**4.1 Diagnostic criteria for the 'DISCARD-ME' policy**

The diagnostic criteria in the 'DISCARD-ME' policy are basically according to the capillary pattern (CP) classification (Fig. 9), which has been reported to be useful for assessing the degree of dysplasia in early colorectal neoplasia (Katagiri et al., 2008). Lesions with invisible

Recent Advances in Diagnostic Endoscopy for Colorectal Neoplasm 221

Fig. 10. Pit pattern classification of surface pattern observed by narrow band imaging with magnifying endoscopy (NBI-ME). (A) Type I: NBI-ME image of submucosal tumor

(granular cell tumor). The surface pattern is normal, round and regular. (B) Type II: NBI-ME image of hyperplastic polyp. The surface pattern is star-like, slightly dilated and regular. (C) Type III: NBI-ME image of low-grade adenoma. The surface pattern is tubular, long and narrow, not branched and regular. (D) Type IV: NBI-ME image of villous high-grade adenoma. The surface pattern is branched, dendritic, villous or gyrus-like. (E) Type V: NBI-ME image of invasive carcinoma. The surface pattern is irregularly arranged and shaped

or faintly visible micro-capillary (MC) vessels are categorized as non-neoplastic (CP Type I), and lesions with clearly visible MC vessels are categorized as neoplastic. Neoplastic lesions are subdivided into low-grade dysplasia (CP Type II) and high-grade dysplasia or carcinoma (CP Type III). In CP type II, the MC vessels is arranged in a round or oval, honeycomb-like pattern. In CP type III, the MC vessels is not arranged regularly in a honeycomb-like pattern and exhibits at least one of the following features: irregular size, complex branching, disruption, or irregular winding.

Fig. 9. Capillary pattern (CP) classification using narrow band imaging with magnifying endoscopy (NBI-ME). (A) Type I: NBI-ME image of hyperplastic polyp. The microcapillary (MC) vessels are invisible or faintly visible. (B) Type II: NBI-ME image of low-grade adenoma. The MC vessels are arranged in a round or oval, honeycomb-like pattern. (C) Type III: NBI-ME image of invasive carcinoma. The MC vessels are not arranged regularly in a honeycomb-like pattern and exhibit at least one of the following features: irregular size, complex branching, disruption, or irregular winding

or faintly visible micro-capillary (MC) vessels are categorized as non-neoplastic (CP Type I), and lesions with clearly visible MC vessels are categorized as neoplastic. Neoplastic lesions are subdivided into low-grade dysplasia (CP Type II) and high-grade dysplasia or carcinoma (CP Type III). In CP type II, the MC vessels is arranged in a round or oval, honeycomb-like pattern. In CP type III, the MC vessels is not arranged regularly in a honeycomb-like pattern and exhibits at least one of the following features: irregular size,

Fig. 9. Capillary pattern (CP) classification using narrow band imaging with magnifying endoscopy (NBI-ME). (A) Type I: NBI-ME image of hyperplastic polyp. The microcapillary (MC) vessels are invisible or faintly visible. (B) Type II: NBI-ME image of low-grade adenoma. The MC vessels are arranged in a round or oval, honeycomb-like pattern. (C) Type III: NBI-ME image of invasive carcinoma. The MC vessels are not arranged regularly in a honeycomb-like pattern and exhibit at least one of the following features:

irregular size, complex branching, disruption, or irregular winding

complex branching, disruption, or irregular winding.

Fig. 10. Pit pattern classification of surface pattern observed by narrow band imaging with magnifying endoscopy (NBI-ME). (A) Type I: NBI-ME image of submucosal tumor (granular cell tumor). The surface pattern is normal, round and regular. (B) Type II: NBI-ME image of hyperplastic polyp. The surface pattern is star-like, slightly dilated and regular. (C) Type III: NBI-ME image of low-grade adenoma. The surface pattern is tubular, long and narrow, not branched and regular. (D) Type IV: NBI-ME image of villous high-grade adenoma. The surface pattern is branched, dendritic, villous or gyrus-like. (E) Type V: NBI-ME image of invasive carcinoma. The surface pattern is irregularly arranged and shaped

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In this pilot study, 105 lesions were detected. The histopathological diagnoses of two lesions were not obtained, histological diagnosis being available for the other 103 lesions (24 nonneoplastic lesions, 77 low grade adenomas, 1 high-grade adenoma, and 1 non-invasive

In 13 lesions (13%) which were endoscopically diagnosed as suspicious for high-grade adenoma or carcinoma, a decision was made to 'resect and send'. Of these 13 lesions, one was histopathologically diagnosed as high-grade adenoma and one as intramucosal carcinoma. Among the lesions for which the endoscopically made decisions were to 'resect and discard' or 'leave *in situ*', there were no high-grade adenomas or carcinomas. Therefore, it was concluded that decisions for management without formal histopathology could safely be made in 88% of small polyps (Fig. 12). The sensitivity of 'resect and send' for high-grade

Fig. 12. Flow diagram of the pilot study. In this pilot study, 'resect and send' could safely

Minimally invasive submucosal cancer is morphologically similar to intramucosal carcinoma, from which it is sometimes difficult to distinguish. Submucosal cancer should be assessed by histopathological examination for lymphovascular involvement and the vertical margin of the resected specimen to determine the need for additional surgery to prevent lymph node metastasis. With the 'DISCARD' policy without NBI-ME, there is a risk of small submucosal carcinomas being discarded, whereas the 'DISCARD-ME' policy could prevent inappropriate discarding. Furthermore, the 'DISCARD-ME' policy could be adopted in countries supporting the US guidelines, because these countries do not discard high-risk

The combination of AFI and TH results in more accurate detection of colorectal neoplasms. These new modalities lead to high yield colonoscopy, and the increase in detected lesions, resulting in more time, labor and cost being expended on the histopathological diagnosis of small indolent low-grade adenomas. The 'DISCARD-ME' policy using NBI-ME may

have been selected for the 13 lesions that included the 2 high-risk lesions, and histopathological examination was omitted for the remaining 88% of lesions

adenoma and carcinoma was 100%, and its specificity was 90%.

carcinoma).

lesions.

**5. Conclusion** 

When the microvascular architecture cannot be assessed, the pit pattern classification of surface pattern is applied, because Hirata et al. have reported that determination of the pit patterns of colorectal neoplasia by NBI-ME is almost the same as that achieved by standard magnification with chromo-endoscopy (Hirata, et al., 2007, Fig. 10). According to the pit pattern classification, lesions with Type I and II pit patterns are categorized as nonneoplastic, and lesions with Type III, IV and V pit patterns as neoplastic (Kudo, et al., 1994). Neoplastic lesions with a Type III pit pattern are categorized as low-grade adenomas and lesions with Type IV and V pit pattern as high-grade adenomas, villous adenomas or carcinomas. In cases where different histologic categories have been assigned by the CP and pit pattern classifications, the more severe category is adopted.
