Abstract
Tumefactive demyelinating lesion is defined as large solitary demyelinating lesion with imaging characteristics mimicking neoplasm. These atypical features include size more than 2 cm, mass effect, edema, and/or ring enhancement. Distinguishing tumefactive lesions from other etiologies of intracranial space occupying lesions is essential to avoid inadvertent surgical or toxic chemotherapeutic intervention. Symptoms are generally atypical for multiple sclerosis (MS) and usually related to the pressure of a focal mass lesion without a history of MS. The clinical presentation and MRI appearance of these lesions often lead to biopsy. Here, we present a young man with fulminating neurological symptoms and multiple large tumefactive lesions on either hemisphere. Since patient and parents were not agreed on brain biopsy, a course of steroid therapy was commenced which ended to considerable improvement and confirmed the diagnosis of tumefactive MS. Thirteen months later, he experienced another relapse when his treatment was continued by weekly intramuscular injection of interferon b1a (Avonex). Two further MRIs showed shrinkage of tumefactive plaques and resolution of edema in the periphery of lesions.