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Tumefactive multiple sclerosis is a condition in which the central nervous system of a person has multiple demyelinating lesions with atypical characteristics for those of standard multiple sclerosis (MS). It is called tumefactive as the lesions are "tumor-like" and they mimic tumors clinically, radiologically and sometimes pathologically.〔Xia, L., Lin, S., Wang, Z., Li, S., Xu, L., Wu, J., Hao, S. and Gao, C. Tumefactive demyelinating lesions: nine cases and a review of the literature. ''Neurosurg Rev'' 32:171-179 (2009).〕 These atypical lesion characteristics include a large intracranial lesion of size greater than 2.0 cm with a mass effect, edema and an open ring enhancement. A mass effect is the effect of a mass on its surroundings, for example, exerting pressure on the surrounding brain matter. Edema is the build-up of fluid within the brain tissue. Usually, the ring enhancement is directed toward the cortical surface.〔Kaeser, M. A., Scali, F., Lanzisera, F. P., Bub, G. A., and Kettner, N. W. Tumefactive multiple sclerosis: an uncommon diagnostic challenge. ''Journal of Chiropractic Medicine'' 10:29-35 (2011).〕 The tumefactive lesion may mimic a malignant glioma or cerebral abscess causing complications during the diagnosis of tumefactive MS. T2-hypointense rim and incomplete ring enhancement of the lesions on post-gadolinium T1- weighted imaging on brain MRI enable accurate diagnosis of TDL〔Kilic AK, Kurne AT, Oguz KK, Soylemezoglu F, Karabudak R., Mass lesions in the brain: tumor or multiple sclerosis? Clinical and imaging characteristics and course from a single reference center, Turk Neurosurg. 2013;23(6):728-35. doi: 10.5137/1019-5149.JTN.7690-12.3. PMID 24310455〕 Normally a tumefactive demyelinating lesion appears together with smaller disseminated lesions separated in time and space, yielding a diagnosis of Multiple Sclerosis. Hence the name "tumefactive multiple sclerosis". When the demyelinating lesion appears alone it has been termed solitary sclerosis.These cases belong to a multiple sclerosis borderline and there is not an universal agreement about how should them be considered. Tumefactive multiple sclerosis is a demyelinating and inflammatory disease. Myelination of the axons are highly important for signalling as this improves the speed of conduction of action potentials from one axon to the next. This is done through the formation of high-resistance, low-conductance myelin sheaths around the axons by specific cells called oligodendrocytes. As such, the demyelination process affects the communication between neurons and this consequently affects the neural pathways they control. Depending on where the demyelination takes place and its severity, patients with tumefactive MS have different clinical symptoms.〔Moore, G. R. W., and Esiri, M. M. The pathology of multiple sclerosis and related disorders. ''Diagnostic Histopathology'' 17(5):225-231.〕 == Pathology and causes == The pathology of the demyelinating lesion is heterogeneous. In acute phase, the plaques of lesions were characterized by massive demyelination with relatively axonal preservation associated with prominent reactive astrocytosis and profound infiltrates of macrophages.In plaques of chronic lesions, demyelinated lesions with relative axonal preservation and sharply defined margins were major findings. And myelin-laden macrophages accumulated at the edges of plaques and stayed relatively inactive with densely gliotic center and processbearing astrocytosis.〔Sun C, Liu J, Gui Q, Lu D, Qi X. Analysis of pathological characteristics of acute and chronic cerebral tumefactive demyelinating lesions. Zhonghua yi xue za zhi, 2014, 94(45):3557-3561. PMID 25622833〕 There are several conditions can produce tumefactive lesions. This is known because in some special cases the etiology can be identified. For example, there are some cases of NMO, misidentified as MS and treated with interferon-beta by mistake. Some of these patients developed tumefactive lesions.