Systemic lupus erythematosus demonstrating serum anti-GM1 antibody, with sudden onset of drop foot as the initial presentation.

In systemic lupus erythematosus (SLE), peripheral neuropathies are relatively uncommon and rarely present as the initial symptom. We herein describe a 61-year-old woman who developed a sudden onset of drop foot, which was indistinguishable from Guillain-Barré syndrome based on the clinical symptoms alone. Antibodies against ganglioside GM1 were detected in the serum, while no antibodies to Campylobacter jejuni were observed. An electrophysiological study showed axonal impairment rather than demyelination. A pathological examination of a sural nerve biopsy specimen and further laboratory examinations suggested the observed peripheral neuropathies to have arisen due to lupus vasculitis. The serological activities of SLE responded well to treatment with corticosteroids, mizoribine and immunoadsorption therapies, however, the drop foot symptoms did not change remarkably.