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Systemic sclerosis (SSc) is a generalized disorder of small arteries, microvessels and connective tissue, characterized by fibrosis and vascular obliteration in the skin and organs, particularly the lungs, heart, and digestive tract. There are two main subsets of SSc: diffuse cutaneous SSc (dcSSc) and limited cutaneous SSc (lcSSc) (see these terms). A third subset of SSc has also been observed, called limited Systemic Sclerosis (lSSc) or systemic sclerosis sine scleroderma (see these terms).
The prevalence is estimated at about 1/6,500 adults. Women are predominantly affected (F/M sex ratio around 4:1).
The disease usually manifests between 40 and 50 years of age. Raynaud's phenomenon is often the first sign of the disease. The other signs usually appear a few months later in the diffuse cutaneous subset and some years later in the limited cutaneous subset. In the limited cutaneous subset, skin involvement is limited to the hands, face, feet and forearms while in the diffuse subset it rapidly becomes generalized. Esophageal dysmotility is common and provokes gastroesophageal reflux and sometimes dysphagia. Life-threatening complications can occur such as pulmonary fibrosis and, less frequently, pulmonary arterial hypertension. The limited SSc patients have no skin involvement but only Raynaud's phenomenon, and are at risk of organ involvement.
The exact cause of SSc is unknown. The disease originates from an autoimmune reaction which leads to overproduction of collagen. In some cases, SSc is associated with exposure to chemicals (including silica, solvents and hydrocarbons).
Diagnosis is based on typical clinical manifestations and on evidence of specific microangiopathy with giant loops on capillaroscopy. Blood tests show typical antinuclear autoantibodies. The extent of the disease should be evaluated by computed tomography (CT), electrocardiogram, echocardiography, radiography of the hands and esophageal and gastric fibroscopy if needed.
Differential diagnoses include Sharp syndrome, systemic lupus erythematosus, antiphospholipid syndrome, polyarteritis nodosa, polymyositis, and rheumatoid arthritis (see these terms).
Management and treatment
Management is mostly symptomatic. Raynaud's phenomenon can be treated with calcium channel blockers. Proton pomp inhibitors are given for gastric reflux. Low doses of corticosteroids with immunosuppressive agents are needed in cases with recent and severe cutaneous involvement or in progressive lung fibrosis. Pulmonary vasodilators are given in case of pulmonary arterial hypertension. Patients require regular clinical follow-up with early pulmonary function tests and echocardiography.
The prognosis depends on the subset of SSc. The prognosis for limited cutaneous SSc is relatively good (10-year survival rate of 80-90%). However, pulmonary arterial hypertension, which occurs in about 10% of cases, and severe lung fibrosis, may lead to a more severe prognosis. The prognosis for diffuse cutaneous SSc is more severe (10-year survival rate of 60-80%) because of the higher risk of life-threatening complications: renal crisis, severe digestive involvement, severe lung fibrosis, and, sometimes, severe heart involvement and pulmonary arterial hypertension.