Skin disease: a cardinal feature of systemic sclerosis

Despite the heterogeneity of SSc, almost all patients have skin involvement. As such, skin manifestations are critical in the initial diagnosis of SSc and in the subsequent sub-classification into the different subsets of disease. The two principal subsets are lcSSc and dcSSc. The main difference between these two subsets is the speed of disease progression and the extent and severity of skin and visceral involvement; lcSSc has an insidious onset with skin involvement confined largely to the face and extremities. Whilst vascular manifestations of SSc such as pulmonary arterial hypertension are typically more common in lcSSc, patients in both subsets can develop ischaemic digital ulcers. In dcSSc, disease progression is very rapid, with skin thickening extending beyond the extremities and earlier, more widespread internal organ involvement. DcSSc is generally considered to be the more severe subset of the disease. Skin scores in SSc correlate inversely with survival and are considered a valuable marker of disease severity. Skin involvement is easily detectable and, using the modified Rodnan skin score, the degree of skin fibrosis can be quantified. As well as general management measures, a number of targeted therapies are commonly used for treatment of cutaneous manifestations of SSc. These include the intravenous prostanoid iloprost and the dual endothelin receptor antagonist bosentan, which is approved in Europe for the prevention of new digital ulcers.