Hemichorea in a thymoma patient without anti-CRMP-5 antibody.

We reported a 72-year-old man with thymoma who presented with hemichorea. Although his brain CT and MRI revealed no abnormality, regional cerebral blood flow changes, identified by single photon emission computed tomography, suggested that the mechanism underlying the chorea seemed to be a dysfunction of the subthalamic nucleus and pallidum. His hemichorea was completely resolved after thymectomy. Absence of serum anti-neural autoantibodies, including small-cell lung carcinoma-related chorea anti-CRMP-5 antibody, suggests that mechanisms different from cross-talk neural-targeted tumor immune response can be responsible for the thymoma-associated paraneoplastic chorea.