pronounced CT-PET-findings and the history of excessive smoking led us to suspect a smoking-associated lung cancer. However, a histological tissue diagnosis was refused by the patient, as was subsequent oncologic therapy. Second, the isolated pattern of CASPR2 autoantibody positivity is interesting. Only one case of autoimmune chorea with a positive CASPR2 antibody has been reported, and it was an idiopathic case. This is according to a study on autoimmune chorea in adults, 4 in which the case of Ramdhani and Frucht1 can also be grouped. In the paraneoplastic group of autoimmune chorea, CASPR2 has not yet been reported. 4 On the other hand, CASPR2 is more often associated with neuromyotonia and Morvan syndrome and occurs more often in thymoma, 6 though these clinical findings were not present in our patient. However, it is informative that LGI1 (the antibody detected in the patients of Ramdhani and Frucht1 and of Toranis et al. 3) and CASPR2 are taken together as voltage-gated potassium channel (VGKC) complex autoantibodies and thus share substantial similarity. 7,8 To conclude, autoimmune processes must be considered in the differential diagnosis of adult-onset chorea. Besides laboratory and cerebrospinal fluid analysis, 9,10 a serum panel of autoantibodies, including LGI1 and CASPR2, may contribute to the diagnosis.

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