Granulomatosis-associated myositis: High prevalence of sporadic inclusion body myositis

• Published in: Neurology Vol. 94; no. 9; pp. e910 - e920
• Main Authors: Dieudonné, Yannick, Allenbach, Yves, Benveniste, Olivier, Leonard-Louis, Sarah, Hervier, Baptiste, Mariampillai, Kuberaka, Nespola, Benoit, Lannes, Béatrice, Echaniz-Laguna, Andoni, Wendling, Daniel, Von Frenckell, Christian, Poursac, Nicolas, Mortier, Emmanuel, Lavigne, Christian, Hinschberger, Olivier, Magnant, Julie, Gottenberg, Jacques-Eric, Geny, Bernard, Sibilia, Jean, Meyer, Alain
• Format: Journal Article
• Language: English
• Published: United States American Academy of Neurology 03-03-2020
• ISSN: 0028-3878; 1526-632X
• DOI: 10.1212/WNL.0000000000008863

OBJECTIVETo refine the predictive significance of muscle granuloma in patients with myositis.
METHODSA group of 23 patients with myositis and granuloma on muscle biopsy (granuloma-myositis) from 8 French and Belgian centers was analyzed and compared with (1) a group of 23 patients with myositis without identified granuloma (control-myositis) randomly sampled in each center and (2) a group of 20 patients with sporadic inclusion body myositis (sIBM) without identified granuloma (control-sIBM).
RESULTSAll but 2 granuloma-myositis patients had extramuscular involvement, including signs common in sarcoidosis that were systematically absent in the control-myositis and the control-sIBM groups. Almost half of granuloma-myositis patients matched the diagnostic criteria for sIBM. In these patients, other than the granuloma, the characteristics of the myopathy and its nonresponse to treatment were similar to the control-sIBM patients. Aside from 1 patient with myositis overlapping with systemic sclerosis, the remaining granuloma-myositis patients did not match the criteria for a well-defined myositis subtype, suggesting pure sarcoidosis. Matching criteria for sIBM was the sole feature independently associated with nonresponse to myopathy treatment in patients with granuloma-myositis.
CONCLUSIONPatients with granuloma-myositis should be carefully screened for sIBM associated with sarcoidosis in order to best tailor their care.