they result in an increased risk of ms onset. solitary sclerosis normally a tumefactive demyelinating lesion appears together with smaller disseminated lesions. hence the name "tumefactive multiple sclerosis". when the demyelinating lesion appears alone it has been termed "solitary sclerosis" this variant was first proposed (2012) by mayo clinic researches. though it was also reported by other groups more or less at the same time. it is defined as isolated demyelinating lesions which produce a progressive myelopathy similar to primary progressive ms, and is currently considered inside the tumefactive multiple sclerosis. some groups have reported some kind of response of this variant to biotin solitary pontine lesion syndrome consisting in solitary lesions uniformly located along the trigeminal pontine pathway, producing trigeminal neuralgia (tn). they present similar clinical features than ms-tn but with a single pontine lesion. mog antibody‐associated demyelinating pseudotumor main article: anti-mog associated encephalomyelitis some anti-mog cases satisfy the ms requirements (lesions disseminated in time and space) and are therefore traditionally considered ms cases. after the discovery of the anti-mog disease this classification is into revision.