Abnormal FDG Uptake in the Spinal Cord in Autoimmune Glial Fibrillary Acidic Protein (GFAP) Astrocytopathy

A 60-year-old man was admitted to the Department of Neurology presenting with general malaise, myoclonus, bladder dysfunction, and weight loss. Examination revealed hyperreflexia, and cerebrospinal fluid analysis demonstrated pleocytosis and elevated total protein. The initial MRI did not reveal apparent abnormalities. The differential diagnosis included autoimmune disorders, malignancy, or infection. FDG-PET/CT, performed to exclude malignancy, only showed increased spinal cord activity. Laboratory tests ruled out most infections, and the patient received 1000 mg methylprednisolone for suspected autoimmune disease. The diagnosis of autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy was confirmed by anti-GFAP antibodies detected in an academic laboratory.