Dysplasia-carcinoma sequence in diminutive polyps of the large bowel

The personal endoscopic experience regarding diminutive polyps (5 mm or less in diameter) of the colon and rectum is reported in order to evaluate the increased cancer risk related to these lesions. A total of 462 colo-rectal diminutive polyps, endoscopically removed by diathermy, have been considered in this study. The histopathologic examination of these lesions evidenced a high incidence of adenomatous polyps (69.9%), with dominance of the tubular histologic type. While mild dysplastic alterations were prevalent, moderate and severe dysplasia were observed to a lesser extent (18.9 and 1.9%) and only one case with focal carcinomatous area (1/323 = 0.3%) was recognized. In conclusion, for these lesions, even if minute in size, a dysplasia-carcinoma sequence should be considered whenever the adenomatous histologic type is evidenced and their increased risk of developing into cancer should be carefully evaluated for a correct diagnostic and therapeutic approach.