyelination, one must be wary of older publications that do not draw a distinction between multiple sclerosis with larger tumefactive-like lesions and what is now considered true tumefactive demyelinating lesions.
Differential diagnosis
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there is a concentric ring pattern