ANNA-2: an antibody associated with paraneoplastic opsoclonus in a patient with large-cell carcinoma of the lung with neuroendocrine features--correlation of clinical improvement with tumor response.

This report describes a case of large-cell lung carcinoma with neuroendocrine features, presenting with the full clinical picture of paraneoplastic opsoclonus-myoclonus syndrome. The patient had an unexpectedly dramatic resolution of the neurologic dysfunction after receiving antineoplastic treatment. Symptom improvement paralleled a progressive decline of serum ANNA-2 antibody titers to undetectable levels.