Tumefactive Multiple Sclerosis (TMS) is a rare type of Multiple Sclerosis (MS) that is defined by the presence of large demyelinating lesions with mass effect. While TMS is a specific medical term, there are several synonyms that can be used to describe this condition. Some of these include Tumefactive demyelinating disease, Tumefactive MS, Focal progressive leukoencephalopathy and Tumorous MS. Regardless of the terminology, this condition requires careful management by a skilled healthcare team, as it can lead to progressive disability, neurological damage and other complications. Early diagnosis and treatment are crucial for ensuring the best possible outcomes for patients with TMS.