Striatal hypermetabolism in a case of IgG4-related disease.

A 77 years-old man with lung and bone involvement of proven IgG4-related disease complained of tree month's memory deficits. Brain MRI was normal. 18F-FDG whole body PET/CT showed in addition to the bone lesions, a marked symmetrical striatal hypermetabolism in contrast with cortical hypometabolism. Despite steroid treatment, the patient's clinical status declined rapidly and he died two months later. Striatal hypermetabolism has been reported in autoimmune limbic encephalitis, but to the best of our knowledge, this is the first description in a case of IgG4-related disease.