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En Bloc Endoscopic Mucosal Resection of a Large Right Colonic Serrated Lesion

      Abstract

      Sessile serrated lesions (sessile serrated adenomas or polyps), particularly in the proximal colon, are increasingly recognized as premalignant lesions, which require removal; however, to remove these flat and indistinct lesions in the thin-walled right colon can be technically demanding. In this article, en bloc endoscopic mucosal resection technique is demonstrated for a 12-mm sessile serrated lesion in the proximal colon. This article is part of an expert video encyclopedia.

      Keywords

      Video Related to this Article

      Materials

      • Endoscope: CF-H260 DL; Olympus KeyMed, Southend-on-Sea, UK.
      • Injection solution: 19 ml Gelofusine, 1 ml 1:10 000 epinephrine, a few drops of methylene blue.
      • 10-mm Snare, Snaremaster, Olympus.

      Background and Endoscopic Procedures

      It is now widely recognized that there is an alternative ‘serrated’ pathway to colorectal cancer, distinct from the standard adenoma carcinoma sequence, which accounts for 20–30% of colorectal cancer. The lesions that this subgroup of cancers derives from have distinct molecular–genetic characteristics with BRAF mutations and high levels of methylation.
      • East J.E.
      • Saunders B.P.
      • Jass J.R.
      Sporadic and Syndromic Hyperplastic Polyps and Serrated Adenomas of the Colon: Classification, Molecular Genetics, Natural History, and Clinical Management.
      • Leggett B.
      • Whitehall V.
      Role of the Serrated Pathway in Colorectal Cancer Pathogenesis.
      Adenomas do not show these changes; however, a subset of hyperplastic polyps do, so-called sessile serrated polyps, also called sessile serrated adenomas. These occur more commonly in the proximal colon, are usually flat (Paris 0 – IIa or IIb), and are difficult to detect. Chromoendoscopy or narrow band imaging may aid detection.
      • East J.E.
      • Saunders B.P.
      • Jass J.R.
      Sporadic and Syndromic Hyperplastic Polyps and Serrated Adenomas of the Colon: Classification, Molecular Genetics, Natural History, and Clinical Management.
      • Boparai K.S.
      • van den Broek F.J.
      • van Eeden S.
      • Fockens P.
      • Dekker E.
      Increased Polyp Detection Using Narrow Band Imaging Compared with High Resolution Endoscopy in Patients with Hyperplastic Polyposis Syndrome.
      Characteristically they have a mucus cap that can be difficult to wash off, which can alert the endoscopists to their presence.
      In this video, a large sessile serrated polyp is seen in the proximal colon, highlighted by chromoendoscopy. Injection into the lesion is performed after careful inspection for invasive features. Although there are concerns about carrying dysplastic cells into the submucosa by injecting through the lesion, we feel that achieving a high, discreet, vertical lift to enable safe en bloc resection is more important than this theoretical risk. Gelofusine is used as the lift solution as there is evidence to suggest that this lasts longer and leads to fewer resection pieces than saline.
      • Moss A.
      • Bourke M.J.
      • Metz A.J.
      Arandomized, Double-Blind Trial of Succinylated Gelatin Submucosal Injection for Endoscopic Resection of Large Sessile Polyps of the Colon.
      A small amount of epinephrine in the solution is used to avoid oozing and ensure a bloodless field. Methylene blue in the solution is used to stain the submucosa. For serrated polyps, this is especially useful if working without dye spray, as once lifting is started, without blue contrast behind the lesion, the edges of the polyp can become difficult to see.
      • East J.E.
      • Saunders B.P.
      • Jass J.R.
      Sporadic and Syndromic Hyperplastic Polyps and Serrated Adenomas of the Colon: Classification, Molecular Genetics, Natural History, and Clinical Management.
      Indigo carmine would be an alternative. A small stiff snare is employed, which can be pressed downward firmly on the lifted lesion to protrude tissue through the snare. In combination with suction to deflate the colon, this usually allows even the flattest lesion to be grasped. Rapid tissue transection with firm snare closure and the use of Endocut minimizes diathermy injury to the colonic wall. Delayed perforation is a more serious complication than delayed bleeding, and so rapid tissue transection is preferable to minimize the risk of transmural injury or serositis. Resection needs to be comprehensive as there are reports of rapid development of carcinoma where serrated polyps have been resected.
      • Goldstein N.S.
      • Bhanot P.
      • Odish E.
      • Hunter S.
      Hyperplastic-Like Colon Polyps that Preceded Microsatellite-Unstable Adenocarcinomas.
      Fragments at lesion edges can be resected with further snaring or ablated with argon plasma coagulation (APC). Data from a large series of endoscopic mucosal resections of adenomas suggests APC use is associated with higher recurrence rates, so snaring is preferred.
      • Moss A.
      • Bourke M.J.
      • Williams S.J.
      • et al.
      Endoscopic Mucosal Resection Outcomes and Prediction of Submucosal Cancer from Advanced Colonic Mucosal Neoplasia.
      Ideally, lesions up to 20 mm would be resected en bloc as shown here, but great care needs to be taken for larger lesions to avoid grasping underlying muscle, and optimal technique is required.
      Serrated lesions are likely to become more widely recognized and therefore there will be an increasing need for skilled, safe resection, especially in the thin-walled right colon. Endoscopists should be mindful of the risks of resection when approaching these lesions. Larger lesions may need to be referred to specialist therapeutic endoscopists.

