Neurology · Oncology ·
RIMKLA-IgG Identified in Paraneoplastic Ataxia Case Series
A multicenter case series identified RIMKLA-IgG in 8 patients with progressive cerebellar and hindbrain symptoms; 6 had small cell lung cancer. The findings suggest a potential diagnostic biomarker for paraneoplastic neurological syndrome, but its clinical performance and generalizability require further study.
- RIMKLA-IgG was found in 8 of 35 referred patients.
- Six of the eight patients had small cell lung cancer.
- All eight had inflammatory cerebrospinal fluid.
- Clinical utility requires validation in larger cohorts.
Investigators used cell-based and tissue-based assays to screen samples from patients with suspected autoimmune neurological disease and validate candidate antibodies. Among 35 referred patients, 8 (median age 65 years; 6 men) had IgG targeting RIMKLA, an intracellular neural protein. The work began with a patient with small cell lung cancer, inflammatory cerebellar ataxia, and negative results on known paraneoplastic antibody panels; screening identified 7 additional patients with a similar clinical profile.
Patients had progressive cerebellar ataxia, with features including diplopia, cranial nerve VI paresis, and sensory or motor abnormalities. Six of the 8 patients had small cell lung cancer, and all had inflammatory cerebrospinal fluid and intrathecal immunoglobulin synthesis. The authors propose RIMKLA-IgG as a biomarker for an intracellular-antigen paraneoplastic syndrome involving the cerebellum and hindbrain, with possible peripheral and motor involvement.
This small case series describes a candidate antibody that may help identify some patients whose results are negative on established panels. It does not establish test accuracy, prevalence, or whether antibody detection changes outcomes; broader validation is needed before its clinical utility can be determined.
In practice
For patients with progressive cerebellar ataxia and a suspected paraneoplastic syndrome—particularly when established antibody panels are negative—RIMKLA-IgG is a newly reported candidate biomarker. In this case series, 8 patients had the antibody, 6 with small cell lung cancer, and all had inflammatory CSF. These findings may inform diagnostic investigation, but the evidence is limited to a small selected series; test accuracy, prevalence, and whether testing improves management or outcomes remain unestablished. The report does not support changing practice on its own.
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JAMA Neurology: Identification of RIMKLA-IgG Paraneoplastic Neurological Syndrome With Cerebellar Ataxia ↗This is an automated AI-condensed summary that has not yet been reviewed by an editor. Always consult the full item at the original source.