Abstract
The surface ultrastructure of both experimental and clinical colorectal polypoid lesions was observed using a dissecting microscope(DM) and a scanning electron microscope (SEM), and studied in relation to the respective histological findings, Ninety-four rat colonic lesions experimentally induced by N-methyl-N'-nitro-N-nitrosoguanidine and 36 clincally obtained lesions were examined under various magnifications, from 7x to 40x, with the DM after -spraying with 0.2% methylene blue, and 68 specimens were examined under magnifications, ranging from 50x to 5000x, with the SEM. The surface structures were classified into 5 types: circular, tubular, mixed, sulcate and irregular. The surface structure and histology of the 94 experimental specimens were as follows ; seven circular-type lesions were all hyperplastic polyps, and among 25 lubular-type lesions, 18 (72%) showed mild atypia. There were no circular or tubular-type lesions among cases of severe atypia or invasive cancer. Twenty-two irregular, 5 mixed and 7 sulcate-type lesions showed severe atypia or invasive cancer. Of the 36 clinical lesions, 5 tubular-type lesions all showed mild atypia. Among 16 sulcate-type lesions, 11 (68%) showed moderate atypia. One sulcate-type lesion and 2 irregular-type lesions were malignant. It is speculated that the more the surface structure of a lesion becones complicated, the more advanced its state of atypia.
