Scleroderma is believed to be an immune disease in which a genetic background and an environmental stimulus get together to stimulate the immune system in an unstoppable cycle. There are two stimuli to begin the cycle.
Fibroblasts are cells that support body tissue and turn on to produce collagen.
Then the collagen turns on the immune system again. The disease also can start with the blood vessel damage, which turns on the immune system or stimulates the fibroblasts. Again, turning on the collagen, which stimulates the immune system. So there are basically two ways in which there is an increased fibroblast proliferation and release of collagen, thus further stimulation. The collagen increases in concentration and makes the skin feel hard.