[A case of bilateral auricular chondritis with anti-glutamate receptor (GluRε2) antibody-positive non-herpetic acute limbic encephalitis].

A 62-year-old man experienced pain and swelling in both of his auricles. One and a half months later, he was referred to us because of a memory disturbance. A neurological examination revealed disorientation and recent memory impairment. Diffusion-weighted and fluid-attenuated inversion recovery magnetic resonance images showed high intensity and swelling lesions in the bilateral medial temporal regions. In cerebrospinal fluid, mononuclear cell counts and total protein concentration were increased, but a herpes polymerase chain reaction was negative. Thus, he was suspected to have non-herpetic acute limbic encephalitis (NHALE). In addition, relapsing polychondritis (RP) was suspected because of the bilateral auricular chondritis and type-II collagen antibody positivity in the serum. He was treated with high-dose steroid therapy (two cycles of intravenous methylprednisolone, 500 mg per day for 3 days), which was followed by oral steroid therapy. With these treatments, his symptoms, including the painful auricular swelling and memory disturbance, gradually improved. This case exhibited anti-glutamate receptor (GluRε2) antibody positivity in both serum and cerebrospinal fluid, but anti-N-methyl-D-aspartate glutamate receptor antibody (NR1 + NR2) by cell-based assay negative in cerebrospinal fluid. Although a vascular mechanism of NHALE that is associated with RP has been suggested in the literature, this autoantibody might have induced NHALE as the mechanism of neuronal damage to target neuron in our case. More studies on the pathogenesis of NHALE that is associated with RP are needed.