Computer-assisted 3D mapping and morphometry of dysplastic zones in endoscopically resected colonic adenomas

Three-dimensional (3D) reconstruction and morphometry of resected colonic a denomas were undertaken to extend current knowledge of clinically significa nt features such as the frequency of occurrence of cancer, and the size and spatial distribution of dysplastic zones in these tumours, Fifty endoscopi cally resected colonic adenomas were serially sectioned at intervals of 0.2 mm and the sectional images were loaded into a computer system in order to visualize the spatial distribution of dysplastic zones. These were graded into five groups according to the criteria of Morson and Dawson: normal muc osa, mild dysplasia, moderate dysplasia, severe dysplasia, and cancer. The way in which zones of different grades are distributed in a polyp was visua lized in a computer display and the volume of each dysplastic zone was esti mated by the Cavalieri principle. In five polyps, adenocarcinoma was found growing in an adenoma, In all of these, the cancer was surrounded by less d ysplastic zones, in the form of 'cancer in adenoma'. In pedunculated polyps , submucosal invasion could occur even if the volume percent of severe dysp lasia was less than 10%. In such a case, multiple biopsy specimens are advi sable. Semipedunculated polyps smaller than 200 mm(3) can also harbour subm ucosal invasion. In this study it was found that if the adenomas had been e xamined by only a single section, as many as one in five of the cases in wh ich submucosal invasion had already developed would have escaped microscopi c confirmation. To prevent such diagnostic failure, it is advisable to add a few deeper sections. Thus, 3D reconstruction and morphometry have been he lpful in establishing a better standard for the diagnostic histopathology o f colonic tumours, Copyright (C) 2000 John Whey & Sons, Ltd.