Pseudotumoral Demyelinating Lesions: A Presentation of Acute Disseminated Encephalomyelitis.

Pseudotumoral forms of demyelination are related to central nervous system demyelinating disorders, usually considered to be an atypical presentation of multiple sclerosis including its different varieties such as Balo's, Schilder's, and Marburg diseases. These lesions could also be seen in myelin oligodendrocyte glycoprotein antibody-associated demyelination, acute disseminated encephalomyelitis (ADEM), and neuromyelitis optica spectrum disorder. The pseudotumoral aspect may be mistakenly considered as an abscess or a cancerous tumor, in which case, patients could endure unnecessary possibly harmful brain biopsy and have a delay in their disease diagnostics and management. Once latter differential diagnosis is discarded, pseudotumoral demyelination prompts uncertainties concerning the nature of the underlying demyelinating condition as prognosis and management differ from multiple sclerosis to other syndromes, especially whether a chronic treatment is needed or not. In this case report, we present a 35-year-old male patient hospitalized in the department of neurology for a rapidly progressive onset of encephalopathy and polyfocal neurological deficits, with pseudotumoral lesions shown on brain MRI. On further investigations, ADEM was the more likely diagnosis that could fit the patient's clinical and radiological presentation. Thence, he was put on high dose of intravenous corticosteroids, with a followed good recovery within the first week of the treatment.