A 68-year-old man presented with a 4-month history of progressive memory loss and mood disorders. Neurologic examination revealed severe impairment of attention and verbal skills, without motor and sensory deficits. His medical history included mild arterial hypertension, idiopathic partial epilepsy, and obsessive compulsive disorder. Brain MRI showed the presence of bilateral, asymmetric, swollen white matter lesions in the cerebral hemispheres, hyperintense in T2-weighted images, that partially involved the left frontal cortex (figure). On diffusion-weighted sequences, the white matter abnormalities were consistent with vasogenic edema. No pathologic contrast enhancement was present. Figure MRI of cerebral amyloid angiopathy–related inflammation (CAA-ri) and levels of anti-Aβ 1-40 and 1-42 autoantibodies in the CSF Axial fluid-attenuated inversion recovery brain MRI shows bilateral hyperintense lesions of the subcortical white matter (A), which are reduced after 20 days of steroid treatment (B). Axial T2*-weighted gradient-echo MRI (C) obtained 33 days later shows further reduction of white matter lesions and multiple, scattered, hypointense cortical lesions due to microhemorrhages (arrows). (D) Reiber's graph. X- and y-axes show, respectively, albumin (QAlb) and immunoglobulin G quotient (QIgG), obtained by the ratio between the level of the protein in the CSF from the first lumbar puncture and in the plasma. The QAlb indicates the permeability of the blood–brain barrier (BBB) to water-soluble molecules. The QIgG (total IgG including specific anti-Aβ autoantibodies) plotted into the graph discriminates between intrathecal production of IgG and …