Ovarian teratomas causing anti-N-methyl-D-aspartate receptor encephalitis: a case series from west China

The incidence of ovarian teratomas (OT) causing anti-N-methyl-D-aspartate receptor encephalitis (anti-NMDARE) is low, and pathological studies of related cases are limited. This study aimed to analyze the clinical data of such patients and to investigate the expression of N-methyl-D-aspartate receptor (NMDAR) and lymphocytes in teratoma tissues to initially investigate the pathogenesis of the disease.

Clinical data were collected and analyzed. Immunohistochemistry was applied to detect the expression of NMDAR subunits and T/B lymphocytes in 46 patients, including 8 OT patients with encephalitis and 38 regular OT patients. Immunohistochemical expression of NMDARs and T/B lymphocytes in OT tissues in patients with or without anti-NMDARE.

Teratomas causing encephalitis mostly occur in young women. The degree of positive expression of NMDAR, CD4 and CD20 in the encephalitis group differed statistically from the control group (P<0.05). Although there was no linear relationship between the CD4/CD20 expression and the NMDAR expression, clusters of lymphocytes were observed clearly around the squamous epithelium positive for NMDAR expression only in the encephalitis group.

OT leading to encephalitis seems to be associated with high expression of NMDARs in the squamous epithelium of the tissue, where clusters of lymphocytes infiltration is also a unique pathological feature. This is the first multi-case group study about OTs causing anti-NMDARE in southwestern China.