Anti-NMDAR Encephalitis associated with teratoma typically have low relapse rate (15-24%). In this case report, patient relapsed in the setting of recurrent teratoma after cystectomy.

Teratomas can induce production of antibodies that lead to anti-NMDAR encephalitis. Early detection and removal of teratoma favor long-term good prognosis. Recurrence rate of teratoma after resection is 4.2%. The paucity of data regarding the rate of anti-NMDAR encephalitis relapse with recurrence of ovarian teratoma contributes to uncertainty in clinical practice regarding surveillance imaging.  

A 22-year-old reasonably healthy female presented with fevers, seizure activity, and 3 weeks of psychotic features including delusional thoughts and hallucinations. Lumbar puncture revealed mild pleocytosis, negative meningitis panel, negative cultures. MRI brain showed hyperintensity in left hippocampal temporal area. LTM EEG showed right hemispheric slowing, with occasional GRDA. Repeat LTM EEG captured nonconvulsive status epilepticus controlled with antiseizure medications (ASM). CT chest/abdomen/pelvis revealed 4 cm right ovarian cystic teratoma. Patient underwent right ovarian cystectomy, pathology confirmed mature cystic teratoma. Autoimmune encephalopathy panel NMDAR antibody (CSF) positive. She underwent treatment with 5 days of plasma exchange followed by induction dose Rituxan and discharged on ASMs. Outpatient follow-up for continued ASM management, neuropsychiatric symptoms, and immunosuppression therapy with Rituxan every 6 months. Routine repeat CT chest/abdomen/pelvis 13 months after teratoma resection notable for 4 cm recurrent teratoma. On follow up after CT scan obtained, patient exhibiting worsening psychotic symptoms, prompting hospital admission for anti-NMDAR encephalitis relapse. Patient underwent IVIG x 5 days and right ovarian oophorectomy, which confirmed mature cystic teratoma. Hospital follow-up with improved neuropsychiatric symptoms.

Our case highlights the importance of monitoring for teratoma recurrence in addition to anti-NMDAR encephalitis relapse. Vigilance is important as early detection and resection of recurrence improves prognosis. Currently, no guidelines exist for surveillance imaging, and further data is needed for best practices.