Recurrent tumefactive demyelination in a child.

A 13-year-old female presented with two episodes of hemiplegia and hemianopia involving opposite sides, each time associated with seizures. On both occasions, the magnetic resonance (MR) scan showed a giant demyelinating, peripherally enhancing lesion with mass effect. MR spectroscopy (MRS) was indistinguishable from a tumor. At the first episode, she had undergone tumor decompression but the histopathology revealed an acute demyelinating lesion with no evidence of tumor. Each time there was partial clinical recovery and resolution of the radiological lesion, the patient having received corticosteroids during both of the episodes. She also developed hemiballismus postoperatively which resolved on withdrawing phenytoin. It is suggested that a trial of corticosteroids be given in suspected tumefactive demyelinating lesions, although they may be indistinguishable from a tumor.