Phenotyping variants of tumefactive demyelinating lesions according to clinical and radiological features-A case series.

Background: Tumefactive demyelinating lesions (TDLs) are defined as lesions >2 cm on MRI of the brain. They are identified in a range of demyelinating diseases including massive demyelination due to Marburg's acute MS, Schilder's Disease, Balo's concentric sclerosis, and Tumefactive MS. Apart from the rare demyelinating variants which are often diagnosed histologically, there are no detailed data to phenotype TDLs. Methods: We describe the clinical and radiological features of four similar patients with very large TDLs (>4 cm), that are not consistent with the rare demyelinating variants and may represent a distinct phenotype. Results: All patients presented with hemiplegia and apraxia. The mean age at onset was 37 years with an equal sex distribution. All patients were diagnosed with Tumefactive demyelination based on MRI and CSF analysis, precluding the need for brain biopsy. All responded to potent immunotherapy (including high dose corticosteroids, plasma exchange, rituximab, and/or cyclophosphamide). The mean lag from diagnosis to treatment was 1 day. The median EDSS at presentation was six and recovery to a median EDSS of two occurred over 6 months. Conclusion: We propose that Tumefactive lesions larger than 4 cm are termed "Giant demyelinating lesions" (GDLs) not only on the basis of size, but a rapid and fulminant demyelinating presentation leading to acute, severe neurological disability that is, nonetheless, responsive to immunotherapy. Further clinical studies are required to ratify this proposed phenotype, establish the immunological profile and best treatment for such patients.