Chelsea Schmoll1, Stefanie Rodenbeck1, Katrina Collins2
1Neurology, 2Pathology, Indiana University
Objective:
To present a case report of a patient diagnosed with Kelch-like Protein-11 Encephalitis (KLHL11 encephalitis) to contribute valuable treatment insight into this rare neurological disorder.
Background:
Discovered in 2019, KLHL11 IgG represents a novel neural autoantibody, occurring predominantly in the presence of testicular germ cell tumors. Typically, this condition leads to a debilitating rhombencephalitis. Like other classic paraneoplastic neurologic syndromes, it often is refractory to immunotherapy.
Results:
44-year-old male presented with double vision, imbalance, and gait instability. Work up was undertaken including an MRI brain which was largely unremarkable. CSF revealed a lymphocytic pleocytosis, elevated protein, and unique oligoclonal bands in the CSF. An autoimmune encephalopathy panel was negative for all tested commercial autoantibodies. High dose methylprednisolone and plasmapheresis were initiated without significant improvement. IVIG did initially improve his symptoms, leading to improved ambulation and cessation of double vision. A testicular US revealed a hypoechoic lesion with biopsy revealing a regressed germ cell tumor. Whole body PET-CT was negative. Serum was positive for Kelch11 IgG. He was treated with plasmapheresis followed by cyclophosphamide induction. Symptoms progressed despite aggressive therapy. He is now wheelchair bound with significant central ataxia, diplopia, hearing loss, fatigue and dyspnea. Recently, rituximab and mycophenolate mofetil were initiated. He is also maintained on IVIG twice weekly and prednisone 30 mg daily.
Conclusions:
Our case underscores the common clinical phenotype KLHL11 encephalitis, an infrequent yet potentially manageable paraneoplastic condition. Ancillary testing typically reveals inflammatory CSF markers. While unusual, MRI may appear normal in up to 7% of KLHL11 encephalitis cases. Patients who are diagnosed with and receive appropriate chemotherapy for testicular germ cell tumors generally exhibit more favorable outcomes. This patient was found to have a regressed germ cell tumor, indicating a less optimistic prognosis despite aggressive immunotherapy, which aligns with approximately 19% of documented cases in the existing literature.