Anti-kelch-like protein 11 antibody-associated encephalitis: two case reports and literature review

Background Anti-Kelch-like protein 11 (KLHL11) antibody-associated encephalitis is a rare autoimmune neurological disorder, typically presenting with cerebellar syndrome and brainstem involvement. Diagnosis depends on the detection of anti-KLHL11 antibodies in serum and/or cerebrospinal fluid (CSF). Immunotherapy remains the cornerstone of treatment. Case presentation Patient 1 presented with an acute onset of dizziness, limb weakness, and sluggish responses, with rapid progression of symptoms. Despite receiving immunotherapy, including intravenous corticosteroids, immunoglobulin, and plasma exchange, which resulted in partial improvement, the patient rapidly relapsed, and his condition worsened. Ultimately, he succumbed to central circulatory failure. Patient 2 exhibited a relatively slow disease progression, primarily characterized by gait difficulties, slurred speech, and memory decline. He received only symptomatic treatment and did not undergo immunotherapy. Follow-up assessments indicated slight improvement in his symptoms. Brain magnetic resonance imaging (MRI) in both patients revealed abnormal findings, while initial serum cell-based assay (CBA) testing detected anti-KLHL11 antibody titers of 1:30 and 1:100, respectively. Conclusion This study highlights the clinical heterogeneity of anti-KLHL11 antibody-associated encephalitis and the significant challenges involved in its diagnosis and management. In patients presenting with acute or subacute ataxia—particularly when accompanied by symptoms such as dizziness or hearing loss—clinicians should maintain a high index of suspicion for KLHL11-IgG–associated encephalitis after excluding other potential etiologies. Timely antibody testing and tumor screening are crucial for accurate diagnosis and early initiation of treatment.