[A case of lung adenocarcinoma presenting with chorea with bilateral basal ganglial lesions on MRI].

The patient, a 63-year-old man, experienced the subacute onset of chorea, for which his family doctor prescribed oral haloperidol. However, the involuntary movements gradually worsened, and the patient was referred and admitted. High-signal lesions were seen in the caudate nucleus, putamen and globus pallidus bilaterally on MRI T2-weighted and FLAIR images. Chest CT, FDG-PET and tissue biopsies also revealed that the patient had lung adenocarcinoma with multiple lymph node metastases. The patient was diagnosed as having paraneoplastic chorea associated with primary lung adenocarcinoma. Antineuronal antibodies, such as anti-CRMP-5 and anti-Yo antibodies, were absent. The patient received steroid pulse therapy, oral prednisolone therapy, and concurrent radiochemotherapy. Chorea and high-signal lesions in the corpus striatum bilaterally on MRI improved quickly, and the mediastinal lymph node swelling also improved. The patient has been stable for 3 years since the onset of his symptoms. As the prognosis of paraneoplastic chorea is relatively favorable in some patients, it should be considered in the differential diagnosis of patients with chorea.