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Concept
Polype hyperplasique
Résumé
A hyperplastic polyp is a type of colorectal polyp.
Most hyperplastic polyps are found in the distal colon and rectum. They have no malignant potential, which means that they are no more likely than normal tissue to eventually become a cancer.
Hyperplastic polyps on the right side of the colon do exhibit a malignant potential. This occurs through multiple mutations that affect the DNA-mismatch-repair pathways. As such DNA mutations during replication are not repaired. This leads to microsatellite instability which can eventually lead to malignant transformation in polyps on the right side of the colon.
Serrated polyposis syndrome
Serrated polyposis syndrome is a rare condition that has been defined by the World Health Organization as either:
≥5 serrated lesions/polyps proximal to the rectum, all ≥ 5 mm in size, with two lesions ≥10 mm
20 serrated lesions/polyps of any size distributed throughout the large bowel with 5 proximal to the rectum. Histopathologically, there are two main types of hyperplastic polyps, which have genetic differences, as well as different histologic structure, but no significant differences clinically. The two main types of hyperplastic polyps are microvesicular mucin-rich type and goblet cell-rich type. A mucin-poor type with eosinophilic cytoplasm, which is rare, was previously described. However, the mucin poor type is no longer considered a distinct subtype. The luminal portion has a serrated ("saw tooth") appearance formed by tufts or folds of abundant apical cytoplasm. It contains glands with star-shaped lumina. There are crypts that are elongated but straight, narrow and hyperchromatic at the base. All crypts reach to the muscularis mucosae. The basement membrane is frequently thickened. Elongated, fat crypts and little to no serration. Therefore, they may not be obvious without comparing to adjacent normal intestinal wall. They are filled with goblet cells, extending to surface, which commonly has a tufted appearance. Infrequently, the epithelium is misplacement into the submucosa.
Source officielle
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