Superficial anal canal squamous cell carcinoma diagnosed using NBI and treated by ESD

What is it about?

An 82-year-old woman with a history of surgery for superficial rectal cancer underwent surveillance colonoscopy. In the forward view, nothing was detectable in the anorectal area, but a lesion was detected as a slightly pale-colored area with an indistinct border in the retroflex view using white light imaging (Fig. 1a). Narrow-band imaging (NBI) without magnification demonstrated this lesion more clearly as a slightly whitish and depressed area 30 mm in diameter, showing the Herrmann line extending partially outside (Fig. 1b). Magnifying NBI in the depressed area revealed various abnormally looped vessels showing dilation, meandering, and caliber irregularity, resembling the intraepithelial papillary capillary loops seen in squamous esophageal carcinoma (Fig. 1c,d).1 The vessels were sparsely distributed, and the area between them was whitish, and not brownish. Computed tomography showed no lymph node or distal metastasis. The lesion was diagnosed as a superficial anal canal carcinoma, and histological examination of a biopsy specimen demon- strated squamous cell carcinoma (SCC). We carried out local resection using endoscopic submucosal dissection (ESD) because the patient declined chemoradiotherapy. Pathological examination demonstrated SCC invading the submucosal layer (Fig. 2a–c). In the present case, anal SCC was detected as a whitish area with extension of the Herrmann line using NBI, whereas SCC in the esophagus had been described as a brownish area in previous reports.2 Using NBI, Morisaki et al. found that SCC in the anal canal appeared whitish because of the sparser distribution of vessels in the anal region in comparison with the esophagus or pharynx.3 It is difficult to demonstrate the macroscopic type and color of a lesion using white light imaging; thus, a search using NBI in retroflex view to determine whether the Herrmann line shows outward extension might facilitate detection of anal canal SCC at an earlier stage.

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