Behavior Change in a Young Woman: The Secret Lies in the Ovarian Tumor Matthew Moritz, MD; Linh Tang Taylor, MD; Olivia Snir, MD;
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Publication Date
4-29-2026
Keywords
oregon, psvmc, psvmc gme, psvmc oaa
Disciplines
Medical Education
Abstract
Introduction: Autoimmune encephalitis is a rare immune-mediated disorder characterized by neuropsychiatric symptoms. Anti-NMDA receptor (NMDA-R) encephalitis, the most common subtype, affects approximately 1 in 1.5 million people annually. We present a case of a young female with new-onset hallucinations, behavioral changes, and personality disturbance. Case Presentation: A 32-year-old female with remote methamphetamine use and recent trauma presented with acute mental status changes, aggression, emotional lability, and hallucinations. Vitals were normal; on exam she appeared confused, agitated, and displayed unusual behavior, including hallucinations. Initial evaluation revealed mild leukocytosis, but otherwise normal urine drug screen, chest radiograph, TSH, ANA, VDRL, heavy metal panel, infectious and autoimmune encephalitis panels, and brain MRI. Lumbar puncture (LP) revealed fourteen nucleated cells, ninety-two percent lymphocytes, and six red blood cells. Psychiatry was consulted but felt this was unlikely to represent a primary psychiatric disorder. Neurology recommended repeat LP and initiation of empiric methylprednisolone, IVIG, and plasmapheresis for presumed autoimmune encephalitis. CT abdomen/pelvis revealed a five-centimeter dermoid cyst on the right ovary. She underwent right salpingoopherectomy with pathology showing a cystic teratoma with mature neuronal tissue. The CSF encephalitis panel returned positive for NMDA-R. She completed five sessions of plasmapheresis and one dose of rituximab induction. Her agitation and behavioral disturbances were slow to resolve, requiring high-dose antipsychotics and benzodiazepines, but she was ultimately discharged with close outpatient neurology follow -up and a plan for a second rituximab dose. Discussion: Due to its rarity and nonspecific symptoms, autoimmune encephalitis is often overlooked in clinical practice. Furthermore, our patient’s age and recent traumatic experience prompted a primary psychiatric diagnosis to be pursued. This case underscores the importance of assessing symptom onset, as primary psychiatric disorders such as schizophrenia or bipolar disorder typically present with a more gradual, insidious onset— unlike the acute presentation seen in our case. When suspected, a basic workup should include a brain MRI, lumbar puncture, and neuronal autoantibody testing, though brain MRI findings may be normal. Both serum and CSF should be tested for neuronal autoantibodies, as CSF offers greater sensitivity—particularly for NMDA receptor antibodies, as demonstrated in our case where only CSF testing yielded a positive result. In anti-NMDA receptor encephalitis, IgG antibodies against NR1 are often triggered by neural tissue in ovarian teratomas via molecular mimicry. Once autoimmune encephalitis is diagnosed, evaluation for an underlying malignancy should follow, as treatment of a paraneoplastic process is integral to disease management. In our case, an ovarian teratoma—commonly associated with anti-NMDA receptor encephalitis—was identified and resected, contributing to clinical improvement
Specialty/Research Institute
Graduate Medical Education
Specialty/Research Institute
Internal Medicine
