Introduction Hidradenitis suppurativa is a chronic inflammatory disease of apocrine gland-bearing skin. It has a predilection for the ano-genital skin and is characterised clinically by inflammatory abscesses and sinus tract formation. Clinically, the condition can mimic cutaneous Crohn's disease, and furthermore it may co-exist with Crohn's disease.1 MRI is often used to assess perianal Crohn's disease and has been comprehensively described in the literature, however to date, there has only been one case report to describe the MRI features of perianal hidradenitis suppurativa.2
Methods The electronic patient records, and radiology and inflammatory bowel disease databases were searched for patients with hidradenitis suppurativa who had undergone short-tau inversion recovery (STIR) MR imaging to define disease severity, assess for fistulating disease and exclude Crohn's disease, between 2005 and 2012.
Results A total of 188 patients with hidradenitis suppurativa were identified (129 female, six with concomitant IBD), of whom 18 (15 male, three with comcomitant IBD) had undergone perianal MRI. On baseline MRI, multiple tracts were typically seen in the natal cleft (15/18), the perianal (11/18), the perineal (10/18) and glutaeal (8/18) regions. Abscesses were most commonly glutaeal (3/18). The overall pattern of disease was distinct to that seen in Crohn's disease, with multiple sinus tracts that were superficial in nature in the majority of patients with hidradentis suppurativa, compared to perianal Crohn's disease where tracts are usually centred on the anal sphincter complex.
Conclusion The use of STIR MRI can help define extent of perianal disease in hidradenitis suppurativa, and typically shows a different involvement compared to Crohn's disease, allowing distinction between the two, and thus appropriate management.
Competing interests None declared.
References 1. van der Zee HH, van der Woude CJ, Florencia EF, et al. Hidradenitis suppurativa and inflammatory bowel disease: are they associated? Results of a pilot study. Br J Dermatol 2010;162:195–7.
2. Kelly AM, Cronin P. MRI features of hidradenitis suppurativa and review of the literature. AJR Am J Roentgenol 2005;185:1201–4.