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 Table of Contents  
Year : 2020  |  Volume : 9  |  Issue : 1  |  Page : 7-9

Is routine pathological analysis of perianal fistula specimen necessary in diagnosis of crohn's disease?

1 University Hospital Geelong, Epworth Hospital Geelong, Australia
2 Eastern Health, Faculty of Medicine, Dentistry and Health Science, University of Melbourne, Australia
3 Eastern Health, Eastern Clinical School, Monash University, Australia

Date of Submission20-Nov-2019
Date of Decision14-Dec-2019
Date of Acceptance06-Jan-2020
Date of Web Publication28-Mar-2020

Correspondence Address:
Dr. Steve Y. C Lau
University Hospital Geelong, Bellerine Street, Geelong, 3220, Victoria
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/WJCS.WJCS_25_19

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Background: Crohn's disease causes recurrent and complex perianal fistulas. Although the prevalence of it is up to 30%, the common cause of perianal fistula is thought to be the crypto-glandular theory. Surgeons send perianal fistula specimens for histopathological analysis; however, it is unclear whether such practices should be performed routinely. Objective: Evaluating the utility of routine histopathology on perianal fistula specimens during surgery to exclude the diagnosis of Crohn's disease. Design: Multicenter retrospective study was conducted from January 2012 to October 2018 on patients who underwent surgery for perianal fistula and specimen sent for histology. Setting: Metropolitan tertiary referral center in Melbourne, Australia. Patients and Methods: 105 patients who underwent 124 anal fistula procedures and their perianal fistula specimens sent for histopathological analysis were selected from the medical database. Medical and pathology reports were analyzed and data were reviewed by a second author for consistency. Sample Size: 105 patients, 124 procedures. Main Outcome Measures: Histopathological results suspicious for Crohn's disease and endoscopic examination results to confirm Crohn's disease. Results: 41 together, 124 perianal fistula specimens were collected from 105 patients. The male to female ratio was 2.9:1 and the average age was 43.6 years. Nonspecific inflammation was seen in 121 (97.5%) specimens. Three specimens had granulomatous inflammation of which, only two (1.6%) had Crohn's disease confirmed on endoscopic biopsy of the terminal ileum. In 15 patients with Crohn's disease, none of the 19 specimens sent for histology demonstrated histopathological features of Crohn's disease. Conclusion: Routine histopathological analyses of perianal fistula specimens provide limited clinical value. Clinicians should selectively send specimens for histopathological analysis to limit the use of resources. Limitations: Retrospective study. Not all perianal fistula specimens were routinely sent for the analysis. Data prior to 2012 was not collected as we are limited by an electronic database which was commenced in 2012. Conflict of Interest: None.

Keywords: Crohn's disease, fistula-in-ano, perianal fistula

How to cite this article:
Lau SY, Yu CC, Ng SC, Chandra R. Is routine pathological analysis of perianal fistula specimen necessary in diagnosis of crohn's disease?. World J Colorectal Surg 2020;9:7-9

How to cite this URL:
Lau SY, Yu CC, Ng SC, Chandra R. Is routine pathological analysis of perianal fistula specimen necessary in diagnosis of crohn's disease?. World J Colorectal Surg [serial online] 2020 [cited 2021 Sep 29];9:7-9. Available from: https://www.wjcs.us.com/text.asp?2020/9/1/7/281589

Steve Lau and Casey Yu both contributed equally to article as co-authors.

  Introduction Top

Crohn's disease is a chronic inflammatory disease characterized by transmural inflammation that disrupts the mucosal integrity of the anal canal and causes complications such as perianal abscesses and complex perianal fistulas. This results in significant disease burden, diminishing patients' quality of life, and increasing the usage of health resources. Although the prevalence of perianal fistulas in Crohn's patients is high (30% of patients with Crohn's disease develop perianal fistulas[1]), the commonest cause for most fistulas is Eisenhammer and Parks' crypto-glandular theory.[2] Other common causes include tuberculosis, anal fissures, malignancies, and iatrogenic injury from surgery.[3]

Although surgeons send histopathology specimens of perianal fistulas while performing an examination under anesthetics (EUA) to exclude etiologies such as Crohn's disease or malignancy, it is unclear if this practice should be carried out selectively or routinely. Without objective data and with the high cost of health care, it is important to investigate further if this analysis is necessary. This article assesses the utility of submitting fistulotomy specimens for histopathological review to exclude the diagnosis of Crohn's disease.

