Hurowitz and Stubbs raise the question of suitable management for patients known to have small polyps ( 5 mm) on flexible sigmoidoscopy. Controversy continues to surround management of patients who have a small tubular adenoma on screening flexible sigmoidoscopy and whether they should undergo colonoscopy of the proximal colon. It is not only the size of a polyp but also the underlying histologic characteristics that should determine appropriate management. Most authorities consider polyps to have advanced features if the polyps are greater than 1.0 cm or if they have a villous or tubulovillous structure. The seemingly disparate results in the studies reported by Read and colleagues (1) and Wallace and coworkers (2) can be reconciled if one examines the composition of the patient groups. Read and colleagues included patients with advanced distal polyps (that is, tubulovillous or villous adenomas); such lesions have been shown in other series to be clearly associated with a higher prevalence of advanced proximal polyps. By contrast, Wallace and colleagues did not include any patients with villous or tubulovillous lesions but restricted their study to patients with tubular lesions 1 to 5 mm or 6 to 10 mm in diameter. The results obtained by Wallace and associates are in accord with those of an earlier study by Zarchy and Ershoff (3), who found that only 1 of 124 patients (0.8%) who had polyps without advanced histologic features (<1 cm and absence of a villous or tubulovillous pattern) actually had a proximal lesion.

To summarize, the accumulated evidence indicates that patients with small tubular adenomas have a less than 1% chance of harboring a proximal lesion. On the other hand, even diminutive polyps ( 5 mm in diameter), if they have advanced histologic features consisting of a villous or tubulovillous pattern, are associated with a higher risk for proximal lesions.