Objective:

To report a case of a 58-year-old female with history of lung adenocarcinoma who developed GFAP longitudinally extensive myelitis secondary to immune-checkpoint inhibitor (ICI) pembrolizumab. 

Background:

GFAP astrocytopathy is an inflammatory autoimmune disorder described in 2016 most often characterized by meningoencephalitis though can also involve the spinal cord and optic nerve. The disorder is often monophasic and corticosteroid-responsive, however 20% of patients have a relapsing course necessitating steroid-sparing therapies.

Design/Methods:

Case report/literature review 

Results:

The patient initially developed subacute encephalopathy and dizziness which resulted in admission to an outside hospital. MRI brain was unremarkable. Work up revealed marked CSF pleocytosis (213/uL) and elevated protein (205 mg/dL). She was then treated with intravenous steroids for presumed ICI encephalitis given that she was on pembrolizumab. ICI therapy was put on hold. She was discharged to rehab where she had worsening weakness in bilateral lower extremities and could not ambulate. She was then admitted to our institution where MRI of cervical and thoracic spine showed longitudinally extensive myelitis through entire length of the cord with prominent diffuse cord edema with associated enhancement. Repeat CSF revealed pleocytosis (177/uL with 92% lymphocytes), elevated protein (264 mg/dL) and 7 oligoclonal bands.  CSF infectious workup was negative.  GFAP antibody subsequently returned positive in the CSF (1:128).  The patient was treated with 5 days of intravenous steroids and started on a long steroid taper (1 mg/kg). She was then transitioned to intravenous immunoglobulin (IVIG) taper schedule and rituximab (2 doses) with significant clinical and radiological improvement. 

Conclusions:

Detection of CSF GFAP-IgG is highly specific for GFAP autoimmune meningoencephalomyelitis. Our literature review showed only a handful of cases who developed autoimmune GFAP-associated myelitis secondary to ICI which highlights the need for high clinical suspicion. These conditions usually have favorable steroid responsiveness although suboptimal functional outcomes require prolonged immunotherapy protocols.