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Anti-aminoacyl-tRNA synthetase-related myositis and dermatomyositis: clues for differential diagnosis on muscle biopsy

Authors
  • Cerbelli, Bruna1
  • Pisano, Annalinda1
  • Colafrancesco, Serena2
  • Pignataro, Maria Gemma1
  • Biffoni, Marco3
  • Berni, Silvia1
  • De Luca, Antonia1
  • Riccieri, Valeria2
  • Priori, Roberta2
  • Valesini, Guido2
  • d’Amati, Giulia1
  • Giordano, Carla1
  • 1 Sapienza University of Rome, Department of Radiological, Oncological and Pathological Sciences, Policlinico Umberto I, Viale Regina Elena 324, Rome, 00161, Italy , Rome (Italy)
  • 2 Sapienza University of Rome, Department of Internal Medicine and Medical Specialties, Rheumatology Unit, Rome, 00161, Italy , Rome (Italy)
  • 3 Sapienza University of Rome, Department of Surgical Science, Rome, 00161, Italy , Rome (Italy)
Type
Published Article
Journal
Virchows Archiv
Publisher
Springer Berlin Heidelberg
Publication Date
Nov 16, 2017
Volume
472
Issue
3
Pages
477–487
Identifiers
DOI: 10.1007/s00428-017-2269-x
Source
Springer Nature
Keywords
License
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Abstract

Anti-synthetase syndrome is an autoimmune disease characterized by autoantibodies toward amino acyl-tRNA synthetases (ARS), anti-Jo 1 being the most commonly detected. Muscle damage develops in up to 90% of ARS-positive patients, characterized by a necrotizing myositis restricted to the perifascicular region. This topographic distribution of muscle damage may lead to a misdiagnosis of dermatomyositis (DM) at muscle biopsy. We compared morphological, immunohistochemical, and histoenzymatic features of muscle from ARS-positive patients (n = 11) with those of DM (n = 7) providing clues for their differential diagnosis. In addition, we evaluated markers of mitochondrial damage to provide a further distinction between these two entities. Necrosis occurred in the majority of ARS patients, mainly located in the perifascicular region. It was often limited to small foci of fibers, always associated with myocyte regeneration. This last often overwhelmed necrosis, representing occasionally the main finding. In DM, necrosis/regeneration was scarce while the peculiar feature was a diffuse atrophy of perifascicular fibers. These last showed decreased cytochrome c oxidase (COX) stain and mitochondrial DNA depletion, consistent with mitochondrial dysfunction. In contrast to DM, ARS displayed scattered COX-deficient fibers, not restricted to the perifascicular region. This feature occurred in up to 91% of patients, being prominent only in two.

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