No abstract

Magnification with chromoendoscopy is the most reliable method to determine whether colorectal lesions are neoplastic or notWe have read the article of Sonwalkar et al. with great interest [1]. They conducted a noncomparative retrospective study to assess the differential diagnostic accura− cy of nonmagnifying chromoendoscopy for pit pattern analysis, and concluded that nonmagnifying chromoendoscopy can be used to distinguish neoplastic from nonneoplastic colonic polyps. We routinely use magnifying colonosco− py for examination as it provides not only the conventional view but also a magnified one for observation after dye spraying for histology prediction on the basis of pit patterns [2]. As the authors mention in their discussion, we conduct− ed a retrospective study to assess the di− agnostic potential of pit patterns for his− tology prediction [2]. As the result was not as satisfactory as expected because of the biased retrospective design, we con− ducted a prospective study to make sure [3]. The overall diagnostic accuracy was as high as 99.1 %, and we therefore report− ed that magnifying colonoscopy could be used by well−trained colonoscopists as a nonbiopsy technique for differentiating neoplastic from nonneoplastic polyps. Moreover, as lesions are often initially di− agnosed by the conventional view, and are then evaluated by chromoendoscopy with magnification followed by chromo− endoscopy during magnifying colono− scopic examinations, we have conducted a second comparative prospective study to clarify whether spraying dye and using magnification at each step confers any improvement in comparison with the conventional view [4]. The overall diag− nostic accuracy of chromoendoscopy with magnification was 95.6 %, which was 10 % greater than the conventional view and 5 % greater than chromoendos− copy without magnification. For this rea− son, we conclude that chromoendoscopy with magnification is the most reliable method by which to determine whether a colorectal lesion is neoplastic or non− neoplastic. It is true that, if nonmagnifica− tion could provide the same result as magnification for pit pattern analysis, it would be much more effective and con− venient. Interestingly, our diagnostic ac− curacy with chromoendoscopy before magnification was similar to the results of Sonwalkar et al. using nonmagnifying colonoscopy; however, we found that ad− ditional magnification provided signifi− cantly better diagnostic accuracy. Thus, nonmagnification colonoscopy seems to be insufficient for pit pattern analysis and would result in wasting of resources or in an increase in complications for pa− tients due to unnecessary endoscopic re− section or to undertreatment. The marginal difference in diagnostic ac− curacy between our two prospective studies can be explained by the fact that the second one only included lesions 10 mm in size or smaller, as most lesions larger than 10 mm are neoplastic and most lesions encountered at colonoscopy are 10 mm or less. Furthermore, even if lesions 10 mm or larger are diagnosed as h...

Acetic acid as an effective mucolytic in magnification with chromoendoscopy for pit patterns analysisWe have read the article of Togashi et al. with great interest [1]. They have com− pared the accuracy of predicting polyp histology at magnification colonoscopy using acetic acid and indigo carmine, ei− ther alone or in combination. They have shown that use of acetic acid spray in− stantly improves the pit pattern image during magnification chromoendoscopy and has high accuracy in the histological prediction of colorectal polyps. They state that acetic acid is particularly effective because it rapidly removes the mucus that can make pit pattern analysis diffi− cult, and the aceto−white reaction accen− tuates the pit pattern. However, they have shown that acetic acid increases the accu− racy more for adenomas (76 % ± 94 %) than for hyperplastic polyps (92 % ± 100 %). Generally, hyperplastic polyps are found as diminutive sessile polyps especially in the rectum and sigmoid colon. Endoscop− ically, hyperplastic polyps rather than adenomas correspond to sessile, pale polyps with a smooth surface and a par− tial or complete surface covering of mu− cus. Therefore, if acetic acid is an effective mucolytic, as expected by the authors, it should improve the diagnostic accuracy for hyperplastic polyps rather than for adenomas. Furthermore, the authors have shown that acetic acid alone (95 %) achieves higher accuracy overall than indigo car− mine alone (83 %), although this differ− ence did not reach statistical significance, possibly due to the small sample size. We conducted a prospective study to clarify whether using dye spraying and magnifi− cation at each step contributes to further endoscopic distinction in comparison with the conventional endoscopic view [2]. The overall diagnostic accuracy achieved with chromoendoscopy using indigo carmine with magnification was 95.6 % ± significantly better (by 10 % and 5 % respectively) than the accuracy achieved with either the conventional view or with chromoendoscopy without magnification. Therefore, the result of Togashi et al. in relation to the diagnostic accuracy of indigo carmine with magnifi− cation seems to be lower than expected. References1 Togashi K, Hewett DG, Whitaker DA et al. The use of acetic acid in magnification chromo− colonoscopy for pit pattern analysis of small polyps. Endoscopy 2006; 38: 613 ± 616 2 Fu KI, Sano Y, Kato S et al. Chromoendoscopy using indigo carmine dye spraying with magnifying observation is the most reliable method for differential diagnosis between non−neoplastic and neoplastic colorectal le− sions: a prospective study. Endoscopy