Added diagnostic utility of PET in a patient with subacute encephalopathy and small-cell lung cancer.

Diagnosis of paraneoplastic neurologic disorder (PND) synthesizes the clinical picture (including the temporal relationship to the cancer diagnosis), detection of onconeural antibodies and exclusion of alternative causes. The mainstay of brain imaging of PNDs is MRI. There is also an increasingly recognized role of PET using radiotracer F-Fluorodeoxyglucose (FDG) in the evaluation of the brain. We describe a 67-year-old female with a 50-year smoking history and small-cell lung cancer developing subacute encephalopathy with MRI and PET abnormalities identifying paraneoplastic encephalitis. PET may complement conventional tools in diagnosing a subset of patients with PND.