Scleroderma lung: pathogenesis, evaluation and current therapy

The lungs are frequently involved in systemic sclerosis ('scleroderma'), a rare, disabling disease of unknown origin, characterised by skin thickening and Raynaud's phenomenon. The pathogenesis of scleroderma is complex, but signs and symptoms of excessive fibrosis, vasculopathy and inflammation are almost universally present. Dyspnoea in scleroderma patients can be due to chest wall tightening from skin thickening, pleural disease, cardiac involvement, myositis of intercostal muscles, or so-called scleroderma lung disease. Scleroderma lung disease encompasses vascular (pulmonary artery hypertension) or interstitial lung disease, or both. A comprehensive work-up is required to delineate the underlying cause of dyspnoea in a scleroderma patient, and to establish the contribution of each component to the symptoms. This should include a 6-minute walk test, pulmonary function testing, high-resolution thoracic CT scanning, ECG, echocardiography and, if pulmonary artery hypertension is suspected, right-heart catheterisation; bronchoalveolar lavage is optional. Lung disease in scleroderma contributes significantly to excess morbidity and early mortality, especially when diffusion capacity drops below 40% and/or forced vital capacity below 50%. However, recent clinical studies have unequivocally demonstrated that scleroderma lung disease is amenable to treatment with new vasodilatory drugs that target specific pathways involved in vasoconstriction, or with cyclophosphamide for interstitial lung disease. Uncontrolled studies have suggested that these therapies also have an impact on survival, but controlled studies with a long follow-up are needed to corroborate this point.