Ultrastructure of the small intestinal mucosa in progressive systemic sclerosis (PSS).

The present study deals with ultrastructural changes of jejunal absorptive epithelium in mucosal biopsy specimens from eleven patients with progressive systemic sclerosis (PSS). Epithelial cells showed cytoplasmic condensations with cholesterol clefts and fat droplets. Intercellular spaces of the epithelium were dilated with deposits of fat droplets, while tight junctions and villi preserved their normal structures. Goblet cells and entero-endocrine cells showed no changes. In the lamina propria, fat droplets were observed as well. Vessels were strongly dilated and in 2 patients contained conglomerates of thrombocytes. Perivascular cell infiltrates consisted of lymphocytes, macrophages and mast cells, while plasma cells were scarcely seen; in 2 patients, plasma cells were abundant. Collagen fibrils, elastic fibres, and nerves showed no definite changes. The findings of epithelial cell degeneration and fat droplet deposits indicate dysfunction of jejunal absorptive epithelial cells in PSS.