Paraneoplastic opsoclonus-myoclonus associated with anti-Hu antibody.

We report a 74-year-old woman with opsoclonus, myoclonus, ataxia, and encephalopathy who had small-cell lung cancer and high titers of anti-Hu antibody in her serum. At autopsy, there were perivascular inflammatory infiltrates in the brainstem, putamen, and meninges overlying the orbital frontal cortex. Immunohistochemical studies showed the expression of the Hu antigens by the tumor and the presence of deposits of anti-Hu IgG in the patient's cortex, brainstem, and cerebellum, suggesting that anti-Hu immune response was related to the patient's clinical syndrome. This case of paraneoplastic opsoclonus, myoclonus, ataxia, and encephalopathy expands the spectrum of neurologic dysfunction associated with the anti-Hu antibody.