Refractory Anti- N -Methyl- d -Aspartate Receptor Autoimmune Encephalitis Induced by Ovarian Teratoma: A Case Report

Teratoma is a type of germ cell tumor that derived from early embryonic stem cells and germ cell lines, which can lead to a rare complication known as paraneoplastic encephalitis syndrome. Delayed removal of teratoma allows for continuing antigen presentation, inducing affinity maturation of the antibody and the generation of long-lived plasma cells that infiltrate both bone marrow and brain, which makes the patient nonresponsive to later removal of teratoma and refractory to immunotherapy. We present this rare case to remind clinicians to be vigilant for the recognition and removal of teratoma during the treatment of autoimmune encephalitis.

We retrospectively reviewed the clinical record of this 12-year 5-month-old female patient diagnosed with anti- N -methyl- d -aspartate receptor (anti-NMDAR) autoimmune encephalitis; her ovarian teratoma was unidentified on admission. She did not respond to immunosuppressive therapy until the mature ovarian teratoma identified 45 days after admission and removed the following day, nearly 2 months after symptom onset. This patient experienced nearly complete resolution of symptoms within the subsequent 2 weeks. In addition, we conducted a literature review of the clinical presentations and treatment of anti-NMDAR autoimmune encephalitis associated with ovarian teratoma in the pediatric population.

Our findings suggest that clinicians should be vigilant for the recognition and removal of teratoma during the treatment of autoimmune encephalitis.

Female pediatric patients with suspected anti-NMDAR encephalitis should be screened for ovarian tumors immediately and treated in a multidisciplinary setting including neurology and obstetrics and gynecology.