Immunopathological significance of ovarian teratoma in patients with anti-N-methyl-d-aspartate receptor encephalitis.

BACKGROUND: The clinical importance of ovarian teratoma in anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis has been established, however investigations of ovarian teratoma in patients with anti-NMDAR encephalitis remain limited.

OBJECTIVE: To clarify differences in NMDAR distribution and lymphocyte infiltration in ovarian teratoma between patients with and without anti-NMDAR encephalitis.

METHODS: Participants initially comprised 26 patients with ovarian teratomas. NMDAR distribution and lymphocyte infiltration in ovarian teratomas were examined using immunopathological techniques. Clinical, laboratory, and radiological data were compared between patients showing the features of encephalitis. Anti-NMDAR antibodies in the serum and cerebrospinal fluid were also measured in encephalitis patients.

RESULTS: Neuronal tissues were obtained from ovarian teratomas in 22 patients (after excluding 4 patients who did not satisfy the inclusion criteria), and the presence of NMDA receptor subunits was revealed in all patients. Lymphocyte infiltration was more frequent in the encephalitis group (n = 3) than in the non-encephalitis group. In particular, dense B-lymphocyte infiltration near neural tissues was observed in the encephalitis group.

CONCLUSIONS: Differences in lymphocyte infiltration in ovarian teratomas between anti-NMDAR encephalitis and non-encephalitis patients suggest the immunological importance of the ovarian teratoma as the site of antigen presentation in anti-NMDAR encephalitis.