The dilated duodenum may be slow to empty, and the grossly dilated, atonic organ may produce a sump effect.The small intestine can also become involved, leading to bacterial overgrowth and malabsorption of bile salts, fats, carbohydrates, proteins, and vitamins. The colon can be involved, and can cause pseudo-obstruction or ischemic colitis.Rarer complications include pneumatosis cystoides intestinalis, or gas pockets in the bowel wall, wide-mouthed diverticula in the colon and esophagus, and liver fibrosis. Patients with severe gastrointestinal involvement can become profoundly malnourished.Scleroderma may also be associated with gastric antral vascular ectasia, also known as "watermelon stomach". This is a condition in which atypical blood vessels proliferate, usually in a radially symmetric pattern around the pylorus of the stomach. It can be a cause of upper gastrointestinal bleeding or iron-deficiency anemia in patients with scleroderma. Kidneys
Kidney involvement, in scleroderma, is considered a poor prognostic factor and frequently a cause of death.The most important clinical complication of scleroderma involving the kidney is scleroderma renal crisis (SRC), the  symptoms of which are malignant hypertension (high blood pressure with evidence of acute organ damage), hyperreninemia (high renin levels), azotemia (kidney failure with accumulation of waste products in the blood), and microangiopathic hemolytic anemia (destruction of red blood cells). Apart from the high blood pressure, hematuria (blood in the urine) and proteinuria (protein loss in the urine) may be indicative of SRC.In the past, SRC was almost uniformly fatal.
Apart from TGFβ, connective tissue growth factor (CTGF) has a possible role. Indeed, a common CTGF gene polymorphism is present at an increased level in systemic sclerosis.Damage to endothelium is an early abnormality in the development of scleroderma, and this, too, seems to be due to collagen accumulation by fibroblasts, although direct alterations by cytokines, platelet adhesion, and a type II hypersensitivity reaction  similarly have been implicated. Increased endothelin and decreased vasodilation have been documented.Jimenez and Derk describe three theories about the development of scleroderma:

The abnormalities are primarily due to a physical agent, and all other changes are secondary or reactive to this direct insult. The initial event is fetomaternal cell transfer causing microchimerism, with a second summative cause (e.g. environmental) leading to the actual development of the disease. Physical causes lead to phenotypic alterations in susceptible cells (e.g. due to genetic makeup), which then effectuate DNA changes that alter the cells behavior. Diagnosis
In 1980, the American College of Rheumatology agreed on diagnostic criteria for scleroderma.Diagnosis is by clinical suspicion, presence of autoantibodies (specifically anticentromere and anti-scl70/antitopoisomerase antibodies), and occasionally by biopsy. Of the antibodies, 90% have a detectable antinuclear antibody. Anticentromere antibody is more common in the limited form (80–90%) than in the diffuse form (10%), and anti-scl70 is more common in the diffuse form (30–40%) and in African-American patients (who are more susceptible to the systemic form).Other conditions may mimic systemic sclerosis by causing hardening of the skin.