Residual stalks of pedunculated adenomas. An underrecognized type of colonic polyp.

Variable lengths of stalk of colonic pedunculated adenomas may be left behind at polypectomy. At follow-up endoscopy, a residual stalk is a smooth-surfaced, sessile polyp, without a distinct head, and may be difficult to remove. It may be mistaken endoscopically for either a recurrent adenoma or a polyp missed at the original procedure. Histologically, it has a coat of normal mucosa and a core of submucosa in which recanalized blood vessels, scarring, and hemosiderin deposition (consequences of thermocautery) may be seen. We present four cases illustrating the clinicopathologic problem and the pathologic appearances. One caused clinical concern because of its size and location at the site of former polypectomy. One was histologically confusing and raised the question of a vascular malformation. The third, seen at segmental colectomy after endosocopic biopsy of an adenoma, illustrates the gross appearances. The fourth contained regenerative mucosa and recanalized submucosal blood vessels.