Many of the major rheumatologic disorders are autoimmune in nature. Connective tissue diseases represent classical models of systemic autoimmune diseases.
In 1942, Paul Klemperer described similarities of systemic lupus erythematosus (SLE) and scleroderma and postulated that these diseases, which he called diffuse collagen diseases, share a similar etiology. In 1952, they were termed connective tissue diseases. Still later on, Sjögren's syndrome and poly-/dermatomyositis were added to the group of connective tissue diseases.