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.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. [Source: Wikipedia 
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