An older term for a group of diseases affecting CONNECTIVE TISSUE. The term is inaccurate since there is no evidence that collagen is primarily involved. Fibrinoid NECROSIS and VASCULITIS are two ‘characteristics’, and AUTOIMMUNITY reactions may occur in the connective tissue. The latter affects blood vessels and causes secondary damage in the connective tissue. Such conditions are sometimes described as collagen vascular diseases, examples being RHEUMATOID ARTHRITIS, SYSTEMIC LUPUS ERYTHEMATOSUS, and SCLERODERMA.