Anti-EJ, anti-MDA5 double-positive chronic clinically amyopathic dermatomyositis: a case report

摘要

Anti-aminoacyl-tRNA synthetase (ARS) and antimelanomadifferentiation-associated gene 5 (MDA5)antibodies are known to be myositis-specific autoantibodies(MSAs). These antibodies are closely associatedwith interstitial lung disease (ILD) [1, 2]. These MSAsare, in general, mutually exclusive; therefore, coexistenceof these antibodies is rare.In 2016, a 53-year-old Japanese woman was admittedto our department with a dry cough and dyspnoea,worsening over 2 months. She had been diagnosed withclinically amyopathic DM associated with ILD in 2001.Initially, she had heliotrope rash, facial erythema,Gottron papules with some shallow ulcers, mechanic’shands and periungual erythema. Skin biopsy from theGottron papule showed interface dermatitis. She had RPbut no arthritis. Although muscle pain or weakness wasnot present, there was a slight elevation of creatine kinase(range of 200–250 U/l) on the blood test and myogenicchanges on electromyographic examination inbiceps and tibialis anterior (muscle MRI and biopsywere not performed). Initial treatment with prednisolone30mg/day (0.8mg/kg/day) and ciclosporin improved theskin lesions and ILD. She later experienced three episodesof ILD flare-up (in 2002, 2005 and 2007), but increasingprednisolone from maintenance dose of 7-8mg/day to30-55mg/day (0.8-1.0mg/kg/day) in combination witheither ciclosporin or i.v. CYC therapy (500mg/m2monthly) was successful in inducing remission of ILD eachtime. The disease was well controlled with prednisolone7–8mg/day and tacrolimus 4mg/day for 8 years. Antiglycyl-tRNA synthetase (anti-EJ) antibody was detected byRNA immunoprecipitation in 2001 and 2005.