Utilization of methylene blue–based submucosal injection to identify residual neuroendocrine tumor in the colon after endoscopic biopsy sampling

Post written by Weina Jing, MD, and Kai Deng, MD, from the Department of Gastroenterology & Hepatology, West China Hospital, Sichuan University, Chengdu, Sichuan, China.


This study provides a new way to find small residual neuroendocrine tumors. Submucosal staining assisted in the identification of minor lesions in the lamina propria of the mucosa.

Neuroendocrine tumors of the GI tract are potentially malignant and should be resected, but some small neuroendocrine tumors are difficult to recognize after biopsy.


At present, the biopsy sampling scar is usually used to find the residual neuroendocrine tumor, but there is no very effective way to locate the residual neuroendocrine tumor whose scar has completely healed. Thus, how to effectively identify small neuroendocrine tumors needs to be solved.

Through this case, we found that, for some lesions that are very tiny and difficult to be identified by the naked eye, methylene blue can be injected into the submucosa to increase the color contrast between the lesion and the surrounding mucosa to identify the lesion. In this regard, some difficult-to-identify lesions could be located.

However, because this is only a case report, future efforts should be focused on expanding population and standardizing this method.

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The procedure flowchart of injecting methylene blue to identify a tiny lesion of the residual neuroendocrine tumor (NET). A, A tiny NET was revealed by the colonoscopy with biopsy sampling. B, After several months, the biopsy sampling wound healed completely, and the mucosa was smooth. C, Injecting a higher concentration of methylene blue into the submucosa exposed the residual lesion. D, The residual lesion could be identified by increasing the color contrast between the lesion and background mucosa. EP, Epithelium; MM, muscularis mucosa; SM, submucosa; MP, muscularis propria.

Read the full article online.

The information presented in Endoscopedia reflects the opinions of the authors and does not represent the position of the American Society for Gastrointestinal Endoscopy (ASGE). ASGE expressly disclaims any warranties or guarantees, expressed or implied, and is not liable for damages of any kind in connection with the material, information, or procedures set forth.

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