Background: Atrophy of the smooth muscle layers of the muscularis propria characterises oesophageal involvement in systemic sclerosis (scleroderma). The aetiology of this atrophy and of the resultant oesophageal dysfunction is unknown. Objectives: To examine oesophageal tissue for evidence of fibrosis, vascular disease, inflammatory reactions and neural abnormalities to determine the possible causes of this disease process. Methods: A case-control survey was conducted using oesophageal tissue from 74 scleroderma cases and 74 age, race and sex-matched controls from our autopsy files. Histological evidence of oesophageal muscle atrophy was correlated with the degree of vascular changes, inflammatory infiltration, fibrosis, abnormalities of the myenteric plexus and reduction of interstitial cells of Cajal (ICC) using a predesigned semiquantitative descriptive method. Results: Smooth-muscle atrophy was found in 94% of scleroderma cases, and in 5% of controls (p<0.001). Atrophy was evident in the circular smooth muscle in 93% of cases, and in the longitudinal smooth muscle in 66% of cases. Intimai proliferation of arterioles was found in 38% of cases and in 5% of controls (p<0.001), but was not associated with smooth-muscle atrophy (p=0.29). Despite these vascular changes, there was no evidence of compromised perfusion, such as findings suggestive of acute ischaemic necroses. Minimal cellular infiltrates were seen in the myenteric plexus in 82% of cases and in 92% of controls (p=0.091). ICC were found in fewer numbers in areas of atrophic smooth muscle compared with adjacent normal smooth muscle in selected scleroderma cases. Conclusion: The pathological findings of oesophageal lesions in scleroderma seem inconsistent with either an ischaemic or an inflammatory process. The loss of circular and longitudinal smooth muscle in the distal scleroderma oesophagus may represent loss of normal neural function followed by secondary tissue atrophy, or may be a primary smooth muscle lesion.
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