The combination of magnifying colonoscopy and dye spraying is helpful in determining the nature of colonic lesions as non-neoplastic, adenomas, or invasive carcinomas. Therefore it may be possible to determine, at the time of colonoscopy, which lesions require no treatment, which can be removed endoscopically, and which should be removed by surgery.
Background-Hyperplastic polyps are common benign colorectal polyps, and are thought to have little association with malignant tumours in the colorectum. However, several reports suggest that some hyperplastic polyps may develop into colorectal neoplasms. Aim-To clarify genetic alterations in colorectal hyperplastic polyps. Methods-Twenty eight colorectal polyps having serrated components were resected from patients endoscopically. The K-ras gene mutations in codons 12 and 13 were analysed by PCR-RFLP. Intranuclear p53 protein was immunostained by the avidin-biotin complex method. Results-A mutation of the K-ras gene was detected in nine (47%) of 19 hyperplastic polyps, and five (56%) of nine adenomas. p53 protein nuclear accumulation was detected immunohistochemically in two (22%) of nine adenomas, but not in any of the 19 hyperplastic polyps. Conclusion-Some hyperplastic polyps may be true neoplastic lesions, and could be precursors of malignant neoplasia.
The reason for the decreased fluorescence in diseased tissues appears to be a decrease in collagen fluorescence due to the screening effect of mucosal thickening or replacement of submucosa by cancer cells.
Small advanced cancers (less than 10 mm in size) have rarely been described in the literature, mainly due to their difficult endoscopic diagnosis. A total of 5120 colonoscopic examinations were performed at the National Cancer Center Hospital East; three cases (0.05%) of small advanced cancer were found. The indigo carmine dye spraying technique with magnifying endoscopy was used for diagnosis. All cases were flat and depressed lesions (8, 9 and 9 mm in size respectively) with V type pit pattern at the magnifying observation. Histology showed three cancers with invasion to the proper muscle layer and two cases of lymph node metastasis. K-ras point mutation was negative in all cases, while p53 stained in two out of the three cases (one diffuse and one focal). It is concluded that small advanced colorectal adenocarcinomas are a reality. Our data on their macroscopic appearance and histology confirm their high malignant potential.
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