[18F]-FDG PET as a Diagnostic and Monitoring Tool in Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy: A Case Report.

A 58-year-old woman with autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy was explored using [18F]-fluorodeoxyglucose ([18F]-FDG) positron emission tomography (PET) before and after treatment with rituximab, an anti-CD20 monoclonal antibody. GFAP astrocytopathy was first suggested by magnetic resonance imaging showing a meningoencephalomyelitis, confirmed by anti-GFAP positivity. Before treatment, scintigraphic images evidenced encephalitis associated with diffuse cerebellar and brainstem hypermetabolism and panmyelitis. Significant scintigraphic improvement was observed 4 months after rituximab introduction, associated with an improvement of symptoms. This case report highlights the usefulness of [18F]-FDG PET in anti-GFAP astrocytopathy diagnosis, exploration of additional etiologies, and follow-up.