Anti-N-Methyl-D-Aspartate (NMDA) Receptor Encephalitis Secondary to an Ovarian Dermoid Cyst

Dermoid cysts, or mature cystic teratomas, are germ cell neoplasms that can arise on the ovaries. Being of germ cell origin, such cysts can have extensive variance in presentation, including a rare paraneoplastic effect where they produce N-methyl-D-aspartate receptor (NMDAR) antibodies, resulting in anti-NMDAR encephalitis. This can cause various neuropsychiatric symptoms, including confusion, hallucinations, psychosis, disorientation, and a change in cognition. This case study presents the unusual occurrence of a 39-year-old female patient who presented to the emergency department with encephalitis, headaches, and auditory hallucinations after recent glucocorticoid use. Through an extensive workup, imaging, and various physician consults, the patient was diagnosed with anti-NMDAR encephalitis secondary to a paraneoplastic effect originating from an ovarian dermoid cyst.