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

Objective. To investigate morphological abnormalities in nerve and smooth m uscle structures of the anorectal wall underlying gastrointestinal dysfunct ion in patients with systemic sclerosis (SSc). Methods, We performed deep rectal biopsy in 3 patients with limited sclerod erma of relatively recent onset and intestinal symptoms. Results, We found ultrastructural signs of axonal degeneration and cytoskel etal abnormalities in the bundles of unmyelinated fibers. There was also fo cal degeneration of smooth muscle cells, often in association with the pres ence of partially degranulated mast cells. Many mast cells were also observ ed 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. Conclusion. Our findings indicate early involvement of the autonomic nervou s system and to a lesser extent of smooth muscle cells. We confirmed the pr esence of early vascular lesions and involvement of mast cells in the patho logical process.