Paraneoplastic limbic encephalitis due to lung squamous cell carcinoma

Paraneoplastic limbic encephalitis (PLE) is one of paraneoplastic neurological syndrome (PNS). We herein report a case of PLE due to lung squamous cell carcinoma. A 80-year-old woman visited because of several neurological symptoms. Brain magnetic resonance imaging revealed hyperintense signals at the splenium of the corpus callosum, suggesting limbic encephalitis. Chest X-ray and computed tomography showed a 17 × 14 mm tumor in the left lung field, suggesting lung cancer. Surgical examination revealed T1bN0M0 lung squamous cell carcinoma. She died 50 days after surgery due to the rapid progression of encephalitis. PLE is an extremely rare disorder, and even a case in the early stage of cancer shows poor prognosis. We should doubt a possibility of PLE, and detailed brain examination should be performed in case of consciousness disorder with rapid progression in the cancer patient.