Hidradenitis Suppurativa and Pediatric Crohn Disease

Crohn disease (CD) is a lifelong, chronic inflammatory disease that primarily affects the gastrointestinal tract; however, CD is a systemic disorder, associated with numerous extraintestinal manifestations including the skin (1). Common dermatologic manifestations of CD include pyoderma gangrenosum, erythema nodosum, and pyostomatitis vegetans; however, there is a paucity of literature on the association of hidradenitis suppurativa (HS) in CD (1). HS, better known as acne inversa, is a chronic inflammatory follicular occlusive disease affecting the skin bearing apocrine sweat glands. HS predominantly affects the axilla and the anogenital regions, although it can occur at various other sites (2). We have performed a retrospective chart review at a single, tertiary pediatric inflammatory bowel disease referral center and identified 7 cases of HS associated with CD. Interestingly, all the cases of HS occurred in females of African American descent. We describe the clinical presentation and medical and surgical outcomes of HS associated with CD. Seven subjects were diagnosed as having HS in our pediatric CD population of 380 patients. Table 1 describes the demographics, clinical manifestations, and treatment responses with tumor necrosis factor (TNF) α inhibitors and eventually the need for surgery in our case series. HS was diagnosed at initial presentation in 3 children and during follow-up in 4 patients, none of whom were prescribed TNF-α inhibitors. Predominant site of involvement were axilla (n = 5) and the perianal region (n = 4). All the subjects had colonic involvement of CD. None had a body mass index >30 and none gave a history of smoking. Severity of the CD did not correlate with the disease progression of HS in any of the children. Although all 7 subjects responded to anti-TNF (infliximab or adalimumab) medications initially, only 3 of them had complete response and resolution of HS. Four of the 7 subjects eventually needed surgical resection of chronic and recurrent HS lesions. Figure 1 shows histology of an excised HS lesion with subcutaneous granuloma, giant cell reaction, and acute/chronic inflammatory changes of the sweat glands.TABLE 1: Summary of the reported patients with Crohn disease and hidradenitis suppurativaFIGURE 1: Section of the skin with hidradenitis suppurativa. A, Skin with underlying intense acute and chronic inflammation (H&E; original magnification ×40). B, Granulomatous inflammation (H&E; original magnification ×400). C, Giant cell reaction (H&E; original magnification ×400). D, Sweat glands with intense acute and chronic inflammation (H&E; original magnification ×400).DISCUSSION Neither the exact pathogenesis of HS nor the association between HS and CD is well described in the literature. Numerous case reports indicate that the HS can be presenting manifestation of CD or can develop during the course of CD (2–5). Both CD and HS are chronic inflammatory diseases with a remitting and relapsing behavior and share a common predilection for the perianal region. Perianal involvement can range from simple tags to complex fistulae. Both HS and CD not only exhibit chronic inflammation but also share histological features of granuloma formation. Both these conditions are also associated with seronegative arthritis (4,6). Given the similarity of many associated features between these 2 conditions, we postulate that HS can be considered as an extraintestinal manifestation of CD. The most striking feature in our case series is that all 7 children were of female sex and of African American descent. This chart review included 380 subjects with CD, and 152 (40%) were categorized as African Americans. It is very interesting that no males or whites were diagnosed as having HS, although our case series is not powered to be considered as a population-based study or to determine the incidence rate. HS can occur in both sexes, although it is 3 times more common in females than males and previous studies suggest no known racial predilection (2,7). Several postulated hypotheses may explain the development of HS. Various studies suggest that the normal rise in androgen levels at the time of puberty trigger the first episode of HS in most patients (2). None of our subjects reported premenstrual flaring of skin lesions or gave a history suggestive of high androgen levels such as recurrent acne, excessive facial, or body hair. HS has been reported to have an autosomal dominant pattern of inheritance in familial cases of HS (7), but all the cases in our series are sporadic. Also, smoking and obesity have been identified as significant risk factors for the development of HS as well as severe disease (7). None of our subjects gave a history of smoking or exposure to second-hand smoke and none of them were obese. Published data suggest efficacy of anti-TNF as treatment for concomitant CD and HS (6,8); however, in our observation, use of anti-TNF for HS resulted in incomplete response needing surgical removal of HS in 4 of 7 cases. A few other studies have noticed similar observations (3,7). We conclude that surgical excision of the skin lesions is needed in many patients with HS, despite the use of anti-TNF. In conclusion, our observations suggest that CD and HS are associated conditions with a common natural history for both. HS could be considered an unusual extraintestinal manifestation of CD, supporting the theory of “auto-intoxication” as proposed previously and not a mere coincidence. Our data suggest that HS is more common in female sex and African descent when associated with CD. Although medical therapy is first reasonable approach, surgical excision is a common requirement and should be considered in cases not responding to medical therapy. Improved recognition of HS and population-based studies is necessary to determine the true incidence of HS in CD.