Severe Post-Viral Polymyositis after COVID-19 in Childhood: A Case Report and Literature Review

• Published in: Children (Basel) 2024-08, Vol.11 (8), p.1011
• Main Authors: Marciulynaite, Jurgita, Sileikiene, Rima, Snipaitiene, Ausra
• Format: Article
• Language: English
• Subjects: Abdomen; Anemia; Antibodies; Antigens; Autoimmunity; Case Report; Case reports; Childhood; children; Corticosteroids; COVID-19; Cyclophosphamide; Cytomegalovirus; Disease; Dysphagia; Edema; Health aspects; Illnesses; Immunotherapy; Infection; Kinases; Literature reviews; Muscle pain; myositis; Nonsteroidal anti-inflammatory drugs; Pandemics; Patients; Pediatrics; Polymyositis; post-COVID; post-viral; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Steroids; Streptococcus infections; Thrombocytopenia; Viral antibodies
• ISSN: 2227-9067; 2227-9067
• DOI: 10.3390/children11081011

Polymyositis is a rarely reported complication of COVID-19 illness, especially in children. Molecular mimicry may be a cause of hyperactivated autoimmunity, leading to various clinical manifestations, including myopathies. Symptoms vary from mild muscle weakness to severe rhabdomyolysis. We review the literature on post-COVID myositis and report a case of severe polymyositis in a 7-year-old boy, following undefined viral infection 3 weeks before the onset of muscle pain. Patient's condition deteriorated from physical activity-associated pain in the lower limbs to severe muscle weakness leading to dysphagia and mechanical ventilation. As antibodies against SARS-CoV-2 were detected and other possible conditions causing myositis were excluded, the diagnosis of post-COVID polymyositis was considered as the most likely. The patient was treated with high doses of methylprednisolone and cyclophosphamide, resulting in improvement. Although COVID-19 is becoming a seasonal disease, the infection itself and post-viral disorders, such as polymyositis, are still of great interest and require better investigation to ensure appropriate management for each individual. Our experience suggests that aggressive immunosuppressive therapy might be a solution for severe post-COVID-related diseases. This literature review is provided in addition to the case report presented at the 29th European Paediatric Rheumatology Congress; the abstract is available online in the Proceedings of the 29th European Paediatric Rheumatology Congress.