Tumefactive demyelination-an unusual neurological presentation of HIV.

We describe 3 individuals infected with human immunodeficiency virus with unusual focal brain syndromes; magnetic resonance imaging revealed "open-ring" pattern space occupying lesions. After deterioration while the patients were receiving anti-Toxoplasma therapy, brain biopsy was performed, which revealed aggressive demyelination consistent with tumefactive demyelination. Treatment with high-dose steroids resulted in complete recovery in all cases.