[The ultrastructure of intestinal amyloidosis]

Amyloidosis nearly always goes along with manifestations of the gastrointestinal tract. It can mimic a variety of different clinical syndromes. Pathogenetically amyloidosis leads to an organ insufficiency due to local infiltration of amyloid or to replacement of tissue with amyloid fibrils. Characteristic ultrastructure is composed of an irregular network of fibrils without any periodicity. The topographic position gives an explanation for the intestinal symptoms. Involvement of the intramural nerve system is responsible for motility disorders like diarrhoea or constipation. In case of perivasal infiltration hemorrhage and inflammatory changes can be found, as well as malabsorption syndromes, when subepithelial amyloid layers are present. Electron microscopy therefore may contribute to the pathogenetic understanding of morphological findings in regard to clinical symptoms.