N-Methyl-D-Aspartate Receptor-Negative Autoimmune Encephalitis in a Patient With an Ovarian Teratoma and an Associated Novel Cerebrospinal Fluid Autoantibody.

Autoimmune encephalitis is most commonly caused by autoantibodies against N-methyl-D-aspartate (NMDA) receptors, and the malignancy most often associated with anti-NMDA receptor autoimmune encephalitis is an ovarian teratoma. Here, we describe a case of autoimmune encephalitis caused by a newly discovered cerebrospinal fluid autoantibody that has not been previously described and is not anti-NMDA receptor-mediated, which has been associated with an ovarian teratoma. It was successfully treated with high-dose corticosteroids and plasmapheresis followed by rituximab and chemotherapy (paclitaxel, ifosfamide, and cisplatin) for her teratoma.