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Live CaseESDMuscle Retraction SignOesophageal cancerDeep marginEIDSquamous cell cancer
Live Case - Muscle Retraction Sign in Oesophageal ESD
This live case captures real-time identification and management of the Muscle Retraction Sign (MRS) during ESD of a biopsy-proven mid-oesophageal squamous cell cancer. Learn how directionality and asymmetric submucosal injection reveal deep SM invasion, how to navigate the EID intramuscular plane deliberately, and how to re-enter the submucosa to achieve a negative deep margin.
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Course Preview
The key diagnostic moment: instructor explains that directionality is everything, demonstrates working from the surface in neutral position, then shows asymmetric submucosal injection revealing no plane in the zone of maximal abnormality — MRS identified in real time.
"Directionality is everything in the detection of the muscle retraction sign. For deep margin optical diagnosis, you need to work from the surface."
Overview
The Muscle Retraction Sign (MRS), first described by Toyonaga for colorectal ESD, is increasingly recognised as a pan-GI tract phenomenon. In this live case, the sign is captured in real time during ESD of a biopsy-proven mid-oesophageal squamous cell cancer — with expert commentary narrating every decision from initial recognition through to final dissection.
"If you want to go back into the submucosa plane, all I have to do is cut between two known submucosal planes."
Key Learning Points
- Directionality is everything. MRS detection requires working from the surface in a neutral endoscope position and matching orientation between the external view and the tunnel interior.
- Asymmetric submucosal lift is the diagnostic signal. On injection, the normal margin lifts with blue staining while the zone of maximal abnormality shows no submucosal plane — the invasive front is optically identified before a single cut is made.
- MRS indicates deep SM invasion, not T2. Deep SM invasion may still be manageable within an ESD resection, while T2 disease generally precludes endoscopic cure.
- The EID principle: "If you want to go back into the submucosa, all you have to do is cut between two known submucosal planes." The muscular patch on the specimen confirms the resection line passed through and beyond the zone of invasion.
- MRS applies throughout the GI tract. The oesophageal appearance is almost identical to the colorectal image first described — validating its use as a pan-GI deep margin indicator.
"I do believe we're looking at the invasive front here. That muscle retraction sign named by Toyonaga."
Clinical Relevance
For advanced endoscopists performing oesophageal ESD, the ability to optically diagnose deep margin involvement during dissection — and modify the dissection plane accordingly — determines whether a resection achieves a negative or positive deep margin. This case is linked to an in-preparation publication describing MRS specifically in the oesophagus.
Who Should Watch
Advanced endoscopists with experience in ESD who want to deepen their understanding of deep margin optical diagnosis and deliberate intramuscular plane management in oesophageal lesions.
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