Which of the following theories best explains how the presence of a teratomas may lead to Anti-NMDA encephalitis?

Question:

	1. People who have auto-immune disorders tend to have a high predilection for teratoma formation.
	2. The teratoma expresses neural receptor protein that is cross reactive to NMDA causing an immune response against the receptor in the brain.
	3. The teratoma secretes antibodies to NMDA.
	4. There have been no theories as to the relationship.
	5. When teratomas rupture the fat that is released crosses the blood brain barrier and localizes to the brain causing an inflammatory reaction.

Answer:

The correct answer for the question "Which of the following theories best explains how the presence of a teratomas may lead to Anti-NMDA encephalitis?" is:

2. The teratoma expresses neural receptor protein that is cross reactive to NMDA causing an immune response against the receptor in the brain.

Explanation
1. People who have auto-immune disorders tend to have a high predilection for teratoma formation. [Not been demonstrated in any epidemiologic study]

2. The teratoma expresses neural receptor protein that is cross reactive to NMDA causing an immune response against the receptor in the brain.

3. The teratoma secretes antibodies to NMDA. [The immune system secretes the antibody not the teratoma]

4. There have been no theories as to the relationship. [There is a robust theory available in the literature, with several supporting studies in both human and animal models]

5. When teratomas rupture the fat that is released crosses the blood brain barrier and localizes to the brain causing an inflammatory reaction. [Fat emboli cause infarcts, not encephalitis]

Citation: Hughes EG, Peng X, Gleichman AJ, Lai M, Zhou L, Tsou R, Parsons TD, Lynch DR, Dalmau J, Balic-Gordon RJ. Cellular and Synaptic Mechanisms of Anti-NMDA Receptor Encephalitis. The Journal of Neuroscience. April 2010. 30(17):5866 -5875. PMID: 20427647.

Seki M, Suzuki S, Iizuka T, Shimizu T, Nihei Y, Suzuki N, Dalmau J (2008) Neurological response to early removal of ovarian teratoma in antiNMDAR encephalitis. J Neurol Neurosurg Psychiatry 79:324 -326. PMID: 18032452.

From the manuscript:
Anti-NMDA Encephalitis: An Uncommon, Autoimmune Mediated Form of Encephalitis
Radiology Case. 2014 Aug; 8(8):1-6

This article belongs to the Neuro section.

From the manuscript

Anti-NMDA Encephalitis: An Uncommon, Autoimmune Mediated Form of Encephalitis

Free full text article: Anti-NMDA Encephalitis: An Uncommon, Autoimmune Mediated Form of Encephalitis

Abstract
We report an interesting case of a 19 year old female with findings on MRI suggestive of viral encephalitis. An extensive workup was negative for infectious causes and she was subsequently diagnosed with anti-NMDA encephalitis. Anti-NMDA encephalitis is a highly lethal but treatable form of autoimmune encephalitis that has recently been characterized. It is frequently found in young women and associated with an underlying teratoma. Although rare, this diagnosis should be considered in young females for whom a rapid onset of encephalitis cannot be explained by more common causes.

References

1. Nokura K, Yamamoto H, Okawara Y, Koga H, Osawa H,Sakai K. Reversible limbic encephalitis caused by ovarian teratoma. Acta Neurol Scand 1997 95(6) 367-373