Autonomic nervous system and smooth muscle cell involvement in systemic sclerosis: ultrastructural study of 3 cases.

Abstract

To investigate morphological abnormalities in nerve and smooth muscle structures of the anorectal wall underlying gastrointestinal dysfunction in patients with systemic sclerosis (SSc). We performed deep rectal biopsy in 3 patients with limited scleroderma of relatively recent onset and intestinal symptoms. We found ultrastructural signs of axonal degeneration and cytoskeletal abnormalities in the bundles of unmyelinated fibers. There was also focal degeneration of smooth muscle cells, often in association with the presence of partially degranulated mast cells. Many mast cells were also observed in close relation to nerve fibers and vessels. The enteric vessels often showed basal lamina reduplication and hypertrophied endothelial cells with obliterated lumen. No significant fibrosis was found. Our findings indicate early involvement of the autonomic nervous system and to a lesser extent of smooth muscle cells. We confirmed the presence of early vascular lesions and involvement of mast cells in the pathological process.