Insights into the Cellular Basis of Skin Inflammation in Systemic Autoimmune Rheumatic Diseases from Single-Cell technologies

Cutaneous inflammation is a common feature of several systemic autoimmune rheumatic diseases (SARDs) including systemic lupus erythematosus (SLE), undifferentiated connective tissue disease (UCTD), mixed connective tissue disease (MCTD) and dermatomyositis (DM) but is less common in other SARDs such as primary Sjögren's syndrome (pSS). It is important to understand whether the pathophysiological processes underlying skin inflammation are different or shared between SARDs to develop targeted therapies. This review will discuss commonalities and differences between inflammatory skin disease in SARDs focusing on histopathology and describe newer insights obtained from single-cell technologies.