Topic Highlight
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. May 28, 2016; 22(20): 4802-4811
Published online May 28, 2016. doi: 10.3748/wjg.v22.i20.4802
Hydradenitis suppurativa and inflammatory bowel disease: An unusual, but existing association
Mariabeatrice Principi, Nicoletta Cassano, Antonella Contaldo, Andrea Iannone, Giuseppe Losurdo, Michele Barone, Mario Mastrolonardo, Gino Antonio Vena, Enzo Ierardi, Alfredo Di Leo
Mariabeatrice Principi, Antonella Contaldo, Andrea Iannone, Giuseppe Losurdo, Michele Barone, Enzo Ierardi, Alfredo Di Leo, Gastroenterology Section, Department of Emergency and Organ Transplantation, University of Bari, 70124 Bari, Italy
Nicoletta Cassano, Gino Antonio Vena, Dermatology and Venereology Private Practice, 70124 Bari/76121 Barletta, Italy
Mario Mastrolonardo, Dermatology Unit, Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy
Author contributions: Principi M, Ierardi E and Di Leo A designed the study, revised the manuscript and approved the final version; Cassano N, Contaldo A, Iannone A, Losurdo G and Mastrolonardo M collected the data and wrote the manuscript; Barone M and Vena GA revised the final version before approval.
Conflict-of-interest statement: No conflict of interest is declared by authors.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (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:
Correspondence to: Dr. Enzo Ierardi, Professor, Gastroenterology Section, Department of Emergency and Organ Transplantation, University of Bari, 70124 Bari, Italy.
Telephone: +39-80-5594034 Fax: +39-80-5593088
Received: March 18, 2016
Peer-review started: March 21, 2016
First decision: March 31, 2016
Revised: April 11, 2016
Accepted: May 4, 2016
Article in press: May 4, 2016
Published online: May 28, 2016

Inflammatory bowel disease (IBD) could be associated with several extra-intestinal manifestations (EIMs) involving musculoskeletal, hepatopancreatobiliary, ocular, renal, and pulmonary systems, as well as the skin. In the last years, hidradenitis suppurativa (HS) is acquiring an increasing interest. IBD, especially Crohn’s disease (CD), is among the most reported associated diseases in HS patients. The aim of this paper is to give a brief overview of data showing a possible epidemiologic and pathogenetic association between IBD and HS. We performed a pooled-data analysis of four studies and pooled prevalence of HS in IBD patients was 12.8%, with a 95%CI of 11.7%-13.9%. HS was present in 17.3% of subjects with CD (95%CI: 15.5%-19.1%) and in 8.5% of UC patients (95%CI: 7.0%-9.9%). Some items, especially altered immune imbalance, are generally involved in IBD pathogenesis as well as invoked by HS. Smoking is one of the most relevant risk factors for both disorders, representing a predictor of their severity, despite, actually, there being a lack of studies analyzing a possible shared pathway. A role for inheritance in HS and CD pathogenesis has been supposed. Despite a genetic susceptibility having been demonstrated for both diseases, further studies are needed to investigate a genetic mutual route. Although the pathogenesis of IBD and HS is generally linked to alterations of the immune response, recent findings suggest a role for intestinal and skin microbiota, respectively. In detail, the frequent finding of Staphylococcus aureus and coagulase-negative staphylococci on HS cutaneous lesions suggests a bacterial involvement in disease pathogenesis. Moreover, microflora varies in the different cutaneous regions of the body and, consequently, two different profiles of HS patients have been identified on these bases. On the other hand, it is well-known that intestinal microbiota may be considered as “the explosive mixture” at the origin of IBD despite the exact relationship having not been completely clarified yet. A better comprehension of the role that some bacterial species play in the IBD pathogenesis may be essential to develop appropriate management strategies in the near future. A final point is represented by some similarities in the therapeutic management of HS and IBD, since they may be controlled by immunomodulatory drugs. In conclusion, an unregulated inflammation may cause the lesions typical of both HS and IBD, particularly when they coexist. However, this is still a largely unexplored field.

Keywords: Hydradenitis suppurativa, Inflammatory bowel disease, Crohn’s disease, Ulcerative colitis, Intestinal microbiota, Skin microbiota, Immunosuppressant drugs

Core tip: The present topic outlines the main data regarding a possible association between hydradenitis suppurativa and inflammatory bowel disease with particular attention to epidemiology, etiopathogenetic factors, genetic susceptibility, intestinal/skin microbiota and therapeutic analogies. Finally, an unregulated inflammation leading to microscopic granulomatous wounds may cause the lesions typical of both diseases, particularly when they coexist. However, this is still a largely unexplored field, and further studies are required.