Unusual case of anti-N-methyl-D-aspartic acid-receptor (NMDA-R) encephalitis and autoimmune polyglandular syndrome (APS)

Anti-N-methyl-D-aspartic acid-receptor (NMDA-R) encephalitis is a novel disease discovered within the past 10 years. It is an autoimmune disease (AD) that has been associated with other ADs, such as Graves' disease. However, association with autoimmune polyglandular syndromes (APS) has not been previously described. A 58-year-old woman presented with altered mental status and an 8-month history of weight loss, apathy and somnolence. Laboratory evaluation confirmed Graves' disease with thyrotoxicosis and type 1 diabetes mellitus. Despite treatment, she continued to have a fluctuating mental status. Further diagnostic evaluation included an abdominal MRI that showed a cystic lobular left adnexal mass. Serum anti-NMDA-R antibodies were positive, raising concern for NMDA-R encephalitis. Bilateral salpingo-oophorectomy was performed, with pathology consistent with cystadenofibroma. She had a favourable recovery with marked clinical improvement. Anti-NMDA-R antibodies were negative 2 months following surgery. The concomitant occurrence of APS and anti-NMDA-R encephalitis suggests a shared mechanism of autoimmune pathophysiology.