[Autoimmune Encephalitis Associated with Malignant Tumors]

Autoimmune encephalitis consists of limbic symptoms and signs associated with antibodies against neuronal cell-surface antigens or intracellular antigens. Some cases are known to be associated with anti-channel or anti-receptor-related molecule antibodies. Whether these cases are paraneoplastic depends on the kinds of antigens that the antibodies are produced against. Other cases due to well-characterized onco-neural antibodies are almost always paraneoplastic and are generally resistant to anti-tumor therapy and/or immunotherapy. An exception is anti-Ma2 antibody-positive encephalitis associated with a testicular tumor. Antibodies for intracellular antigens are considered not to be pathogenic. Rather, the T-cell response is thought to be responsible. These antibodies are useful markers for the diagnosis of paraneoplastic disorders and in the search for underlying cancer, as neurological symptoms often precede tumor diagnosis. There is a relationship among onco-neural antibodies, clinical features, tumor types, and response to immunotherapy. Here we describe the characteristics of autoimmune encephalitis cases with antibodies against different intracellular antigens, such as Hu, Ma2, CRMP5, or amphiphysin.