A case of autoimmune GFAP astrocytopathy with profound weight loss and increased uptake in the spinal cord on ¹⁸F-FDG PET

A 76-year-old man presented with subacute onset of progressive cognitive impairment, anorexia, tremor, ataxic gait, and urinary dysfunction. He had lost 17 kg in 9 months before his admission (due to persistent anorexia). A brain MRI showed a typical radial pattern of periventricular gadolinium enhancement and longitudinally extensive hyperintensity from cervical to lumbar spinal cord. ¹⁸F-FDG PET newly revealed an increased uptake of the tracer in the cervical and lower thoracic cords. After an intravenous methylprednisolone (1000 mg/d for 3 days) followed by oral prednisolone 40 mg/d, his clinical symptoms and abnormal MRI lesions improved. Anti-GFAP antibodies were subsequently identified in CSF obtained on admission, confirming the diagnosis of autoimmune GFAP astrocytopathy.