Scleroderma is a group of diseases that affect connective tissue in the body. This tissue supports your skin and internal organs. Scleroderma involves tissue that gets hard or thick. It can also cause swelling or pain in the muscles and joints.Some types of scleroderma lead to hard, tight skin.cleroderma is a group of diseases that affect connective tissue in the body. This tissue supports your skin and internal organs. Scleroderma involves tissue that gets hard or thick. It can also cause swelling or pain in the muscles and joints.