GAD antibody positive paraneoplastic stiff person syndrome in a patient with renal cell carcinoma.

Stiff person syndrome (SPS) is an unusual cause of muscle rigidity and spasms. It is believed to have an autoimmune pathogenesis and is associated with autoantibodies to glutamic acid decarboxylase (GAD). Paraneoplastic SPS (PSPS) has been described mainly in relation to breast cancer and is associated with antibodies to amphiphysin. Few reports of PSPS document the finding of GAD autoantibodies. We present the first reported case of anti-GAD positive PSPS in a 53-year-old male with occult renal carcinoma. Clinical benefit was marked following nephrectomy and intravenous immunoglobulin treatment. Renal carcinoma should be considered in patients with SPS.