Novel diagnostic methods for early-stage squamous cell carcinoma of the anal canal successfully resected by endoscopic submucosal dissection

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Although anal canal squamous cell carcinoma (ACSCC) is quite rare, it can be recognized clearly using iodine staining [1]. Early-stage esophageal squamous cell carcinoma (SCC) has recently been diagnosed using both narrow-band imaging (NBI) [2] and autofluorescence imaging (AFI) [3]. Here we report on the first case of early-stage ACSCC diagnosed by NBI and AFI and treated successfully by endoscopic submucosal dissection (ESD).

A 70-year-old woman was referred to our hospital for treatment of ACSCC. Conventional colonoscopy (PCF-Q240Z, Olympus Optical Co., Tokyo, Japan) revealed a slightly protruded lesion approximately 10 mm in size and located close to the dentate line ([Fig. 1]). The superficial microvessels of the lesion were examined by white light and NBI systems with magnification ([Fig. 2]), and appeared similar to esophageal intraepithelial papillary capillary loops (IPCLs) [4]. The AFI image was purple in color ([Fig. 3 d]), and the lesion was unstained following iodine staining. NBI, AFI, and iodine staining images were similar to those of esophageal SCC ([Fig. 3]) [3] [4].

An endoscopic diagnosis of carcinoma in situ was made because of the IPCL-like microvessels; ESD was performed ([Fig. 4]) [5] because the location of the lesion caused technical difficulties in achieving an en-bloc endoscopic mucosal resection. Histopathological analysis of the resected specimen revealed SCC, with microinvasion of 0.4 mm but no lymphovascular invasion ([Fig. 5]). Chemoradiation therapy, with a dose-reduction of 25 %, was carried out because of the microinvasion. A follow-up colonoscopy performed 23 months later revealed the ESD scar ([Fig. 6]), and the biopsy specimen was negative for malignancy.

Fig. 1 Conventional colonoscopy showed a slightly protruded lesion (white circle) measuring approximately 10 mm in the lower rectum close to the dentate line.

Fig. 2 a ,b Magnified conventional white light views of the mildly protruded lesion showed dilatation, weaving, and elongation of intraepithelial papillary capillary loops (IPCL)-like microvessels. c, d Magnified narrow-band imaging colonoscopic views clearly showed dilatation, weaving, and elongation of IPCL-like microvessels.

Fig. 3 Different views of the lesion. a Conventional white light. b Narrow-band imaging. c Chromoendoscopy (iodine-staining). d Autofluorescence imaging.

Fig. 4 Pictures of the endoscopic submucosal dissection procedure.

Fig. 5 a Resected specimen (10 × 40 mm). Orange lines indicate mucosal (m) cancer areas. The red line indicates the submucosal (sm) invasion area. b Hematoxylin and eosin staining. c Original magnification of black square shown in b (× 80). The submucosal invasion was 0.4 mm, estimated by the putative line extending from the muscularis mucosa of the colorectal mucosa.

Fig. 6 The follow-up pictures of colonoscopy after endoscopic submucosal dissection and chemoradiation therapy. a Conventional colonoscopic view. b Close-up conventional colonoscopic view. c Iodine-stained chromoendoscopic view. The resection area is shown as iodine-stained. d Magnified chromoendoscopic view. The resection was iodine-stained, and there were no abnormal IPCL-like microvessels.

Endoscopic diagnosis of ACSCC and an accurate prediction of invasion were both based on similarity to esophageal IPCLs. En-bloc ESD of early-stage ACSCC followed by chemoradiation therapy resulted in a successful treatment and better patient quality of life; it is possible, therefore, that this could become a standard treatment protocol in the future for early-stage ACSCC.

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References

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