HUMAN TISSUE RESPONSES TO METAL STENTS IMPLANTED IN-VIVO FOR THE PALLIATION OF MALIGNANT STENOSES

Background: We sought to determine the histologic effects of metal ste nt placement on tumor tissue and on normal tissue proximal and distal to the tumor in patients with expandable metal stents implanted in viv o. Methods: Twelve patients with 10 to 16 mm uncovered Wallstents were studied, 5 with esophageal stents, 4 with biliary stents and 3 with a ntral-duodenal stents. Stent duration ranged from 18 days to 15 months . Eleven autopsy specimens and one surgical specimen were examined, Th e organs with the stent in place were removed, and histologic specimen s were obtained using a special saw-microtome that cuts through the ti ssue and the material of the stent. Results: In all organs examined, t he stent was incorporated into the material of the tumor to a varying degree. In the normal areas above and below the stenosis, the stent wa s incorporated into the wall of the organ and was covered by a collage nous reactive layer on the luminal aspect. The collagenous reaction wa s limited and did not cause exuberant growth or obstruction in any of the cases. Conclusions: The struts of uncovered Wallstents of 10 to 16 mm in diameter migrate into the submucus space above and below the tu mor, probably by pressure necrosis, and become incorporated into the w all of the organ.