[Surface ultrastructure of familial gastrointestinal adenomatosis]

Fourty-one adenomas from 13 cases of familial gastrointestinal adenomatosis, with 6 samples of normal colonic mucosa, 4 well differentiated adenocarcinomas and 2 villous adenomas as control, were examined by scanning electron microscopy. The surface feature of the adenomas was classified into three types: tubular, branching and irregular, based mainly on the irregularity of the enlarged and distorted crypts. There is close relationship between surface architecture and inner histologic pattern, especially the degree of atypia. The more irregular the surface architecture, the higher the atypia in histology. Those of tubular type are mostly tubular adenomas with mild dysplasia, while the majority of branching type are villous or villous-tubular adenomas with moderate or severe dysplasia. Irregular type usually implies malignant transformation. The results suggest that the observation and evaluation of the surface structure of familial adenomatosis be of great value, as a supplementary procedure, in identifying premalignancy and early malignancy in adenoma-carcinoma sequence.