Delayed Ovarian Teratoma Resection in Anti–N-Methyl-D-Aspartate (NMDA) Receptor Encephalitis Despite Immunotherapy: Implications for Early Source Control

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is a severe autoimmune neurologic disorder frequently associated with ovarian teratomas in adult women.Tumor removal is a central component of management and is associated with improved neurologic outcomes.We report a 33-year-old woman with confirmed anti-NMDA receptor encephalitis complicated by refractory seizures, movement disorder, and prolonged ventilator dependence in whom ovarian teratoma resection was delayed after the family initially declined surgical intervention.Prior to surgical intervention, the patient received high-dose corticosteroids, plasma exchange (PLEX), intravenous immunoglobulin (IVIG), and rituximab, without meaningful clinical improvement.Pelvic imaging repeatedly failed to identify a definitive ovarian teratoma; however, gynecologic consultation recommended bilateral salpingo-oophorectomy.During the interval between the initial surgical recommendation and eventual family consent, the patient continued to demonstrate persistent severe neurologic dysfunction despite ongoing supportive and immunomodulatory therapy.Bilateral salpingooophorectomy was ultimately performed, and surgical pathology confirmed a mature ovarian teratoma.Despite tumor removal and escalation to cyclophosphamide, the patient remained ventilator-dependent with profound neurologic impairment.This case highlights the potential limitations of immunotherapy when an underlying antigenic source remains present and emphasizes the importance of maintaining suspicion for an occult ovarian teratoma and considering timely tumor-directed therapy in severe anti-NMDA receptor encephalitis despite inconclusive imaging.