Small colorectal polyps: histopathology and clinical significance

The development of colorectal adenomas and carcinoma involves both environmental and genetic factors. Wide variations among populations have been observed in the prevalence of adenoma. Investigations of the small colorectal polyps have been divergent. The distribution of these small polyps remains in controversy. The histology, clinical significance, and optimal treatment of such lesions have yet to be defined. The aim of the present prospective study is to ascertain the importance of small colorectal polyps in the Taiwanese and to define their histopathological nature, spatial distribution, and clinical significance.

We prospectively evaluated all patients referred for colonoscopy for miscellaneous indications. All raised lesions encountered during the procedure were removed or biopsied. Each polyp was estimated in situ by visual comparison with the known width of a standard fully opened biopsy forceps. Small colorectal polyps were defined as those measuring 8 mm or less in diameter. Histopathology of these small polyps were reviewed and correlated clinically.

124 patients were found to have 159 small colorectal polyps. There were 88 men (71%) and 36 women (29%). The mean ages were 60.2 yr for men and 50.8 yr for women. Solitary polyps were present in 68.5% of patients while 26.6% had two polyps and 4.9% had between 3 and 10 polyps; 60.4% of the small polyps were neoplastic, while 39.6% including 23.9% hyperplastic polyps were nonneoplastic; 50.3% of the small polyps were located in the rectosigmoid. Tubular adenomas accounted for 90.6% of the small neoplastic polyps. The neoplastic polyps predominated in each colorectal segment. The proportion of small neoplastic polyps was higher in older patients; 2.8% of the small adenomas showed moderate dysplasia. Severe dysplasia was noted in only one polyp. No malignancy was observed. The chi-square test with Yates' correction was used for statistical analysis.

These findings reveal that a large share of the small colorectal polyps are neoplastic and therefore at risk to progress to carcinoma. The location of small polyps distributed at the rectosigmoid or the proximal colon was of no significance (p > 0.2) for the proportion of neoplastic polyps. The older patients probably have higher risk because of their higher proportions of small neoplastic polyps. All polyps should be removed when encountered during colonoscopy due to the high prevalence of adenomas among small colorectal polyps.