Choreoathetosis as a rare complication of paraneoplastic syndrome: a case report in small cell lung cancer with positive anti-Hu antibodies.

Choreoathetosis is a rare complication of paraneoplastic syndrome, particularly associated with small cell lung cancer. We report a case of an elderly woman with small cell lung cancer who was diagnosed with choreoathetosis due to autoimmune-mediated paraneoplastic syndrome. The differential diagnoses for focal neurological deficits such as stroke, immunotherapy-related toxicity, radiation-induced toxicity, and brain metastasis were considered but the presence of onconeural antibodies made paraneoplastic syndrome a more likely diagnosis. Management of choreoathetosis in paraneoplastic syndrome can be challenging, with limited treatment options available.