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Usefulness of the Japan narrow-band imaging expert team classification system for the diagnosis of sessile serrated lesion with dysplasia/carcinoma

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Abstract

Background

Sessile serrated lesion (SSL) is a colorectal polyp that has malignant potential. However, the dysplastic components within an SSL can be difficult to diagnose with conventional endoscopy, because most SSLs with dysplasia/carcinoma have subtle mucosal features. Many studies have indicated that narrow-band imaging (NBI) observations of colorectal polyps are very useful, accurate predictors of histology. We aimed to verify the usefulness of the Japan NBI Expert Team (JNET) classification system for the diagnosis of SSLs with dysplasia/carcinoma.

Methods

We examined 709 endoscopically or surgically resected lesions that were pathologically diagnosed as SSL, including 647 with no dysplasia, 37 with low-grade dysplasia, 15 with high-grade dysplasia, and 10 with submucosal invasive carcinoma. We retrospectively evaluated their clinicopathologic characteristics and conventional endoscopic and magnifying NBI endoscopic findings using the JNET system.

Results

Cases in all groups were more frequently located in the proximal colon. Submucosal invasive carcinomas were significantly larger than no dysplasia and low-grade dysplasia lesions. Almost all studied lesions (96.3%) were covered with a mucus cap. Five hundred and eighty (81.8%) lesions exhibited dark spots inside the crypts, which are NBI findings’ characteristic of SSL. As for the JNET classification of magnifying NBI endoscopic findings, all 709 lesions showed Type 1. Six hundred and eighteen (95.5%) SSLs with no dysplasia lesions exhibited Type 1 only, whereas 52 (83.9%) SSLs with dysplasia/carcinoma had a combination of Type 1 and Type 2A, 2B, or 3, corresponding to SSL and dysplasia/carcinoma, respectively. The JNET classification had high sensitivity (83.9%), specificity (95.5%), and overall diagnostic accuracy (94.5%) for diagnosing SSLs with dysplasia/carcinoma.

Conclusions

Use of magnifying NBI endoscopy with the JNET classification might be useful for diagnosing SSLs with dysplasia/carcinoma. This increased awareness may also improve the recognition of SSLs with dysplasia/carcinoma.

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Authors and Affiliations

  1. Department of Gastroenterology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan

    Takashi Murakami, Naoto Sakamoto, Hirofumi Fukushima, Tomoyoshi Shibuya & Akihito Nagahara

  2. Department of Human Pathology, Juntendo University School of Medicine, Tokyo, Japan

    Takashi Yao

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  1. Takashi Murakami
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  2. Naoto Sakamoto
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  3. Hirofumi Fukushima
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  4. Tomoyoshi Shibuya
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  5. Takashi Yao
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  6. Akihito Nagahara
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Contributions

T. Murakami mainly contributed to this work, analyzed data, and wrote the manuscript; N. Sakamoto and H. Fukushima evaluated the endoscopic findings; T. Murakami and T. Yao pathologically reviewed the cases; T. Shibuya and A. Nagahara contributed equally to the writing of the manuscript.

Corresponding author

Correspondence to Takashi Murakami.

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Disclosures

Takashi Murakami, Naoto Sakamoto, Hirofumi Fukushima, Tomoyoshi Shibuya, Takashi Yao, and Akihito Nagahara have no conflicts of interest or financial ties to disclose.

Ethical approval

This study was approved by the Institutional Review Board and the ethical committee of our hospital (reference number 2017166). The study was performed in accordance with the principles of the Declaration of Helsinki.

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Written informed consent was waived because the study was retrospective in design.

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Murakami, T., Sakamoto, N., Fukushima, H. et al. Usefulness of the Japan narrow-band imaging expert team classification system for the diagnosis of sessile serrated lesion with dysplasia/carcinoma. Surg Endosc 35, 4528–4538 (2021). https://doi.org/10.1007/s00464-020-07967-w

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