Interstitial lung disease in systemic sclerosis

Interstitial lung disease (ILD) is a common manifestation of systemic sclerosis (SSc) and mainly encountered in patients with diffuse disease and/or anti-topoisomerase 1 antibodies. ILD develops in up to 75% of patients with SSc overall. However, SSc-ILD evolves to end-stage respiratory insufficiency in only a few patients. Initial pulmonary function tests (PFT) with measurement of carbon monoxide diffusing capacity, together with high-resolution computed tomography, allows for early diagnosis of SSc-ILD, before the occurrence of dyspnea. Unlike idiopathic ILD, SSc-ILD corresponds to non-specific interstitial pneumonia in most cases, whereas usual interstitial pneumonia is less frequently encountered. Therefore, the prognosis of SSc-ILD is better than that for idiopathic ILD. Nevertheless, ILD represents one of the two main causes of death in SSc patients. To detect SSc-ILD early, PFT must be repeated regularly, every 6 months to 1 year, depending on disease worsening. Conversely, broncho-alveolar lavage is not needed to evaluate disease activity in SSc-ILD but may be of help in diagnosing opportunistic infection. The treatment of SSc-ILD is not well established. Cyclophosphamide, which has been used for 20 years, has recently been evaluated in two prospective randomized studies that failed to demonstrate a major benefit for lung function. Open studies reported mycophenolate mofetil, azathioprine and rituximab as alternatives to cyclophosphamide. On failure of immunosuppressive agent treatment, lung transplantation can be proposed in the absence of other major organ involvement or severe gastro-esophageal reflux.