ABSTRACT
BackgroundTo the best of our knowledge, muscle soreness is a common manifestation for the coronavirus disease-19 (COVID-19) patients, but the mechanism of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) injury to skeletal muscle remains unclear, there has been no publication focused on muscle involvement in COVID-19 patients.Case presentationWe present the case of two Chinese men with COVID-19, whose common symptoms were fatigue and muscle soreness. They went through different treatments, patient 1, 81-year-old, eventually died of multi-organ failure, and patient 2, 53-year-old, underwent amputation of the mid-lower section of left thigh. Laboratory tests in both patients showed abnormal biochemical parameters associated with skeletal muscle injury. We obtained skeletal muscle samples from these two patients, one from postmortem biopsy of gastrocnemius muscle and the other from a resected left lower limb due to thrombosis. The pathological findings in patient 1 were mainly scattered atrophic muscles, while fiber necrosis and minor inflammation were identified in patient 2, and the mild infiltrations were confirmed by CD68 and LCA staining to be predominantly macrophages and lymphocytes.ConclusionsWe report the clinical and laboratory features together with histopathological findings in skeletal muscle tissues from two COVID-19 cases and speculate that the SARS-CoV-2 may cause skeletal muscle injury. Due to the particularity of individual differences in case reports, the background of chronic neuromuscular disease in patient 1 and a minimal compartment syndrome caused by thrombosis in patient 2 need to be excluded prior to the conclusion that the skeletal muscles have been involved in COVID-19.