      Key Learning Points/Tips and Tricks

      • Define the edge of the lesion with dye spray beforehand or with dye in the lift solution.
      • Inject centrally and angle away during lifting to produce maximum vertical lift.
      • Press down firmly and apply suction with a stiff snare to maximize tissue grip.
      • Review the lesion defect carefully for residual polyp.

      Scripted Voiceover

      Tabled 1
      Time (min:sec)Voiceover text
      00.03 – StartA 12 mm flat serrated lesion is seen highlighted by chromoendoscopy. Careful inspection shows no areas of suspected adenomatous change or depressed elements.
      00.20 – InjectionInjection to lift the lesion is performed. Note that the injection is placed centrally in the lesion. As injection continues the needle is lifted away from the lesion to achieve a high lift directly under the lesion with minimal lateral dispersal.
      00:38 – Post-liftThe lesion is well lifted on a hemispherical dome of gelofusin. This “half golf ball” shape helps the snare engage the sides of very flat lesions.
      00:53 – SnaringA small stiff snare is placed over the lesion and downward pressure and suction is applied to protrude the lesion though the snare and help with grip. The bulge through the snare means that all polyp tissue is captured.
      01:13 – MovementThe polyp is moved back and forth to ensure that it moves freely on the wall and that underlying muscle has not been snared.
      01.21 – Open-closeThe snare is slightly opened and closed to allow muscle that might have been snared to drop back.
      01.28 – CuttingThe polyp is then resected, with rapid snare closure and “Endocut”. This ensures minimal diathermy injury to the thin wall of the right colon.
      01:38 – Inspection defectThe defect is now carefully inspected looking for over deep resection the so called “target sign”, bleeding from vessels, or residual polyp tissue at the lesion edge. In this case the lesion has been resected en bloc and there is no residual tissue. Should fragments be seen they can be further snare resected or ablated with argon plasma coagulation.

      References

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        • Saunders B.P.
        • Jass J.R.
        Sporadic and Syndromic Hyperplastic Polyps and Serrated Adenomas of the Colon: Classification, Molecular Genetics, Natural History, and Clinical Management.
        Gastroenterol. Clin. North Am. 2008; 37: 25-46
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        • Whitehall V.
        Role of the Serrated Pathway in Colorectal Cancer Pathogenesis.
        Gastroenterology. 2010; 138: 2088-2100
        • Boparai K.S.
        • van den Broek F.J.
        • van Eeden S.
        • Fockens P.
        • Dekker E.
        Increased Polyp Detection Using Narrow Band Imaging Compared with High Resolution Endoscopy in Patients with Hyperplastic Polyposis Syndrome.
        Endoscopy. 2011; 43: 676-682
        • Moss A.
        • Bourke M.J.
        • Metz A.J.
        Arandomized, Double-Blind Trial of Succinylated Gelatin Submucosal Injection for Endoscopic Resection of Large Sessile Polyps of the Colon.
        Am. J. Gastroenterol. 2010; 105: 2375-2382
        • Goldstein N.S.
        • Bhanot P.
        • Odish E.
        • Hunter S.
        Hyperplastic-Like Colon Polyps that Preceded Microsatellite-Unstable Adenocarcinomas.
        Am. J. Clin. Pathol. 2003; 119: 778-796
        • Moss A.
        • Bourke M.J.
        • Williams S.J.
        • et al.
        Endoscopic Mucosal Resection Outcomes and Prediction of Submucosal Cancer from Advanced Colonic Mucosal Neoplasia.
        Gastroenterology. 2011; 740: 1909-1918