Endoscopic intermuscular dissection (EID) of a severely fibrotic benign rectal lesion in an area affected by radiation proctitis

The rectum is the ideal part of the large bowel in which to perform deep excision for dysplastic lesions [11] [22]. However, in cases of severe submucosal fibrosis and deep invasion of a carcinoma into the submucosa, performing endoscopic submucosal dissection can be very difficult. The intermuscular plane of dissection and myectomy of the inner muscular layer (endoscopic intermuscular dissection) previously have been described for treatment rectal neoplastic lesions, overcoming the compactness of the submucosa layer [33] [44] [55].

An 85-year-old man was referred to our department for a flat, 15-mm, dysplastic lesion (high-grade dysplasia [HGD]) close to the dentate line ([Fig. 1Fig. 1]). Morphologically, the polyp was a Paris Classification 0-IIa, NICE Classification: 2 and LST-Classification: NG-Type/Flat elevated. The patient had completed radiotherapy for prostate cancer 14 months before our evaluation and was treated with mesalamine enemas. The surrounding rectal mucosa was scarred and compact with white stripes and telangiectasias as a secondary effect of radiation. We decided to perform a deeper excision into the intermuscular plane to avoid the severely fibrotic submucosal plane ([Fig. 2Fig. 2], [Fig. 3Fig. 3], [Fig. 4Fig. 4] and [Video 1Video 1]). A single dose of broad-spectrum antibiotics was given interprocedurally to the patient. The defect remained open after the excision without any adverse events, such as bleeding, fever or pain, and the patient was discharged the next day ([Fig. 5Fig. 5]). The pathology report revealed tubular adenoma with HGD radically resected. Follow-up endoscopy in 6 months later revealed almost complete healing of the defect ([Fig. 6Fig. 6]).

Fig. 1 Fig. 1 A 15-mm flat polyp in the area affected by radiation proctitis.

Fig. 2 Fig. 2 Inability to lift the compact and fibrotic submucosal space by fluid injection.

Fig. 3 Fig. 3 Fluid injection into the intermuscular space.

Fig. 4 Fig. 4 Dissection between the inner (circular) and outer (longitudinal) muscle layers.

Fig. 5 Fig. 5 Open defect after removal of the dysplastic rectal lesion.

Fig. 6 Fig. 6 Healing of the dissection on follow-up endoscopy (6 months).

Endoscopic intermuscular dissection (EID) of a dysplastic severely fibrotic benign rectal lesion.Video 1Video 1

The dissection was performed between the inner circular and outer longitudinal muscles, instead of between the submucosal and muscle layers. The myectomy was achieved by using a Hook Knife (Olympus, Tokyo, Japan). Resecting benign severely fibrotic lesions in the rectum may constitute one of the advantages of EID, except in the case of resection of deeply infiltrative rectal carcinomas [55].

Video steps

HGD in the area affected by radiation proctitis

Starting mucosal incision without adequate lifting due to fibrosis

Compact and fibrotic submucosal space

Changing knife for myotomy

Entering intermuscular space

Injection to expand the tiny intermuscular space

Cautious intermuscular dissection

After completing circumferential incision, continuing with dissection

• References

• 1 Ohara Y, Toyonaga T, Tanaka S. et al. Risk of stricture after endoscopic submucosal dissection for large rectal neoplasms. Endoscopy 2016; 48: 62-70
• 2 Watanabe D, Toyonaga T, Ooi M. et al. Clinical outcomes of deep invasive submucosal colorectal cancer after ESD. Surg Endosc 2018; 32: 2123-2130
• 3 Rahni DO, Toyonaga T, Ohara Y. et al. First reported case of per anal endoscopic myectomy (PAEM): A novel endoscopic technique for resection of lesions with severe fibrosis in the rectum. Endosc Int Open 2017; 5: E146-E150
• 4 Toyonaga T, Ohara Y, Baba S. et al. Peranal endoscopic myectomy (PAEM) for rectal lesions with severe fibrosis and exhibiting the muscle-retracting sign. Endoscopy 2018; 50: 813-817
• 5 Moons LM, Bastiaansen B, Richir M. et al. Endoscopic intermuscular dissection (EID) for deep submucosal invasive cancer in the rectum: a new endoscopic approach. Endoscopy 2022;