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Review
. 2025 Jun 27;27(1):46.
doi: 10.1007/s11894-025-00998-0.

A Guide Through the Tunnel: Updates in the Approach to Classification and Management of Perianal Fistulizing Crohn's Disease

WonKyung J Cho  1 , Serre-Yu Wong  2
Affiliations
Review

A Guide Through the Tunnel: Updates in the Approach to Classification and Management of Perianal Fistulizing Crohn's Disease

WonKyung J Cho et al. Curr Gastroenterol Rep. .

Abstract

Purpose of review: Perianal fistulizing Crohn's disease (PFCD) is a severe and debilitating phenotype of Crohn's disease that presents significant clinical and therapeutic challenges. This review aims to outline a practical approach to classification and management, emphasizing the utility of the TOpClass system.

Recent findings: The TOpClass classification incorporates clinical and anatomic characteristics to assess severity, treatment options, and patient-clinician goals. Post-hoc analyses from clinical trials for the Janus kinase inhibitor Upadacitinib and emerging data on IL-23 receptor antagonists suggest potential roles beyond anti-TNFs, while the broader use of mesenchymal stem cell therapy remains limited due to inconsistent efficacy. Fistula conditioning with curettage and internal opening closure-an underutilized technique-alongside adjunctive therapies such as hyperbaric oxygen therapy (HBOT), has shown promise in promoting wound healing in select patients. The TOpClass classification, by integrating patient-centered factors and multidisciplinary management, offers a comprehensive and adaptable framework for PFCD, addressing key gaps in treatment planning, standardization, and research. The classification will enable tailored, evidence-based care across the disease spectrum.

Keywords: Crohn’s disease; Perianal fistula; Perianal fistulizing Crohn’s disease; TOpClass classification.

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Conflict of interest statement

Declarations. Competing Interests: Author SYW reports research contract with Takeda/Trinetx; advisory board - Bristol Myers Squibb; and support - Eli Lilly and Company.

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