Jesus Loarce-Martos1, James B Lilleker2,3, Matthew Parker4, Neil McHugh5,6, Hector Chinoy7,8. 1. Rheumatology Department, Hospital Universitario Ramón y Cajal, Madrid, Spain. 2. Centre for Musculoskeletal Research, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK. 3. Manchester Centre for Clinical Neuroscience, Salford Royal NHS Foundation Trust, Salford, UK. 4. Department of Rheumatology, RPA Institute of Rheumatology and Orthopaedics, Royal Prince Alfred Hospital, Sydney, NSW, Australia. 5. Department of Pharmacy and Pharmacology, University of Bath, Bath, UK. 6. Royal National Hospital for Rheumatic Disease, Bath, UK. 7. National Institute for Health Research Manchester Musculoskeletal Biomedical Research Centre, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK. 8. Department of Rheumatology, Salford Royal NHS Foundation Trust, Salford, UK.
Abstract
OBJECTIVE: The current classification criteria for idiopathic inflammatory myopathy (IIM) retain PM as a major disease subgroup. However, evolution in the understanding of IIM has suggested that many of these patients could be better described as having an alternative diagnosis. In the present study, we apply the latest understanding of IIM subtyping to retrospectively review PM diagnoses in a large cohort of IIM patients. METHODS: Within a previously reported cohort of 255 patients from a UK tertiary myositis clinic, 37 patients classified as PM according to both the EULAR/ACR IIM criteria and expert opinion were identified. Clinical data and complementary tests were reviewed, and consensus decisions regarding final classification were reached in each case. RESULTS: Nine (9/37, 24.3%) patients remained classified as PM, 3.5% (9/255) of the original cohort; these PM patients were seronegative for myositis antibodies, responsive to immunosuppression, and in 4/7 (57.1%) patients where muscle biopsy was performed had HLA-1 upregulation and endomysial inflammatory infiltrates. Immune-mediated necrotizing myopathy (5/37, 13.5%) and connective tissue disease overlap myositis (7/37, 19%) were the main alternative diagnoses. The remaining patients were diagnosed as: unspecified myopathy (6/37, 16%), dermatomyositis (2/37, 5%), cancer-associated myopathy (3/37, 8.1%), and non-inflammatory myopathy (1/37, 3%, myofibrillar myopathy). Four patients (4/37, 10%) had insufficient data available to confidently reclassify. CONCLUSION: Our study confirms that PM can now be considered a rare IIM subgroup. A thorough examination, complete myositis autoantibody panel, and careful interpretation of the biopsy results is recommended to confirm the correct IIM sub-type.
OBJECTIVE: The current classification criteria for idiopathic inflammatory myopathy (IIM) retain PM as a major disease subgroup. However, evolution in the understanding of IIM has suggested that many of these patients could be better described as having an alternative diagnosis. In the present study, we apply the latest understanding of IIM subtyping to retrospectively review PM diagnoses in a large cohort of IIM patients. METHODS: Within a previously reported cohort of 255 patients from a UK tertiary myositis clinic, 37 patients classified as PM according to both the EULAR/ACR IIM criteria and expert opinion were identified. Clinical data and complementary tests were reviewed, and consensus decisions regarding final classification were reached in each case. RESULTS: Nine (9/37, 24.3%) patients remained classified as PM, 3.5% (9/255) of the original cohort; these PM patients were seronegative for myositis antibodies, responsive to immunosuppression, and in 4/7 (57.1%) patients where muscle biopsy was performed had HLA-1 upregulation and endomysial inflammatory infiltrates. Immune-mediated necrotizing myopathy (5/37, 13.5%) and connective tissue disease overlap myositis (7/37, 19%) were the main alternative diagnoses. The remaining patients were diagnosed as: unspecifiedmyopathy (6/37, 16%), dermatomyositis (2/37, 5%), cancer-associated myopathy (3/37, 8.1%), and non-inflammatory myopathy (1/37, 3%, myofibrillar myopathy). Four patients (4/37, 10%) had insufficient data available to confidently reclassify. CONCLUSION: Our study confirms that PM can now be considered a rare IIM subgroup. A thorough examination, complete myositis autoantibody panel, and careful interpretation of the biopsy results is recommended to confirm the correct IIM sub-type.
Authors: Ingrid E Lundberg; Manabu Fujimoto; Jiri Vencovsky; Rohit Aggarwal; Marie Holmqvist; Lisa Christopher-Stine; Andrew L Mammen; Frederick W Miller Journal: Nat Rev Dis Primers Date: 2021-12-02 Impact factor: 52.329
Authors: Alexander G S Oldroyd; Andrew B Allard; Jeffrey P Callen; Hector Chinoy; Lorinda Chung; David Fiorentino; Michael D George; Patrick Gordon; Kate Kolstad; Drew J B Kurtzman; Pedro M Machado; Neil J McHugh; Anna Postolova; Albert Selva-O'Callaghan; Jens Schmidt; Sarah Tansley; Ruth Ann Vleugels; Victoria P Werth; Rohit Aggarwal Journal: Rheumatology (Oxford) Date: 2021-06-18 Impact factor: 7.580