Chest Imaging

Progressive systemic sclerosis

(PSS), leads to some degree of usual interstitial pneumonia (UIP) in 75% of cases. Chest radiographs may appear normal despite abnormal pulmonary function tests. The incidence of radiographically recognizable interstitial disease is probably around 25%. In addition to UIP, PSS is commonly associated with pulmonary vasculitis and pulmonary arterial hypertension.

The radiographic and HRCT findings of interstitial fibrosis in PSS are quite similar to those of idiopathic pulmonary fibrosis (IPF), with subpleural reticulation, honeycombing or ground glass opacity (Fig.1). These abnormalities have a distinct basal, posterior and peripheral predominance. Predominant ground glass opacities often correlate with the presence of inflammation; the presence of a predominantly reticular pattern on HRCT correlates closely with the presence of fibrosis on the pathological specimens.

UIP associated with progressive systemic sclerosis follows a less progressive course and has a better long-term prognosis than UIP associated with IPF. Other findings on CT in patients with PSS include diffuse pleural thickening seen in one third of cases, asymptomatic oesophageal dilatation present in 40 80% of cases, and enlarged mediastinal nodes seen in approximately 60% of cases. The presence of oesophageal dilatation may be helpful in the differential diagnosis of PSS from other diffuse interstitial lung diseases.

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Fig.1

HRCT showing peripheral subpleural fibrosis in a patient with PSS.
Progressive systemic sclerosis, Fig.1