title: Caspr2 antibody limbic encephalitis is associated with Hashimoto thyroiditis and thymoma.
abstract: BACKGROUND
  Contactin-associated protein 2 (Caspr2) antibody is a neuronal surface antibody (NSAb) capable of causing disorders involving central and peripheral nervous systems (PNS). Thymoma can be found in patients with Caspr2 antibodies and is most frequently associated with PNS symptoms. Myasthenia gravis can be found in these patients, but Hashimoto thyroiditis (HT) has not been reported.
  
  
  METHODS
  A 76-year-old woman presented with sub-acute-onset changes in mental status. Further investigations revealed thymoma and HT. The presence of NSAb was tested by immunofluorescence on human embryonic kidney-293 cells. Treatment included corticosteroids, azathioprine, thyroxine, plasmapheresis, and thymectomy.
  
  
  RESULTS
  Caspr2 antibody was positive in serum but absent in CSF. Brain magnetic resonance imaging (MRI) showed diffuse cortical atrophy, but did not change significantly after treatments. Brain positron emission tomography (PET) revealed diffuse hypometabolism over the cerebral cortex. The patient's mental status only partially improved.
  
  
  CONCLUSIONS
  In Caspr2 antibody-associated syndromes, thymoma can occur in patients presenting only with LE, and HT can be an accompanying disease. Brain MRI and PET may not show specific lesions in limbic area. Patients with Caspr2 antibodies and thymoma may not have good prognosis.
authors.affiliation: Section of Epilepsy, Department of Neurology, Chang Gung Memorial Hospital at Linkou Medical Center and Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Chih-Hong
authors.initials: CH
authors.lastname: Lee
authors.affiliation: Division of Pediatric Neurology, Chang Gung University, College of Medicine, Taoyuan, Taiwan; Chang Gung Children's Hospital Study Group for Children with Encephalitis/Encephalopathy Related Status Epilepticus and Epilepsy (CHEESE), Taiwan.
authors.forename: Jainn-Jim
authors.initials: JJ
authors.lastname: Lin
authors.affiliation: Molecular Imaging Center and Department of Nuclear Medicine, Chang Gung Memorial Hospital at Linkou Medical Center, Taoyuan, Taiwan; Healthy Aging Research Center and Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taiwan.
authors.forename: Kun-Ju
authors.initials: KJ
authors.lastname: Lin
authors.affiliation: Section of Epilepsy, Department of Neurology, Chang Gung Memorial Hospital at Linkou Medical Center and Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Bao-Luen
authors.initials: BL
authors.lastname: Chang
authors.affiliation: Section of Epilepsy, Department of Neurology, Chang Gung Memorial Hospital at Linkou Medical Center and Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Hsiang-Yao
authors.initials: HY
authors.lastname: Hsieh
authors.affiliation: Division of Thoracic Surgery, Department of Surgery, Chang Gung Memorial Hospital at Linkou Medical Center, Taoyuan, Taiwan.
authors.forename: Wei-Hsun
authors.initials: WH
authors.lastname: Chen
authors.affiliation: Division of Pediatric Neurology, Chang Gung University, College of Medicine, Taoyuan, Taiwan; Chang Gung Children's Hospital Study Group for Children with Encephalitis/Encephalopathy Related Status Epilepticus and Epilepsy (CHEESE), Taiwan; Graduate Institute of Clinical Medical Sciences, Chang Gung University, College of Medicine, Taoyuan, Taiwan.
authors.forename: Kuang-Lin
authors.initials: KL
authors.lastname: Lin
authors.affiliation: Section of Epilepsy, Department of Neurology, Chang Gung Memorial Hospital at Linkou Medical Center and Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Hon-Chung
authors.initials: HC
authors.lastname: Fung
authors.affiliation: Section of Epilepsy, Department of Neurology, Chang Gung Memorial Hospital at Linkou Medical Center and Chang Gung University College of Medicine, Taoyuan, Taiwan. Electronic address: lysander@cgmh.org.tw.
authors.forename: Tony
authors.initials: T
authors.lastname: Wu
mesh_terms: D000368:Aged; D034961:Antigens, Nuclear / Q000276:immunology; D001323:Autoantibodies / Q000097:blood* / Q000134:cerebrospinal fluid*; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology; D016022:Case-Control Studies; D002461:Cell Line, Transformed; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D057809:HEK293 Cells; D050031:Hashimoto Disease / Q000150:complications*; D006801:Humans; D020363:Limbic Encephalitis / Q000150:complications* / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000378:metabolism*; D008279:Magnetic Resonance Imaging; D008565:Membrane Proteins / Q000276:immunology*; D009419:Nerve Tissue Proteins / Q000276:immunology*; D049268:Positron-Emission Tomography; D013945:Thymoma / Q000150:complications*; D013974:Thyroxine; D013997:Time Factors; D014162:Transfection
chemical_list: D034961:Antigens, Nuclear; D001323:Autoantibodies; C403049:CNTNAP2 protein, human; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D019788:Fluorodeoxyglucose F18; D013974:Thyroxine
keywords: Autoimmune encephalitis; Caspr2; Hashimoto thyroiditis; Neuronal surface antibodies; Thymoma; VGKC