We present the case of a 17-year-old female diagnosed with a teratoma in the setting of GFAP encephalitis following a febrile illness, to assist in early recognition, diagnosis, and treatment of this debilitating disorder.

GFAP encephalitis is defined by the presence of GFAP-reactive autoantibodies in patients with central nervous system (CNS) inflammation. Clinically, autoimmune GFAP encephalitis presents with a subacute onset of cognitive changes with or without psychiatric symptoms, meningeal symptoms, and/or myelopathic symptoms, sometimes after a preceding infection. Distinct radiologic features, GFAP-targeted IgG, and clinical presentation should alert clinicians to an immune-mediated and typically corticosteroid-responsive disorder.

An adolescent female developed subacute behavioral changes, intermittent high fevers, headaches, visual changes, urinary incontinence, and facial numbness. Initial work-up revealed bilateral papilledema, marked CSF pleocytosis (259/cumm), elevated protein (114 mg/dL), and GFAP-IgG. Brain magnetic resonance imaging (MRI) exhibited subtle T2 hyperintense periventricular radial, linear, and perpendicular projections, with slight contrast enhancement. An ovarian teratoma was discovered and resected.

She was initially treated with 5-days of intravenous methylprednisolone (IVMP), plasmapheresis, intravenous immunoglobulin (IVIg), and one dose of Rituximab, followed by a 6-week prednisone taper, with initial improvement. However, as steroids were tapered, her symptoms recurred. She was treated with monthly IVIg, with little improvement. On second clinical opinion nearly a year later, she was bridged to mycophenolate mofetil with a gradual 3-month taper of IVMP.

Detection of CSF GFAP-IgG is highly specific for an autoimmune encephalitis that can be associated with a parainfectious and/or paraneoplastic etiology, even in adolescents. It is known to respond to steroids, although recurrence sometimes necessitate transitioning to steroid-sparing agents. Strong suspicion based on clinical presentation with paraclinical evidence, including MRI and CSF findings, should prompt early initiation of high-dose steroids with a slow taper, to halt disease progression and prevent a relapsing course.