[Incidence of malignancy in millimetric polyps]

This paper is based on the analysis of 178 polyps of 5 mm or less (polyps we have termed "millimetric") studied in the Endoscopy Department of "La Paz" Hospital, Madrid, during 1993. All polyps fulfilling these characteristics detected during this period are included. The 178 polyps represent 43.4% of all polyps (N = 410) found on colonoscopy in this department in this period. The variables considered in the study protocol include age, sex, localization, morphology and histological examination, with particular attention to high risk histological lesions such as signs of possible malignancy.; we also performed a comparative study between the results obtained from the 178 millimetric polyps (Group I) and the 232 polyps greater than 5 mm (Group II) obtained during the same period. The endoscopic technique for the resection of the polyps was evaluated together with its possible complications. Although there were no significant differences found in respect to age, sex and location, there were morphological differences with a greater number of pediculated or semi-pediculated polyps in Group I whilst there were more sessile polyps in Group II. Adenomatous polyps were the most frequent (84%) in both groups. There was a greater incidence of signs of possible early malignant changes in Group II polyps (10) than in Group I (3.3%). The conclusions which may be drawn from our study are that it is clinically advisable to excise all polyps of 5 mm or less as the frequency of high risk histological changes is not negligible (3.3%), and excision is not problematic as the technique is easy and there have been no complications in our series.