Anti-NMDA receptor encephalitis is most classically associated with which tumor?

• A. Testicular teratoma
• B. Lung carcinoma
• C. Ovarian teratoma
• D. Breast cancer

Answer: (C)

Anti-NMDA receptor encephalitis is most classically linked to ovarian teratomas, especially in young women. Teratomas can contain neural tissue that expresses NMDA receptors, which can provoke an immune response that makes antibodies against these receptors. Those antibodies then target NMDA receptors in the brain, leading to the rapid development of psychiatric symptoms, seizures, movement disorders, autonomic instability, and sometimes respiratory compromise. Identifying and removing the teratoma often improves outcomes and reduces relapse risk, with immunotherapy (steroids, IVIG, plasmapheresis) used as well.

In men, a related association can occur with testicular germ cell tumors, but the classic, most recognized tumor is ovarian teratoma. Lung or breast cancers are not typically associated with this condition.