TNF and peeling skin syndrome: At the level of pathogenic mechanisms, cytokines play important role in the progress of both COVID-19 and rheumatic diseases: Huang et al. revealed elevated serum level of many cytokines (including IL-1β, IL-7, IL-8, IL-10, GM-CSF, IFN-γ, TNF-α, etc.)in COVID-19 patients compared with healthy people, and these cytokines are also the pathogenic factors in many rheumatic diseases, including RA, systemic lupus erythematosus (SLE), and primary Sjögren’s syndrome (pSS) [2, 3, 16, 17].