〔Harmel J, Ringelstein M, Ingwersen J, Mathys C, Goebels N, Hartung HP, Jarius S, Aktas O. Interferon-β-related tumefactive brain lesion in a Caucasian patient with neuromyelitis optica and clinical stabilization with tocilizumab. BMC Neurol. 2014 Dec 17;14(1):247. doi: 10.1186/s12883-014-0247-3. PMID 25516429〕〔Roberto Bomprezzi and J. Michael Powers, IFNβ-1b may severely exacerbate Japanese opticspinal MS in neuromyelitis optica spectrum: Japanese optic-spinal MS: Is it MS or neuromyelitis optica and does the answer dictate treatment? Neurology July 12, 2011 vol. 77 no. 2 195-196 doi: 10.1212/WNL.0b013e318219dde5〕 Anyway, it is important to have into account that NMO itself can also produce them〔Kazuo Fujihara, MD and Tatsuro Misu, AQP4 in biopsied demyelinating lesions as a diagnostic clue to NMOSD and MS, Neurology January 13, 2015 vol. 84 no. 2 110-111, doi: 10.1212/WNL.0000000000001135〕 Some other cases have been found related to viral infection,〔Dr. Rahul Handa. Tumefactive demyelination: A rare presentation of HIV. Annals of tropical medicine and public health. Vol 7. Issue 4. Jul. 2014 ()〕 some others related to NMOSD,〔Ken Ikeda et al. Repeated Non-enhancing Tumefactive Lesions in a Patient with a Neuromyelitis Optica Spectrum Disorder. Internal Medicine Vol. 50 (2011) No. 9 P 1061-1064, 2011/05/01, http://doi.org/10.2169/internalmedicine.50.4295〕 others could be paraneoplastic,.〔Jack R Broadfoot, Paraneoplastic tumefactive demyelination with underlying combined germ cell cancer, Pract Neurol doi:10.1136/practneurol-2015-001146, Neurological rarities 〕 Also some cases could be related to hormonal treatments〔Vaknin-Dembinsky et al. Tumefactive demyelination following in vitro fertilization (IVF). J Neurol Sci. 2015 Jan 15;348(1-2):256-8. doi: 10.1016/j.jns.2014.11.016. Epub 2014 Nov 18. PMID 25499758〕 Other possible cause are immunomodulatory combinations. In particular, it has been found that switching from standard MS therapies to fingolimod can trigger tumefactive lesions in some MS patients〔M.A. Hellmann, Tumefactive demyelination and a malignant course in an MS patient during and following fingolimod therapy, Journal of the Neurological Sciences Volume 344, Issues 1–2, 15 September 2014, Pages 193–197〕〔Totaro et al. Tumefactive Demyelinating Lesions in Patients with Relapsing Remitting Multiple Sclerosis Treated with Fingolimod, J Neurol Neurophysiol 2014, S12 ()〕〔YuanKai Lee et al. Tumefactive Multiple Sclerosis in a Patient on Fingolimod, Neurology April 8, 2014 vol. 82 no. 10 Supplement P2.226〕〔M.H. Harirchian et al. Emerging Tumefactive MS after switching therapy from Interferon-beta to Fingolimod; a case report, Multiple Sclerosis and Related Disorders, Available online 22 May 2015, doi:10.1016/j.msard.2015.05.007〕〔Timothy B Steinhoff, BS and Thomas F Scott, MD, Tumefactive Demyelination with White Matter Necrosis Following Cessation of Natalizumab Treatment, Neurological Cases VOL.2 NO.1 March 2015 ISSN 2374-3522 (PRINT) ISSN 2374-3530 (ONLINE)〕 While standard multiple sclerosis process has an autoimmune response after the breach of the blood-brain barrier, in tumefactive MS things do not process in the same way, and demyelinating lesions do not always show antibody damage. Subjects with tumefactive multiple sclerosis display elevated levels of choline (Cho)/creatine ratio and increased lactate which is associated with demylinating diseases. Cases also display oligoclonal bands in the cerebrospinal fluid.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tumefactive multiple sclerosis」の詳細全文を読む スポンサード リンク
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