The CREST syndrome is a well-recognized variant of progressive systemic sclerosis. The PSS-CREST differs from PSS-DS by the limitation of skin thickening to the extremities (in most cases the distal-most portions), a protracted course, and the relative sparing of internal organs. No detailed information is available concerning pulmonary parenchymal involvement in PSS-CREST. One form of pulmonary involvement has been reported by Salemi et al, who noted ten patients with PSS-CREST who had moderate pulmonary hypertension. Complete pulmonary function tests were not reported. None of their patients had significant parenchymal disease by chest roentgenogram in contrast to the many reports of pulmonary parenchymal fibrosis seen in patients with PSS. The present study investigated the prevalence of pulmonary dysfunction in PSS-CREST and further characterized the abnormalities found.
The patients were classified using simple schemes (see Methods) relying on spirometry for several reasons. Values obtained from spirometry (FVC, FEVJ FVC, FEF25-75) are better standardized, have well-defined ranges of normality, and were uniformly performed in the patient population, precluding any selection bias. The FVC was used as the hallmark of restrictive lung disease, and the FEV^FVC as the marker of airflow obstruction. The 1/D and 1/VC 0 were not measured in this retrospective analysis. The Deo was used primarily as a marker of capillary surface area since studies have shown that at rest, values for this test correlate most closely with capillary surface area and pulmonary capillary blood volume.
Pulmonary Function Testing—PSS-CREST
Pulmonary function data for the PSS-CREST group are presented in Table 1. Mean values for the group as a whole for FVC, FEVb FEV/FVC, FRC, and TLC were normal. The mean Deo was mildly decreased.
When the patients were separated into the five previously defined physiologic groups, normal results were found in 25 (28 percent), restrictive abnormalities in 20 (23 percent), obstructive abnormalities in 14 (16 percent), isolated reduction in Deo in 23 (26 percent), and an isolated reduction in FEF25-75 in six (7 percent). The mean values ± SD of the pulmonary function results are presented in Table 2.
Progressive systemic sclerosis (PSS) is often divided into two clinical categories; PSS with difiuse scleroderma and the CREST syndrome variant of PSS, which occur with equal frequency. In the former, there is widespread involvement of the skin including trunk as well as both distal and proximal portions of the extremities, and a tendency to the relatively early development, and often rapid progression, of visceral disease affecting the gastrointestinal tract, heart, lung, and kidneys. The cardinal features of the CREST syndrome variant (PSS-CREST) include subcutaneous calcinosis (C), Raynaud’s phenomenon (R), esophageal dysmotility (E), sclerodactyly (S), and telangiectasia (T). Its clinical course is usually indolent, and many years may elapse before the appearance of visceral disease.