Retrospective Study
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Nov 6, 2020; 8(21): 5159-5171
Published online Nov 6, 2020. doi: 10.12998/wjcc.v8.i21.5159
Magnetic resonance imaging findings of carcinoma arising from anal fistula: A retrospective study in a single institution
Xin Zhu, Tian-Shu Zhu, Dan-Dan Ye, Shao-Wei Liu
Xin Zhu, Department of Radiology, The Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing 210029, Jiangsu Province, China
Tian-Shu Zhu, The First Clinical Medical College, Xuzhou Medical University, Xuzhou 221004, Jiangsu Province, China
Dan-Dan Ye, Department of Radiology, Quanzhou Orthopedic-Traumatological Hospital, Quanzhou 362000, Fujian Province, China
Shao-Wei Liu, Department of Radiology, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing 210029, Jiangsu Province, China
Author contributions: Zhu X and Zhu TS contributed equally to this work as first authors; all authors have made an intellectual contribution to the manuscript and approved the submission.
Institutional review board statement: The study was reviewed and approved by the Ethics Committee of The Affiliated Hospital of Nanjing University of Chinese Medicine Nanjing, Jiangsu Province, China.
Conflict-of-interest statement: The authors declare that they have no conflict of interest.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Xin Zhu, MD, Doctor, Department of Radiology, The Affiliated Hospital of Nanjing University of Chinese Medicine, No. 155 Hanzhong Road, Nanjing 210029, Jiangsu Province, China. zhuxin-njcm@njucm.edu.cn
Received: July 19, 2020
Peer-review started: July 6, 2020
First decision: August 8, 2020
Revised: August 18, 2020
Accepted: September 17, 2020
Article in press: September 17, 2020
Published online: November 6, 2020
ARTICLE HIGHLIGHTS
Research background

Magnetic resonance imaging (MRI) is the standard investigation for suspected perianal diseases. This is important to early diagnose carcinoma arising from anal fistula, even if the incidence is low.

Research motivation

To describe and summarize the MRI findings of carcinoma arising from anal fistula.

Research objectives

To summarize the MRI manifestations of carcinoma arising from anal fistula to help improve the ability to diagnose this entity.

Research methods

A retrospective study was performed on ten patients diagnosed with carcinoma arising from anal fistula and confirmed by pathological diagnosis between June 2006 and August 2018. All patients underwent preoperative pelvic MRI. Five patients underwent enhanced MRI scans. Rosser’s criteria were used for diagnosing carcinoma arising from anal fistula. Morphologic features, signal characteristics, fistula between the mass and the anus, contrast enhancement of mass, signal and enhancement of peritumoral areas, and regional lymphadenopathy were assessed.

Research results

Most patients (90%) were older than 50 years. There were eight mucinous adenocarcinomas and two adenocarcinomas. The maximum diameter of the tumors ranged from 3.4 cm to 12.4 cm (median: 4.15 cm; mean: 5.68 cm). Eight patients had a fistula between the mass and the anus. Perirectal or inguinal lymphadenopathy was frequent (7/10).

Most lesions of mucinous adenocarcinoma were multiloculated and cauliflower-like, with a thin capsule and focally unclear boundary. They were markedly hyperintense on fat-suppressed T2WI, slightly hyperintense with focal hyperintense on diffusion-weighted imaging (DWI), and hyperintense with focal hypointensity on apparent diffusion coefficient (ADC) map, with progressive mesh-like contrast enhancement.

Adenocarcinomas had an infiltrative margin without a capsule and appeared heterogeneously hyperintense or slightly hyperintense on fat-suppressed T2WI, hyperintense on DWI, and hypointense on ADC map, with persistent heterogeneous enhancement.

Research conclusions

A negative biopsy does not rule out the diagnosis of cancer, clinicians should be highly suspicious of cancer in patients with chronic perineal fistulas whose symptoms change, and a repeat biopsy should be recommended. The definitive diagnosis of cancer arising from an anal fistula is always challenging. Although the number of cases was inadequate owing to the rarity of the disease, we believe that several characteristic MRI findings could contribute to accurate and timely diagnosis of carcinoma arising from anal fistula in selection of puncture route and screening of high-risk groups.

Research perspectives

Earlier and better identification and monitoring of high-risk groups of carcinoma arising from anal fistula are required.