Autoimmune Encephalitis as an Extra-articular Manifestation of Rheumatoid Arthritis: A Case Report.

Autoimmune encephalitis (AE) is an immune-mediated encephalitis characterized by the subacute onset of memory deficits, altered mental status, or psychiatric symptoms. Limbic encephalitis associated with rheumatoid arthritis (RA) has not been reported yet. A 57-year-old man presented with the subacute onset of headache, depression, and anorexia 7 months before the onset of RA. Brain magnetic resonance imaging showed symmetric parenchymal lesions involving the medial temporal lobes. He was diagnosed with RA and AE, but no autoantibodies to neuronal intracellular or cell-surface antigens were identified in either the serum or cerebrospinal fluid. His symptoms improved with immunotherapy. AE can develop as an extra-articular manifestation of RA.