A neuroendocrine tumor improper for ligation with suction was resected en bloc by underwater endoscopic submucosal dissection

For rectal neuroendocrine tumors (NETs) smaller than 10 mm, a meta-analysis indicated that endoscopic mucosal resection with suction, such as using a cap-fitted endoscope or ligating device, had a higher complete resection rate and significantly shorter procedure time compared to endoscopic submucosal dissection (ESD) [1]. In contrast, for NETs 10 to 14 mm in diameter that are improper for ligation with suction, ESD is feasible, although the treatment strategy has been controversial [2]. Herein, we report a case of a rectal NET that was successfully resected by underwater ESD (U-ESD) within a short time.

A man in his seventies underwent colonoscopy and was determined to have a slightly depressed submucosal tumor 10 mm in size in his lower rectum ([Fig. 1]). The tumor was diagnosed as a NET histologically by biopsy. Endoscopic ultrasonography suggested the lesion was confined to the submucosa ([Fig. 2]). Because suction was difficult due to the size of the lesion, the surgeon decided to resect it with U-ESD. The tumor was dissected in a layer just above the muscle layer and resected en bloc ([Fig. 3], [Fig. 4]; [Video 1]). The time for resection lasted 8 minutes. The wound was completely closed with clips. Histological findings showed a NET G1 according to the World Health Organization classification with a negative margin ([Fig. 5]). There was no evidence of vascular invasion. U-ESD enables submucosal dissection utilizing a floating effect in a magnified view [3]. In this case, the advantages of underwater conditions made it easy to proceed with the dissection at a depth just above the muscle layer, facilitating vertical margin negative excision. In conclusion, for lesions larger than approximately 10 mm, U-ESD can be a useful option for en bloc resection within a time that is comparable to endoscopic mucosal resection with suction.

Fig. 1 White light image before resection indicates a 10-mm yellowish, slightly depressed submucosal tumor located 2 cm from the anal verge in the lower rectum.

Fig. 2 Endoscopic ultrasonography revealed the lesion was in the submucosa.

Fig. 3 Submucosal dissection using a DualKnife J (KD-655Q; Olympus, Tokyo, Japan) just above the muscle layer was possible due to the floating effect in a magnified clear view in underwater conditions.

Fig. 4 The tumor was resected in a layer just above the muscle layer.

Video 1 Underwater endoscopic submucosal dissection for a neuroendocrine tumor in the lower rectum.

Fig. 5 Histological findings of the tumor. The tumor was diagnosed as a neuroendocrine tumor G1 according to the World Health Organization classification, with a negative margin (hematoxylin–eosin staining).

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Competing interests

The authors declare that they have no conflict of interest.

• References

• 1 Pan J, Zhang X, Shi Y. et al. Endoscopic mucosal resection with suction vs. endoscopic submucosal dissection for small rectal neuroendocrine tumors: A meta-analysis. Scand J Gastroenterol 2018; 53: 1139-1145
• 2 Hamada Y, Tanaka K, Mukai K. et al. Efficacy of endoscopic resection for rectal neuroendocrine tumors smaller than 15 mm. Dig Dis Sci 2023; 68: 3148-3157
• 3 Maida M, Sferrazza S, Murino A. et al. Effectiveness and safety of underwater techniques in gastrointestinal endoscopy: A comprehensive review of the literature. Surg Endosc 2021; 35: 37-51

Publication History

Article published online:
27 October 2023