Relationship between cutaneous and pulmonary involvement in systemic sclerosis

Pulmonary disease may shorten survival in patients affected by systemic sclerosis (SSc). However, pulmonary involvement may commonly be silent, whereas skin fibrosis is usually the clinical feature drawing most attention. We investigated the relationship between cutaneous and pulmonary involvement during SSc.

We studied 52 patients (mean age 50.2 +/- 13.7 years) affected by SSc (mean duration of disease 13.8 +/- 9.5 years). Twenty-eight had the diffuse form of the disease (dSSc) and 24 the limited form (lSSc). All patients underwent pulmonary function studies, high resolution computed tomography (HRCT) of the lungs, and complete echocardiographic examination. Pulmonary artery systolic pressure was measured by Doppler echocardiography. Pulmonary interstitial fibrosis and skin fibrosis were evaluated using a point system.

Mean percentages of predicted values of forced vital capacity and total lung capacity were significantly reduced in patients with dSSc compared to lSSc (80.0 +/- 18.9 vs 98.4 +/- 16.8%, p < 0.001; and 81.3 +/- 13.9 vs 92.1 +/- 14.2%, p < 0.01, respectively). The overall HRCT score was 6.1 +/- 4.9, with no significant differences between disease subgroups. However, a HRCT score of 10 or more was present in 10 patients with dSSc vs 2 patients with lSSc (p = 0.02). Pulmonary hypertension was present in 27 patients, 15 with lSSC and 12 with dSSc (p = NS). No significant correlation was observed between skin score and lung volumes, carbon monoxide diffusing capacity, HRCT score, or pulmonary artery systolic pressure for all patients and subgroups.

Extent and severity of cutaneous and pulmonary involvement in SSc are not directly correlated. Nevertheless, different patterns of pulmonary involvement between SSc subgroups were observed. Restrictive lung disease was more frequent in patients with dSSc, while a trend to higher prevalence of pulmonary hypertension was observed in patients with lSSc.