Empirical treatment with methylprednisolone had only suboptimal effects. Repeated brain MRI revealed growth of the lesion in the right thalamus while the lesions in the limbic lobes subsided. Another course of methylprednisolone failed to improve her neurological deficit or radiological abnormality. Because the multiple lesions in the brain parenchyma were considered to be progressing as a whole, a brain biopsy was planned.