A case of anti-N-methyl-D-aspartate receptor encephalitis with ovarian teratoma showing excellent recovery with decreasing of anti-N-methyl-D-aspartate receptor antibody

We report a case of a 17-year-old woman with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis, who developed psychiatric symptoms. Pelvic MRI revealed a right ovarian tumor that was suspected of being an ovarian teratoma. On the 27^th day after onset, the patient underwent right salpingo-oophorectomy. The histopathological diagnosis was immature ovarian teratoma. Subsequently, 4 double filtration plasmapheresises (DFPP) were performed from day 34 to day 43. Methylprednisolone (1,000 mg/day for 3 days) was started on day 38. With these treatments, consciousness disturbance completely improved, and the patient was discharged on day 50. The serum and cerebrospinal fluid were positive for antibodies against the GluRζ1 (NR1)-EGFP/GluRε2 (NR2B) heteromer and the GluRζ1 (NR1) subunit of NMDAR. The patient was hence diagnosed as having anti-NMDAR encephalitis with ovarian teratoma. Serial analysis show that the antibodies against NMDAR decreased with improvement of symptoms after the immunotherapy including DFPP treatment.