A 19-year-old woman with seizurelike activity and fluctuating speech and behavior was ultimately diagnosed with anti–N-methyl-D-aspartate receptor encephalitis in association with a malignant mixed germ-cell tumor.
The case, reported by Judith A. Restrepo, MD, at Massachusetts General Hospital, and colleagues, began with slowed speech, right-sided numbness, and recurrent collapse with full-body shaking. Early evaluations showed an elevated lactate level, while repeated electroencephalography revealed no epileptiform activity. Despite antiepileptic therapy, she continued to have abnormal movements, intermittent mutism, and disorganized thought processes.
As her symptoms progressed, psychosis, agitation, and paranoia emerged. Neuroimaging remained normal and blood tests were largely unremarkable. On hospital day 2, cerebrospinal fluid analysis showed lymphocytic pleocytosis, supporting a presumptive diagnosis of anti–N-methyl-D-aspartate receptor encephalitis. Intravenous methylprednisolone was started on hospital day 3, followed by intravenous immune globulin on day 6 and surgery on day 7.
Pelvic imaging revealed multiple ovarian masses, including a 17-cm heterogeneous lesion. Surgical pathology confirmed a malignant mixed germ-cell tumor composed of immature teratoma (≈70% of tumor volume) and yolk-sac tumor components (≈30%).
“Autoimmune encephalitis is an uncommon but increasingly recognized disorder, and more than half of patients initially present with psychiatric symptoms, the most common of which is psychosis,” the authors noted.
Because of persistent symptoms, the patient received therapeutic plasma exchange and rituximab in addition to first-line therapy, with subsequent clinical improvement. At 7 months’ follow-up, she remained relapse-free on maintenance rituximab.
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