title: The Prevalence of Individual Histopathologic Features  Varies according to Autoantibody Status in Muscle  Biopsies from Patients with Dermatomyositis.
abstract: OBJECTIVE
  Individual dermatomyositis (DM)-associated autoantibodies are associated with distinct clinical phenotypes. This study was undertaken to explore the association of these autoantibodies with specific muscle biopsy features.
  
  
  METHODS
  DM subjects with a muscle biopsy reviewed at Johns Hopkins had sera screened for autoantibodies recognizing Mi-2, transcriptional intermediary factor 1-γ (TIF1-γ), NXP2, MDA5, Ro52, PM-Scl, and Jo1. We also included anti-Jo1–positive patients with polymyositis (PM) who had a biopsy read at Johns Hopkins. Analyzed histological features included perifascicular atrophy, perivascular inflammation, mitochondrial dysfunction, primary inflammation, and myofiber necrosis. Duration of disease, biopsy location, and treatment at biopsy were also analyzed.
  
  
  RESULTS
  We studied 91 DM and 7 anti-Jo1–positive patients with PM. In univariate analyses, TIF1-γ+ patients had more mitochondrial dysfunction (47% vs 18%; p = 0.05), NXP2+ patients had less primary inflammation (0% vs 28%; p = 0.01), Mi-2+ patients had more primary inflammation (50% vs 19%; p = 0.03), and PM-Scl+ patients had more primary inflammation (67% vs 18%; p = 0.004) than those who were negative for each autoantibody. Although reliability was limited because of small sample numbers, multivariate analysis confirmed that TIF1-γ+ patients had more mitochondrial dysfunction [prevalence ratio (PR) 2.6, 95% CI 1.0–6.5, p = 0.05] and PM-Scl+ patients had more primary inflammation (PR 5.2, 95% CI 2.0–13.4; p = 0.001) independent of disease duration at biopsy, biopsy site, and treatment at biopsy. No differences in muscle biopsy features were noted between anti-Jo1–positive patients diagnosed with DM and PM.
  
  
  CONCLUSIONS
  The prevalence of different histological features varies according to autoantibody status in DM. Muscle biopsy features are similar in anti-Jo1 patients with and without a rash.
authors.forename: Iago
authors.initials: I
authors.lastname: Pinal-Fernandez
authors.forename: Livia A
authors.initials: LA
authors.lastname: Casciola-Rosen
authors.forename: Lisa
authors.initials: L
authors.lastname: Christopher-Stine
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Corse
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Mammen
mesh_terms: D000328:Adult; D001323:Autoantibodies / Q000097:blood*; D001706:Biopsy; D003882:Dermatomyositis / Q000097:blood / Q000276:immunology / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology*; D017285:Polymyositis / Q000097:blood / Q000276:immunology / Q000473:pathology*
chemical_list: D001323:Autoantibodies