  Patients and Methods Top

A multicenter retrospective study was conducted from January 2012 to October 2018. Patients of ages between 18 and 80, who had surgery for a perianal fistula with histopathology specimen analysis, were identified from the electronic medical records (EMR). The initial search for the diagnosis of anal fistula had included subgroup diagnoses such as acute anal fissure; chronic anal fissure; anal fissure, unspecified; rectal fistula; and anorectal fistula. Case files, operation notes, and pathology reports were screened for the following:

  1. Those who have undergone surgical intervention,
  2. Those who have had pathology specimens sent from surgery; and,
  3. Any known diagnosis of Crohn's disease before or after the surgery.

Incorrectly labeled patients with anal polyps or anal fissures were excluded. Patients who had undertaken multiple procedures for anal fistulae were assessed separately for each encounter if their pathology samples were submitted for histopathology.

The reports included in this study were reviewed to identify characteristics of Crohn's disease; including features such as noncaseating granulomas, transmural inflammation, and deep ulceration. The relevant case files were reviewed to determine whether investigations to confirm Crohn's disease and exclude tuberculosis had been performed. Medical records of patients who had their fistula samples sent for histopathological review were analyzed in greater detail. The data have also been reviewed by the second author.

The costs of the specimen examined were revealed by a pathologist and with reference to the Australian Medicare benefits schedule from 2014. The approval of the Office of Research and Ethics was taken for this study.

  Results Top

One hundred twenty-four cases of anal fistulas from 105 patients were identified from January 2012 to October 2018 from medical records and histopathology reports. Each of these 124 cases had surgical specimens sent for pathology review.

Our cohort included 78 males and 27 females; male to female ratio was 2.9:1. The average age was 43.6 years with a range of 18–78 years. Fifteen patients had multiple surgeries had their specimens sent for analysis after each surgery (11 with two operations and four with three operations), all were men.

Two patients had histology specimens revealing suspicious features suggestive of Crohn's disease. Both have had a colonoscopic biopsy of colon and terminal ileum, which confirmed Crohn's disease. One patient demonstrated nonspecific chronic granulomatous inflammation, which ultimately did not confirm Crohn's disease. Fifteen patients had known diagnoses of Crohn's disease prior to their surgery. A total of 19 fistulotomy specimens were sent, however, none of the specimens demonstrated any features of Crohn's disease.

  Discussion Top

Routine histopathology analysis of surgical specimens provides diagnostic information, prognostication, or help guide further management of a specific condition.[4] While this causes little harm to the patient, the increasing burden on the health care system worldwide has brought into the question the cost-effectiveness of routine analysis of all surgical specimens.[5] Despite its commonality, only a few studies have been performed to assess the utility of routine histopathological examination of perianal fistula.[6],[7]

The average age and gender predisposition to perianal fistula are consistent with other studies in the literature.[6],[7] Three patients (2.8%) had a histological finding of noncaseating granulomatous inflammation, of which two had colonoscopic biopsies confirming Crohn's disease. Interestingly, in 15 patients with a known diagnosis of Crohn's disease, the characteristic finding of granulomatous inflammation was not observed. In contrast to other studies,[6],[7] none of the specimens had caseating granulomas. This leads to further investigations to exclude tuberculosis. This is probably reflective of our patient population in Australia where tuberculosis is not endemic.

