Anti-NMDA receptor encephalitis from ovarian teratoma and mimicking psychosis: a report of a patient from a tertiary center in Pakistan

Introduction and Importance: Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is a severe but treatable autoimmune neurological disorder caused by antibodies against the NMDAR, a key modulator of synaptic plasticity, memory, and behavior. Initially characterized by Dalmau et al in 2007, it has emerged as the most common autoimmune encephalitis, especially among young women, often associated with ovarian teratomas. Early recognition and combined immunotherapy–surgical management are essential for favorable outcomes. Case Presentation: We report a 21-year-old woman who presented with acute behavioral disturbance, hallucinations, and seizures, initially misdiagnosed as a primary psychiatric illness. Cerebrospinal fluid analysis confirmed anti-NMDAR antibodies, while brain MRI revealed left temporal hyperintensities. Initial immunotherapy produced partial improvement. Pelvic MRI subsequently detected a left ovarian teratoma, which was surgically excised. Following resection and continued corticosteroid therapy, the patient achieved full neurological and psychiatric recovery. One-month follow-up revealed complete resolution of symptoms and normal functional status. Clinical Discussion: This case illustrates the diagnostic challenges of anti-NMDAR encephalitis in resource-limited settings, where early psychiatric features may delay recognition. Our experience emphasizes the critical role of gynecologic evaluation in young women with unexplained psychosis or seizures, even without pelvic symptoms. Prompt tumor removal combined with immunotherapy ensures optimal recovery. Conclusion: Anti-NMDAR encephalitis should be a leading differential in young women with new-onset psychosis and seizures. Early CSF antibody testing and pelvic imaging are vital to diagnosis, and multidisciplinary management can yield complete recovery.