What chronic condition leads to the hardening of tissues and organs due to excess collagen?

Scleroderma is a chronic autoimmune condition characterized by the hardening and tightening of the skin and connective tissues due to an overproduction of collagen. In scleroderma, the excess collagen leads to fibrosis, which can affect not only the skin but also various organs such as the lungs, heart, and kidneys, ultimately impacting their function. This condition results in the thickening and stiffening of these tissues, causing a range of symptoms including difficulty in movement, pain, and other systemic complications.

While fibrosis is a key process in scleroderma, it's essential to recognize that fibrosis itself can occur as a result of various conditions, not just scleroderma. Atherosclerosis, on the other hand, involves the accumulation of lipids and other substances in arterial walls and is not primarily related to collagen deposition. Myositis is an inflammation of muscle tissue which does not involve the collagen buildup characteristic of scleroderma. Thus, scleroderma is distinctly defined by its collagen-related changes, making it the correct answer to the question.