What causes hidradenitis suppurativa?

Abstract:  Hidradenitis suppurativa (HS) – a rather common, very chronic and debilitating inflammatory skin appendage disorder with a notoriously underestimated burden of disease – has long been a playground for the high priests of nomenclature: Ask a bunch of eminent dermatologists and skin pathologists to publicly share their thoughts on what causes HS, and they will soon get entrenched in a heated debate on whether this historical term is a despicable misnomer. Fortunately, the recently founded Hidradenitis Suppurativa Foundation (HSF; http://www.hs-foundation.org ), to which EXP DERMATOL serves as home journal, has broken with this unproductive tradition and has encouraged publication of the current CONTROVERSIES feature. This is exclusively devoted to discussing the pathobiology of this chronic neutrophilic folliculitis of unknown origin. Although traces of terminological bickering remain visible, it does the HS experts in our virtual debate room credit that they engage in a constructive and comprehensive dissection of potential pathogenesis pathways that may culminate in the clinical picture we know under the competing terms HS or acne inversa. These experts sketch more often complementary than mutually exclusive pathogenesis scenarios, and the outlines of a conceivable consensus on the many open pathobiology questions begin to emerge in these CONTROVERSIES. Hopefully, this heralds a welcome new tradition: to get to the molecular heart of HS pathogenesis, which can only be achieved by a renaissance of solid basic HS research, as the key to developing more effective HS therapy.     

Are dissecting cellulitis and hidradenitis suppurativa different diseases?

Although dissecting cellulitis (DC) and hidradenitis suppurativa (HS) are classified separately, they share many clinical, dermatoscopic, pathogenetic, and histologic aspects, as well as therapeutic options. The association between DC, HS, and acne conglobata represents the follicular occlusion triad or follicular occlusion tetrad, which may include a pilonidal sinus. DC, also known as “folliculitis et perifolliculitis capitis abscendes et suffoidens,” is classified as a secondary cicatricial and neutrophilic alopecia. It occurs with perifolliculitis of the scalp, dermal abscesses, sinus tract development, and secondary scarring alopecia. HS, sometimes known as acne inversa, is a chronic relapsing inflammatory disease afflicting apocrine gland–rich areas of the body with painful nodules and abscesses, sinus tracts, and scarring. Given the overlap between the clinical features and the pathogenesis of DC and HS, it would be more appropriate to consider these conditions as two different localizations of the same disease rather than two different pathologies, being a follicular occlusion disease occurring on the scalp and on the apocrine gland–rich areas of the body.     

Could isotretinoin flare hidradenitis suppurativa? A case series

We report eight cases of patients with severe acne who were treated with isotretinoin and developed painful nodules in the axillae and groin, consistent with hidradenitis suppurativa (HS). The pathogenesis of HS is still not completely understood; recent research from a study in 2011 of biopsies from HS lesions showed a reduction or absence of sebaceous glands compared with normal skin in patients with HS, with the report suggesting that this contributes to the pathogenesis of the disease. Interestingly, the main effect of isotretinoin is to decrease the size and action of sebaceous glands, so hypothetically, as isotretinoin acts by reducing the sebaceous glands further it could potentially aggravate HS. Our experience has instilled caution in our prescribing of isotretinoin, and we question patients, particularly those with acne conglobata, about symptoms of HS prior to and during treatment.     

What causes hidradenitis suppurativa ?—15 years after

The 14 authors of the first review article on hidradenitis suppurativa (HS) pathogenesis published 2008 in EXPERIMENTAL DERMATOLOGY cumulating from the 1st International Hidradenitis Suppurativa Research Symposium held March 30–April 2, 2006 in Dessau, Germany with 33 participants were prophetic when they wrote “Hopefully, this heralds a welcome new tradition: to get to the molecular heart of HS pathogenesis, which can only be achieved by a renaissance of solid basic HS research, as the key to developing more effective HS therapy.” (Kurzen et al. What causes hidradenitis suppurativa? Exp Dermatol 2008;17:455). Fifteen years later, there is no doubt that the desired renaissance of solid basic HS research is progressing with rapid steps and that HS has developed deep roots among inflammatory diseases in Dermatology and beyond, recognized as “the only inflammatory skin disease than can be healed”. This anniversary article of 43 research-performing authors from all around the globe in the official journal of the European Hidradenitis Suppurativa Foundation e.V. (EHSF e.V.) and the Hidradenitis Suppurativa Foundation, Inc (HSF USA) summarizes the evidence of the intense HS clinical and experimental research during the last 15 years in all aspects of the disease and provides information of the developments to come in the near future.     

Is mechanical stress an important pathogenic factor in hidradenitis suppurativa?

Hidradenitis suppurativa (HS) is a chronic of recurrent, inflammatory, follicular disease that usually presents after puberty with painful deep-seated, inflamed lesions in the inverse skin areas of the body. It has been hypothesized that mechanical pressure or friction is a risk factor for HS. We describe the case of a man with a lower leg amputation who presented HS-like lesions on his leg stump after wearing a leg prosthesis. Although pilonidal sinus-like disease could not be excluded, we diagnosed him with HS-like lesions, induced by prosthesis-related friction. We argue that this case supports the concept that mechanical friction and a warm humid microclimate by occlusion contribute to HS development.     

Two diseases one remedy? Systemic amyloidosis secondary to hidradenitis suppurativa: Treatment with infliximab

Hidradenitis suppurativa, known as acne inversa, is a relapsing and chronic inflammatory skin disease affecting the skin folds. During the chronic course of the disease many local complications like fistulae to other tissues or systemic complications including anemia, secondary amyloidosis, lymphedema, nephrotic syndrome, artropathy may take place. Amyloid A amyloidosis is a rare complication of hidradenitis suppurativa, which has been described in a limited number of case reports. Herein, we present such a patient that had developed AA amyloidosis during the course of hidradenitis suppurativa. Both AA amyloidosis and hidradenitis suppurativa have responded to infliximab therapy which was shown by clinical recovery and by the improvement in renal functions.