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 inflamma
tory infiltrates in the brainstem, putamen, and meninges overlying the
orbital frontal cortex. Immunohistochemical studies showed the expres
sion of the Hu antigens by the tumor and the presence of deposits of a
nti-Hu IgG in the patient's cortex, brainstem, and cerebellum, suggest
ing 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 asso
ciated with the anti-Hu antibody.