Focal Seizures Induced by Paraneoplastic Syndrome Leading to a Diagnosis of Small Cell Lung Carcinoma

Paraneoplastic neurological disorders are a rare complication of multiple neoplasms, such as lung, testis, and breast, and can be associated with positive antibody anti-Hu (anti-neuronal nuclear antibody type 1 or ANNA-1), anti-Ta, anti-Ma, and uncharacterized antibody, or be antibody-negative. Early treatment of the underlying tumor is the most likely modality that will lead to regression of the paraneoplastic neurological symptoms. Here, we present a case of a 73-year-old female with new-onset seizure activity from ANNA-1 encephalitis found to have undiagnosed small cell lung cancer to highlight the need for further workup for malignancy.