A Nine‐Year Diagnostic Odyssey of Refractory Psychiatric Symptoms Resolving After Resection of a CA19‐9‐Producing Ovarian Teratoma: A Case Report and Literature Review

BACKGROUND: Ovarian teratomas are increasingly recognized as triggers for autoimmune processes, including neuropsychiatric syndromes. This report describes a rare case of isolated autoimmune psychosis associated with an ovarian teratoma and reviews the relevant literature. CASE PRESENTATION: A 15-year-old female with a 9-year psychiatric history was initially diagnosed with schizophrenia. Her symptoms, refractory to multiple antipsychotic regimens, included emotional instability, impulsive aggression, and perceptual abnormalities. Abdominal ultrasonography revealed a giant ovarian teratoma with significantly elevated CA19-9. Histopathology confirmed neural tissue. Following tumor resection, her psychiatric symptoms resolved dramatically, enabling a return to normal schooling. LITERATURE REVIEW: Our systematic review identified 32 cases of teratoma-associated psychosis. Notably, only 2 cases (7.7%) presented without encephalitic features, with one being seronegative for NMDA antibodies. This highlights the exceptional nature of our "pure" psychiatric presentation. CONCLUSIONS: Ovarian teratomas may be associated with suspected cases of isolated autoimmune psychosis, even in the absence of typical neurological signs or positive autoantibodies. In such instances, CA19-9 elevation could serve as a nonspecific clue. Comprehensive imaging remains crucial for patients with atypical, treatment-resistant psychosis to avoid diagnostic delays.