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CC BY 4.0 · Endoscopy 2025; 57(S 01): E1286-E1287
DOI: 10.1055/a-2721-9065
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First case of hemorrhoidal carcinoma in a fistulotomy scar: successful per-anal endoscopic myectomy despite severe fibrosis

Authors

  • Xiaona Shao

    1   Department of Gastroenterology, Ningbo Medical Center Lihuili Hospital, Ningbo, China (Ringgold ID: RIN74634)

  • Naoya Toyoshima

    2   Department of Endoscopy, National Cancer Center Hospital, Tokyo, Japan (Ringgold ID: RIN68380)

  • Toshihiro Haga

    3   Department of Pathology, National Cancer Center Hospital, Tokyo, Japan (Ringgold ID: RIN13874)

  • Mitsunori Kusuhara 

    4   Department of Gastroenterology and Hepatology, Kyorin University, Tokyo, Japan (Ringgold ID: RIN12912)

  • Yukihide Kanemitsu

    5   Department of Colorectal Surgery, National Cancer Center Hospital, Tokyo, Japan

  • Jianwei Shen

    1   Department of Gastroenterology, Ningbo Medical Center Lihuili Hospital, Ningbo, China (Ringgold ID: RIN74634)

  • Yutaka Saito 

    2   Department of Endoscopy, National Cancer Center Hospital, Tokyo, Japan (Ringgold ID: RIN68380)

This case report was supported by the programs for Bringing the gap between R&d and the Ideal society and Generating Economic and social value (BRIDGE).
This case report was supported by the NCC MIRAI project.
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Rectal endoscopic submucosal dissection (ESD) offers a minimally invasive, function-preserving alternative to radical surgery, allowing en bloc resection and precise histopathological assessment. However, severe submucosal fibrosis with muscle retraction can significantly hinder complete resection. Following Rahni et al.’s pioneering description of per-anal endoscopic myectomy (PAEM) for R0 resection of such lesions [1], we report the first case of hemorrhoidal carcinoma arising in a post-fistulotomy scar successfully treated using this technique.

A 70-year-old man with a history of anal fistula surgery presented with occult blood in stool. Colonoscopy revealed a 10-mm type 0-Is lesion (1 cm from the dentate line) with the JNET 2B/type IV pit pattern ([Fig. 1]). Initial ESD at the referring hospital was aborted due to suspected muscular invasion (biopsy: well-differentiated adenocarcinoma). At our center, image-enhanced endoscopy confirmed Tis-T1a carcinoma (JNET 2B/type IV) despite marked fibrosis ([Fig. 2]). PAEM achieved en bloc R0 resection ([Fig. 3]); histopathology confirmed hemorrhoidal adenocarcinoma, an exceedingly rare malignancy ([Fig. 4]). No recurrence was noted at 6-month follow-up ([Fig. 5]).

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Fig. 1 Endoscopic image (Rb): the 10-mm 0-Is lesion near anal verge (white arrow: lesion; black arrow: scar).
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Fig. 2 Indigo carmine dyeing shows the flat elevated lesion in the post-fistulotomy scar and assessed as Tis-T1a.
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Fig. 3 En bloc resection of the fibrotic lesion via PAEM. PAEM, per-anal endoscopic myectomy.
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Fig. 4 11 × 10 mm specimen (pTis, Vienna 4.2) showing mucosal adenocarcinoma involving fistula orifice.
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Fig. 5 Mucosal healing at 6-month follow-up; no recurrence.

This case highlights PAEM’s safety and efficacy for severely fibrotic lesions ([Video 1]). Fistula-associated carcinomas occur in ~1% of chronic anal fistulas [2], often with delayed diagnosis. To our knowledge, this is the first reported case of endoscopic resection of hemorrhoidal carcinoma arising from a fistulous tract.

PAEM employs dual-tunnel circumferential dissection to isolate fibrotic lesions, transecting the inner circular muscle while preserving the outer longitudinal muscle for R0 resection. PAEM, per-anal endoscopic myectomy.Video 1

PAEM enabled (1) complete resection, including fistula-involved tissue and (2) dissection while avoiding submucosal fibrosis. Key points: (1) magnified endoscopy with pit pattern analysis is essential for accurate staging in distorted anatomy; (2) multidisciplinary management is crucial; (3) chronic anorectal wounds warrant surveillance due to malignant potential.

PAEM is an effective salvage strategy for ESD-ineligible fibrotic lesions [3].

Endoscopy_UCTN_Code_CCL_1AD_2AB

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Conflict of Interest

The authors declare that they have no conflict of interest.


Correspondence

Yutaka Saito, MD, PhD
Department of Endoscopy, National Cancer Center Hospital
5-1-1 Tsukiji, Chuo-ku
Tokyo 104-0045
Japan   

Publication History

Article published online:
14 November 2025

© 2025. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/).

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Zoom
Fig. 1 Endoscopic image (Rb): the 10-mm 0-Is lesion near anal verge (white arrow: lesion; black arrow: scar).
Zoom
Fig. 2 Indigo carmine dyeing shows the flat elevated lesion in the post-fistulotomy scar and assessed as Tis-T1a.
Zoom
Fig. 3 En bloc resection of the fibrotic lesion via PAEM. PAEM, per-anal endoscopic myectomy.
Zoom
Fig. 4 11 × 10 mm specimen (pTis, Vienna 4.2) showing mucosal adenocarcinoma involving fistula orifice.
Zoom
Fig. 5 Mucosal healing at 6-month follow-up; no recurrence.