Possible paraneoplastic etiology in a case of Guillain-Barré syndrome with tumoral expression of ganglioside GM3

Abstract

Paraneoplastic neurological syndromes occur most frequently with small cell lung cancer. We report a 73-year-old man who had suffered from small cell lung cancer, with a fraction of the patient's malignant cells expressing membrane ganglioside GM3, and had developed Guillain-Barré syndrome with serum positivity for anti-GM3 immunoglobulin G antibody when assayed with phosphatidic acid. The distribution of GM3 in myelin labeled with anti-human GM3 antibodies corresponded well to that labeled with the patient's serum, but not with control sera. Intravenous immunoglobulins and chemotherapy for cancer resolved the symptoms of Guillain-Barré syndrome. These observations suggest that autoantibodies against conformational epitopes formed by GM3 and phosphatidic acid in cancers cross-react with neural tissue, probably as a result of molecular mimicry, and might thus underlie paraneoplastic Guillain-Barré syndrome.