Tumefactive demyelinating lesions: A comprehensive review.

Tumefactive multiple sclerosis or tumefactive demyelinating lesion (TDL) is one of the rare variants of multiple sclerosis (MS) posing a diagnostic challenge and a therapeutic enigma since it is difficult to distinguish from a true central nervous system (CNS) neoplasm or other CNS lesions on magnetic resonance imaging (MRI). The prevalence of TDL is estimated to be 1-3/1000 cases of MS with an annual incidence of 0.3/100,000. This could be an underestimate due to unavailability of a global MS registry and under-reporting of this condition. TDL may occur at any age with the ages between the 20s and 30s being more frequently affected. The pathogenesis of TDL remains unknown, but some speculations have been made. These include the autoimmune theory based on the close relationship between TDLs and MS, Fingolimod use, Fingolimod cessation, and Natalizumab use. The clinical presentation of patients with TDL is variable and atypical for demyelinating disease due to the differences in size and location of the lesion. In this article, we aim to explore TDL comprehensively and provide an evidence-based approach for diagnosis and treatment. This will result in recommendations that may improve the diagnostic accuracy and treatment outcomes. Detailed history, physical examination, and several MRI imaging can spare patients the need for a brain biopsy. Treatment of acute lesions includes corticosteroids and plasma exchange therapy. When a diagnosis of relapsing-remitting MS is fulfilled, conventional first line MS disease modifying therapy should be used. Available recently published data suggests that Fingolimod should not be used in TDL patients, mainly due to the possibility of more than just a chance association between TDLs and initiation of Fingolimod. The use of several new MS disease modifying therapy for the management of TDL remains to be studied. Further well-conducted research including multi-center trials is needed to explain several ambiguous aspects related to the etiology and management of TDL.