Resection of melanocytic nevi as a potential treatment of anti-NMDAR encephalitis patients without tumor: report of three cases

The most common underlying tumor associated with anti-N-methyl d-aspartate-receptor (NMDAR) encephalitis is ovarian teratoma. Resection of the underlying tumor may decrease exposure of autoantigen and make for faster response of immunotherapy and less relapse frequency. Similar to teratoma, expression of NMDAR in human epidermal melanocytes was suspected recently. The dense melanocytes in melanocytic nevus may serve as potential autoantigens and are prone to increase relapse frequency in the tumor-negative patients. Three patients with confirmed diagnosis of anti-NMDAR encephalitis were described here. They shared common features that the screening tests for an ovarian teratoma or other tumors were all negative, while they were found to have prominent melanocytic nevi on the skin and resection of the nevi likely played a positive effect on their persistent recovery. This is a report on treatment of anti-NMDAR encephalitis patients without underlying tumor through resection of melanocytic nevi. More clinical and experimental investigations are needed to prove its validity.