Polymyositis: The Comet Tail After COVID-19

Infectious agents have been implicated in the pathogenesis of autoimmune disorders for decades. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is no exception. This became evident as the pandemic evolved. Once considered a respiratory pathogen only, SARS-CoV-2 is now linked to a variety of autoimmune rheumatic disorders such as rheumatoid arthritis, systemic lupus erythematosus, reactive arthritis, spondyloarthropathies, vasculitis, and inflammatory myopathy. Although the exact cause for muscle injury in the setting of coronavirus disease 2019 (COVID-19) is not established, autoimmune inflammatory damage is the most accepted mechanism. Moreover, SARS-CoV-2 can cause direct muscle damage and indirectly through a cytokine storm. Inflammatory polymyositis in relation to COVID-19 has seldom been reported in developing countries. Here, we report a unique case of inflammatory polymyositis in a 52-year-old lady. The patient presented with muscle weakness, generalized body aches, and fatigue occurring four months after recovering from mild COVID-19. She had muscle weakness of Medical Research Council (MRC) grade 3/5 involving the shoulders and pelvic girdle with elevated muscle enzymes. Electromyography revealed an active irritable myopathic process consistent with inflammatory polymyositis. She underwent magnetic resonance imaging-guided muscle biopsy from the right thigh which revealed findings consistent with inflammatory myopathy. She was offered prednisolone and azathioprine. After four weeks of treatment, she had a remarkable improvement in her muscle strength to MRC grade 5/5.