Diagnostic potential of sarcoplasmic myxovirus resistance protein A expression in subsets of dermatomyositis

A. Uruha, Y. Allenbach, J. L. Charuel, L. Musset, A. Aussy, O. Boyer, K. Mariampillai, O. Landon-Cardinal, C. Rasmussen, L. Bolko, T. Maisonobe, S. Leonard-Louis, Shigeaki Suzuki, I. Nishino, W. Stenzel, O. Benveniste

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Aims: To elucidate the diagnostic value of sarcoplasmic expression of myxovirus resistance protein A (MxA) for dermatomyositis (DM) specifically analysing different DM subforms, and to test the superiority of MxA to other markers. Methods: Immunohistochemistry for MxA and retinoic acid-inducible gene I (RIG-I) was performed on skeletal muscle samples and compared with the item presence of perifascicular atrophy (PFA) in 57 DM patients with anti-Mi-2 (n = 6), -transcription intermediary factor 1 gamma (n = 10), -nuclear matrix protein 2 (n = 13), -melanoma differentiation-associated gene 5 (MDA5) (n = 10) or -small ubiquitin-like modifier activating enzyme (n = 1) autoantibodies and with no detectable autoantibody (n = 17). Among the patients, nine suffered from cancer and 22 were juvenile-onset type. Disease controls included antisynthetase syndrome (ASS)-associated myositis (n = 30), immune-mediated necrotizing myopathy (n = 9) and inclusion body myositis (n = 5). Results: Sarcoplasmic MxA expression featured 77% sensitivity and 100% specificity for overall DM patients, while RIG-I staining and PFA reached respectively 14% and 59% sensitivity and 100% and 86% specificity. In any subset of DM, sarcoplasmic MxA expression showed higher sensitivity than RIG-I and PFA. Some anti-MDA5 antibody-positive DM samples distinctively showed a scattered staining pattern of MxA. No ASS samples had sarcoplasmic MxA expression even though six patients had DM skin rash. Conclusions: Sarcoplasmic MxA expression is more sensitive than PFA and RIG-I expression for a pathological diagnosis of DM, regardless of the autoantibody-related subgroup. In light of its high sensitivity and specificity, it may be considered a pathological hallmark of DM per se. Also, lack of MxA expression in ASS supports the idea that ASS is a distinct entity from DM.

Original languageEnglish
JournalNeuropathology and Applied Neurobiology
Publication statusAccepted/In press - 2018 Jan 1



  • autoantibody
  • dermatomyositis
  • diagnostic marker
  • muscle pathology
  • myxovirus resistance protein A
  • type 1 interferon

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology
  • Neurology
  • Clinical Neurology
  • Physiology (medical)

Cite this

Uruha, A., Allenbach, Y., Charuel, J. L., Musset, L., Aussy, A., Boyer, O., Mariampillai, K., Landon-Cardinal, O., Rasmussen, C., Bolko, L., Maisonobe, T., Leonard-Louis, S., Suzuki, S., Nishino, I., Stenzel, W., & Benveniste, O. (Accepted/In press). Diagnostic potential of sarcoplasmic myxovirus resistance protein A expression in subsets of dermatomyositis. Neuropathology and Applied Neurobiology. https://doi.org/10.1111/nan.12519