Autoimmune necrotizing inflammatory myopathy has a special place among autoimmune muscle diseases. Recently described, this entity is diagnosed on muscle biopsy with aspects more necrosis than inflammation, a muscle deficit of varying importance, an increase of CPK level and autoantibodies directed against the HMGCR and / or SRP. Taking statins is one of the triggers most often found, but it is not the only one.
In an article published in April 2021 by a New York team, a post-viral etiology may be involved. In the case reported, a 57-year-old woman came to the emergency room in the context of a Covid-19 infection a month earlier but not serious. She mainly complained of dyspnea. The diagnostic work-up showed rhabdomyolysis with a CPK level +/- 15,000 U / l and a positive IgG serology against SARS-Cov2. Three months later, the patient presented a progressive muscle deficiency predominantly distal and the diagnosis was made on the data of muscle histology and imaging (muscle edema in the lower limbs while the HMGCR and SRP serologies always remained negative). The patient, treated with corticosteroid therapy (1 mg / kg / day) and a physiotherapy program, will recover perfectly thereafter. This observation raises the question of the causal link between SARS-Cov2 infection and autoimmune myopathy, especially in the absence of specific myositis antibodies.