Endoscopic Criteria Used to Distinguish Benign From Malignant Polyps

Abstract

Aims: The goal of our study is to determine the visual characteristics used by endoscopists to decide whether a polyp is benign or malignant. Design: A video disc containing 20 cases of 8 benign and 12 malignant polyps was sent to endoscopists of varying experience. The respondent was asked to view the video of each polyp and then fill out a questionnaire which listed various characteristics (size, color, margins, surface irregularity, depression, ulceration, bleeding, waxy, and nodularity) and make a visual estimation as to whether the polyp was benign, malignant or indeterminate. Results: Our sample consisted of responses from 61 physicians (1220 observations). Overall, 68% of the responses were correct, 65% of the benign polyps were identified correctly, as were 70% of the malignant polyps. There were substantial differences in the rate of correct response by question, ranging from 27% to 98%. Gastroenterology fellows answered correctly 67% of the time, whereas, gastroenterology attendings responded correctly 69% of the time (the difference was not statistically significant). The criteria of size, irregularity, margins, and color were used more often when describing a malignant polyp. Lack of nodularity and size were used more often when describing a benign polyp. These differences were statistically significant. Surprisingly, irregularity showed a negative association with correctly identifying the polyp as benign (p-value <0.01). In a logistic regression of the overall data for both benign and malignant polyps, the use of ulceration was most positively associated with the likelihood of a correct answer. Color and margins were also predictive of a correct answer. Although “waxiness” is a term often cited in the literature as a determining visual characteristic, it was rarely used in these responses. Taken together, these results suggest that ulceration in a polyp, combined with an evaluation of its margins and its size increase the likelihood of correctly differentiating between a benign and a malignant polyp. Conclusion: Size, margins, bleeding and ulceration were the visual characteristics most often used by physicians to differentiate benign from malignant polyps. Malignant polyps are most often correctly diagnosed by their larger size, irregular margins, bleeding and surface ulcerations. Conversely, smaller size and lack of irregular margins are often used as determinants of benign polyps.