January 2026

NEUROSCIENCES

CASE REPORT: AUTOIMMUNE ENCEPHALITIS WITH KLHL11 ANTIBODY IN AN 81-YEAR-OLD PATIENT

Clinical presentation
An 81-year-old woman presented with 4 months of progressive memory loss and 2 months of gait imbalance, nausea, vomiting and vertigo. During admission, she developed episodes of aphasia, right arm shaking and oral automatisms, confirmed as seizures originating from the left temporal region on EEG.

Initial evaluation
Serum studies were unremarkable, including conventional neural-specific autoantibodies. CSF analysis showed elevated protein (76 mg/dL), WBC count of 2/µL, and glucose of 68 mg/dL, with negative infectious studies and cytology. MRI revealed left mesial temporal T2/FLAIR hyperintensity (Figure 1). She started levetiracetam and was discharged.

Treatment and disease progression
Two weeks later, serum testing detected KLHL11 antibody by cell-based assay and tissue immunofluorescence (titer 1:7680). She was readmitted for autoimmune encephalitis treatment and malignancy workup. Neurological status worsened, with poor memory encoding, truncal ataxia and frequent involuntary right arm jerks.

Definitive diagnosis
CT imaging revealed enlarged lymph nodes; biopsy confirmed high-grade neuroendocrine carcinoma consistent with metastatic Merkel cell carcinoma. PET/CT demonstrated widespread hypermetabolic lymphadenopathy. The patient received IV methylprednisolone and plasmapheresis, followed by a prednisone taper. Outpatient therapy included mycophenolate mofetil and weekly plasmapheresis.

Key takeaways
  • KLHL11 antibody positivity should prompt evaluation for paraneoplastic syndromes, even when initial panels are negative.
  • Merkel cell carcinoma can present as metastatic disease without an identifiable primary site.
  • Early immunotherapy and seizure management are critical for stabilizing neurologic function.
  • Multidisciplinary coordination between neurology and oncology is essential for optimal care.
Shailee S. Shah, MD, Clinical Assistant Professor of Neurology (MS/Neuroimmunology) at Northwestern Medicine

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