Fig. 1. Gadolinium-enhanced T1-weighted axial and coronal views and a T2-weighted FLAIR axial view in patient 1. A: Postcontrast T1-weighted MRI showed extensive thickening and enhancement of the dura mater along the left frontal parietal convexities. T2-weighted FLAIR MRI revealed diffuse cortical edema under the thickened dura mater. B: After treatment with corticosteroid, brain MRI disclosed marked decreases in dural thickening and cortical swelling. C: After 7 months of corticosteroid treatment, aggravation of dural thickening and cortical swelling were prominent. D: After treatment with rituximab, 3-month follow-up MRI showed normal cerebral dura mater and cortex. FLAIR: fluid attenuated inversion recovery.