Autoimmune Encephalitis Associated with Anti-N-methyl-D-aspartate Receptor and Anti-Hu Antibodies Successfully Treated with Carboplatin and Etoposide for Small-cell Lung Cancer

Abstract

The coexistence of multiple autoantibodies associated with autoimmune encephalitis (AE) is rare. A 63-year-old woman developed psychosis and consciousness disorder. Her cerebrospinal fluid was positive for anti-N-methyl-D-aspartate receptor antibodies, and her serum was positive for anti-Hu antibodies. Enhanced computed tomography revealed a mass in the right pulmonary hilum. AE complicated with small-cell lung cancer was diagnosed. Immunotherapy (steroid therapy and intravenous immunoglobulin) and four courses of carboplatin-etoposide chemotherapy were required to improve her neurological symptoms. When the coexistence of multiple antibodies is detected, despite its rarity, aggressive detection and treatment of any underlying malignancy may be recommended.

Keywords: anti-Hu antibody; anti-NMDAR antibody; autoimmune encephalitis; carboplatin; etoposide; small-cell lung cancer.

Figure 1.

Brain diffusion-weighted magnetic resonance imaging (a) on admission and (b) four days later. High-signal areas were observed in the bilateral cerebral white matter and disappeared four days later without specific treatment.

Figure 2.

(a) Fluid-attenuated inversion recovery and (b) apparent diffusion coefficient magnetic resonance imaging sequence showed high-signal areas in some of the high-signal regions shown on diffusion-weighted imaging.

Figure 3.

Enhanced computed tomography of the chest. A tumor was detected in the right pulmonary hilum before (a, arrowhead) and after (b, arrowhead) four courses of chemotherapy using carboplatin and etoposide.