A 9-year-old boy with hyper-IgM syndrome complicated by impaired consciousness and disseminated toxoplasmosis is reported from Nagoya University School of Medicine, Japan. X-linked hyper-IgM syndrome was diagnosed at 5 months of age and treated with IV immunoglobulin. On admission, he had involuntary movements and convulsions. CT and MRI showed multiple lucencies in subcortical white matter of frontal lobes and basal ganglia, without mass effect. Disseminated toxoplasmosis was diagnosed at autopsy, and microscopy showed necrotizing toxoplasmic encephalitis. 
COMMENT. X-linked hyper-IgM syndrome is an immunodeficiency disorder characterized by recurrent infections with opportunistic organisms, such as Pneumocystis carinii and Cryptosporidium, and associated with low serum levels of IgG and IgA, and normal to increased IgM. Disseminated toxoplasmosis is now added to the potential complications of this disorder.