Endoscopic intermuscular dissection of early anal cancer

Anal cancer accounts for 0.5% of all new cancer cases, with an observed annual increase in incidence of up to 2.7% over the past decade [1]. This increase has closely mirrored the rise in human papillomavirus infections, the most important risk factor for anal cancer. According to international guidelines [2] [3] [4], marginal/perianal lesions smaller than 2 cm without lymphatic involvement or metastatic spread can be curatively treated with complete local excision, thereby sparing patients the adverse effects of surgery or chemoradiotherapy. Here, we describe a case of early anal cancer which was successfully treated by endoscopic intermuscular dissection (EID).

A 44-year-old woman presented with rectal blood loss. Colonoscopy revealed a 30-mm laterally spreading polyp with a large nodule and involvement of the dentate line. Endoscopic assessment showed an unusual pit pattern on the top of the large nodule ([Fig. 1]). Virtual chromoendoscopy showed nonstructured, amorphous pits and nearly avascular and loose microcapillary vessels ([Fig. 2]). As deep submucosal invasion was suspected, EID was performed (see step-by-step explanation in [Video 1]). We used a conventional video endoscope (GIF-TH190; Olympus, Germany) with a small-caliber-tip transparent hood (DH-28GR; Fujifilm, Japan) fitted to the tip of the endoscope. A FlushKnife BT (DK2618JB-15; Fujifilm, Japan) was used for incision and dissection. For electrical cutting and coagulation, a VIO 300D electrosurgical generator (Erbe Elektromedizin, Germany) was used. EID was carried out using the tunneling method [5]: an intermuscular tunnel was created from the anal canal to the proximal side in the distal rectum, followed by mobilization of the lateral edges. Complete en bloc resection was achieved ([Fig. 3], [Fig. 4]; total procedure time 120 min). Histological analysis showed a T1Sm2 squamous cell carcinoma with free resection margins (>2 mm) and no signs of lymphovascular invasion or high-grade tumor budding ([Fig. 5]).

Fig. 1 White-light imaging of the top of a large anal nodule showing an unusual pit pattern in a 44-year-old woman presenting with rectal blood loss.

Fig. 2 Narrow-band imaging of the top of the large nodule showing nonstructured, amorphous pits and nearly avascular and loose microcapillary vessels.

Fig. 3 Endoscopic view of the resection site after endoscopic intermuscular dissection (EID).

Fig. 4 Macroscopic view of the resected specimen.

Fig. 5 Histological analysis of the resected specimen (hematoxylin-eosin stain) showing a T1Sm2 squamous cell carcinoma with free resection margins (>2 mm).

Endoscopic intermuscular dissection of early anal cancer: step-by-step demonstration of the procedure.Video 1

In conclusion, EID is a feasible and potentially curative treatment option for small, localized early-stage anal cancers.

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Publication History

Article published online:
05 June 2024

• References

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