In the literature, granulomas were seen in 7–17.5% of perianal fistula specimens compared to 2.4% (3/124) of specimens in our study.[6],[7] This difference may be attributed to the higher number of specimens with caseating granulomas where tuberculosis is endemic. Malignant transformation of chronic perianal fistula has been reported in a few case reports, but none in this study.[8] A study in the Netherlands of 2,324 patients with fistulas over a 17-year period showed only four patients with malignancy arising from a chronic fistula, and all had Crohn's disease. The median age of diagnosis was 46.2 years, and adenocarcinoma developed on average 22 years after the diagnosis of Crohn's disease and 9 years after diagnosis of a fistula tract.[8] While this is an important diagnosis, it is rare. We advocate sending large fistula specimens for histology of Crohn's patients with the refractory perianal disease and performing macrobiopsies on suspicious lesions. Surgeons need to be extra vigilant as smaller biopsies of nonrepresentative samples often are falsely reassuring, resulting in diagnostic delay and poor prognosis.

This is the second-largest study performed to assess the value of routine histopathological analysis of perianal fistulas. Patients with fistulas showing noncaseating granulomas underwent further investigations to confirm Crohn's disease. Although the presence of noncaseating granulomas is suggestive of Crohn's disease and may trigger further investigations, patients with Crohn's disease did not show granulomatous inflammation on histology. A good index of suspicion based on the patient's clinical presentation and history is still key in the diagnosis of Crohn's disease. In an Australian population where tuberculosis is not endemic, there is a very low yield of routine analysis of fistulas for tuberculosis.

The limitations of our study include its retrospective nature and that not all fistula specimens were routinely analyzed. The decision to send specimens for histopathological examination was left to the surgeons. The dataset available for analyses was also limited by the electronic database, which only commenced in 2012. Nevertheless, we analyzed all patient medical records in detail and the data were reviewed by a second author to reduce error.

In conclusion, routine histopathological analysis of perianal fistula specimens has limited clinical value in diagnosing Crohn's disease and should be performed in the appropriate clinical setting. Further investigations are required to confirm the diagnosis of Crohn's disease. Histopathological analysis of perianal fistula specimens alone costs AUD 10793.75 excluding any unnecessary tests performed based on histology findings. In the era where health care systems are burdened with increasing costs, the appropriate use of pathological analysis of surgical specimens may reduce the costs and divert limited resources to areas of need.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Panes J, Reinisch W, Rupniewska E, Khan S, Forns J, Khalid JM, et al. Burden and outcomes for complex perianal fistulas in Crohn's disease: World J Gastroenterol 2018;24:4821-34.  Back to cited text no. 1
Eisenhammer S. A new approach to the anorectal fistulous abscess based on the high intermuscular lesion. Surg Gynecol Obstet 1958;106:595-9.  Back to cited text no. 2
Michalopoulos A, Papadopoulos V, Tziris N, Apostolidis S. Perianal fistulas. Tech Coloproctol 2010;14:15-7.  Back to cited text no. 3
Lohsiriwat V, Vongjirad A, Lohsiriwat D. Value of routine histopathologic examination of three common surgical specimens: Appendix, gallbladder, and hemorrhoid. World J Surg 2009;33:2189-93.  Back to cited text no. 4
Matthyssens LE, Ziol M, Barrat C, Champault GG. Routine surgical pathology in general surgery. Br J Surg 2006;93:362-8.  Back to cited text no. 5
Wijekoon NS, Samarasekera DN. The value of routine histopathological analysis in patients with fistula in-ano. Colorectal Dis 2010;12:94-6.  Back to cited text no. 6
Bheema Rao G, Srivastava V. Histopathological study of fistula in ano and its relevance. J Diag Pathol Oncol 2018;3:101-3.  Back to cited text no. 7
Baars JE, Kuipers EJ, Dijkstra G, Hommes DW, de Jong DJ, Stokkers PC, et al. Malignant transformation of perianal and enterocutaneous fistulas is rare: Results of 17 years of follow-up from The Netherlands. Scand J Gastroenterol 2011;46:319-25.  Back to cited text no. 8


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