systemic sclerosis

Systemic connective tissue autoimmune disease characterised by vasculopathy, autoimmunity and fibrosis; categorised into limited SSc and diffuse SSc

Aetiology

Higher incidence in females
Peak incidence 30-50 years
Autoimmune condition due to a combination of a genetic predisposition and an environmental trigger

The disease is the result of vascular damage within the skin and organs; organ damage is usually the result of fibrosis
The exact pathogenesis is not well understood
Environmental exposures such as silica and organic solvents are thought to trigger disease in some cases
A genetic component is important in some disease subsets
Multiple immunopathological findings are seen in systemic sclerosis:
- Infiltration of skin and lung lesions with activated CD4+ and CD8+ T cells
- Increased expression of adhesion molecules
- Increased production of cytokines by T helper 1 and 2 cells
- Increased activation of B cells resulting in autoantibody production and hypergammaglobulinemia

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	Limited systemic sclerosis	Diffuse systemic sclerosis
Skin thickening	Acral	Truncal and acral
Onset of symptoms	Prolonged Raynaud's phenomenon usually occurs before the onset of skin symptoms	Skin symptoms and Raynaud's phenomenon usually occur simultaneously
Joints and tendons	Rarely involved	Tendon friction rubs and contractures
Visceral involvement	Pulmonary vasculopathy and hypertension - organ involvement tends to occur later	Inflammatory lung disease, pulmonary fibrosis, renal crises and myocardial disease - early significant organ involvement
Serum antibodies	Anticentromere (70%)	Anti-Scl-70 (70%) and anti-RNA polymerase III