Spontaneously changing MRI findings of primary central nervous system vasculitis: A case report.

Spontaneously disappearing lesions on magnetic resonance imaging (MRI) has been described in primary central nervous system lymphoma. In this case, we report our experience of spontaneously changing MRI findings of primary central nervous system vasculitis (PCNSV) confirmed histopathologically. A 69-year-old man presented with sudden unsteady gait. Fluid-attenuated inversion recovery (FLAIR) images showed high-intensity areas in the right deep white matter. Contrast-enhanced T1-weighted MRI demonstrated a nodular lesion in the white matter of the left occipitoparietal lobe. On repeat MRI 7 days later, FLAIR hyperintense lesions had spontaneously disappeared and contrast-enhanced lesions had progressed, with new contrast lesions in the right corpus callosum. Repeat MRI 14 days after admission demonstrated contrast-enhancing lesions either increased or decreased in intensity in both occipitoparietal lobes. Contrast-enhancing lesions were therefore biopsied. Histopathological examination revealed vasculitis with fibrinoid necrosis. PCNSV was diagnosed without any signs of inflammation in blood vessels other than cerebral blood vessels. Spontaneously changing MRI findings may play an important role in diagnosing PCNSV.