Hidradenitis suppurativa: A disease of apocrine gland physiology

Hidradenitis suppurativa is a disease affecting the apocrine sweat glands that often results in chronically draining sinus tracks and wounds. Over time, the affected areas become scarred and can be afflicted by contracture or tissue immobility. Physician assistants should possess the knowledge required to diagnose this condition, to initiate conservative medical treatments, and to judge when such management has reached its limitations and a surgical referral is necessary.

The prevalence of hidradenitis suppurativa is approximately 1 in 300 persons,1 with females affected three times as often as males.2 The onset of disease is usually during puberty,3 but it is typically most active between the second and third decades of life and becomes markedly less active in the fifth decade.2 Onset before puberty or after the fifth decade is rare and should prompt the examiner to explore an alternative diagnosis. Hidradenitis suppurativa can significantly impair quality of life because of the pain and discomfort it causes, its limiting effect on daily activities, and the emotional distress suffered by those afflicted.4

In order of prevalence, hidradenitis suppurativa most commonly affects the axillary, inguinal, perianal and perineal, mammary and inframammary, buttock, pubic, chest, scalp, retroauricular, and eyelid areas.2 These areas have large numbers of apocrine glands. 

Etiology Certain factors are known to increase the likelihood that hidradenitis suppurativa will develop. Most clinicians agree that obesity is a predisposing condition;5 smoking has also been implicated as a triggering agent.6 Because of the nearly exclusive onset of hidradenitis suppurativa during puberty, hormonal influences are also thought to be predisposing factors. Lastly, a genetic predisposition has been observed; recent studies have shown that hidradenitis suppurativa may be inherited in an autosomal dominant pattern,7 and its disease gene has been located to chromosome 1p21.1-1q25.3.8 

Pathogenesis The root cause of hidradenitis suppurativa appears to lie in apocrine gland physiology. Unlike the eccrine glands, the apocrine glands are complicated structures composed of a long secretory coil that originates in the subcutaneous tissue, spans the dermis, and empties into a duct that drains into a hair follicle (see Figure 1). The eccrine glands drain directly onto the skin surface.2 Apocrine glands are found most prominently in hair-bearing areas. This physiology led researchers to recognize apocrine gland dysfunction as the most likely cause of hidradenitis suppurativa. 

The proximal inciting event towards the development of hidradenitis suppurativa is obstruction of the follicular duct or of the apocrine gland itself.2,3,9,10 This obstruction leads to dilatation of the duct and secretory stasis, which in turn allows bacteria to multiply within the apocrine gland network, causing infection and possible rupture of the glands. Once the gland has ruptured, the infection spreads into surrounding subcutaneous tissue, which can eventually break down to form one large network of chronically draining abscesses and sinuses.3 At this severe stage, the affected areas can also become fibrous and scarred. 

Unfortunately, there is no specific diagnostic test for hidradenitis suppurativa. Rather, the diagnosis is based solely on the history and physical examination. In most cases, patients present with recurrent, painful skin lesions in the typical distribution that unexpectedly drain purulent discharge in one or several sites. 

Physical examination findings depend on whether the patient presents with acute disease. If the patient is experiencing an acute episode, single or multiple tender erythematous papules or abscesses can be observed. Pus can often be expressed. Depending on the duration of disease, the patient may or may not have skin contractures and areas of focal induration at affected sites. If the disease is in its latent stage, the clinician should note whether these chronic changes are present and should examine other likely areas for evidence of disease. Failure to do so may prevent the examiner from identifying widespread disease when a patient presents with a solitary lesion. If lesions look suspicious for malignancy, a biopsy may be warranted; squamous cell carcinoma has been reported to arise from areas chronically affected by hidradenitis suppurativa.11,12 Patients with Crohn's disease should be evaluated with particular diligence as the prevalence of hidradenitis suppurativa is higher among this subset of patients13 (see Figure 2).

In patients with hidradenitis suppurativa, the choice of treatment should be tailored to the severity of disease. The severity can vary, with limited, local lesions signifying mild hidradenitis suppurativa and severe disease displaying extensive skin involvement with chronically draining abscesses and sinuses. 

For mild to moderate disease, many patients and clinicians choose conservative methods. These measures (warm baths, water therapy, topical cleansing agents, and analgesic agents) may decrease inflammation and discomfort3 but have not been proven to alter the chronicity of the disease.14 Both topical and systemic antibiotics are often used to augment conservative treatments.15 

Several alternative treatment options have been described for hidradenitis suppurativa. Antiandrogen therapies and systemic retinoids, particularly isotretinoin, have had limited benefit.16 Immunosuppressive therapy with systemic and intralesional corticosteroids has shown some advantage in the short term, but relapse is common upon discontinuation.17 Most recently, biological agents engineered to attack tumor necrosis factor-alpha, a proinflammatory cytokine, have produced substantial improvement in symptoms. Infliximab (Remicade) and etanercept (Enbrel) have been studied the most. Treatment with these biologics carries significant risk, however, and no long-term safety data are available.16-19

SURGICAL OPTIONS

Conservative methods are best for those suffering from mild to moderate disease and for those who do not wish to undertake surgical treatments and the morbidities associated with them. For patients who suffer from severe disease or desire more aggressive treatment, surgical options are appropriate.

Incision and drainage is indicated for patients who present with an acutely suppurative lesion. The procedure provides immediate relief and is associated with low morbidity. Unfortunately, the rate of recurrence is high.2

Marsupialization—that is, unroofing of the sinus track—is a more invasive surgical option that involves curetting the sinus tracks and removing the roof of said tracks, while leaving the base intact and allowing the wound to heal by secondary intention. This procedure, too, has been associated with a relatively high rate of recurrence, but it can alleviate acute symptoms and increase the length of time between episodes.2,3 

Local excision with primary closure is best for patients with only a small amount of skin involvement. Here, the affected lesion is removed along with some surrounding tissue, and the skin edges are approximated by primary closure, thus eliminating the repeated dressing changes needed when healing by secondary intention. If the lesion is small, there may be some hope of cure at that site, but overall there is still a relatively high rate of recurrence.3 

Wide excision of the entirety of the affected areas is the only known curative treatment for hidradenitis suppurativa.10 The key to eliminating recurrent disease is to completely excise the affected area with a 1- to 2-cm margin, so that the defect edges are free of disease. It is also important to assure an adequate depth of excision: surgery should extend to the level of the fascia or include at least 0.5 cm of subcutaneous fat to ensure removal of the full apocrine ductwork.3,16 

In wide excision surgery, the question then arises of how to provide adequate skin coverage. Allowing the area to heal by secondary intention after wide excision can be an acceptable option, especially in the perianal areas.3 Application of a split-thickness skin graft can be done either immediately following excision or in a staged fashion. This technique allows coverage of large defects but can be associated with significant wound healing problems at the donor and recipient sites, graft failure, and a poor cosmetic result. Skin grafting areas in and around the anal canal is contraindicated because of the risk that anal stenosis will develop.3 Finally, even with wide excision, complete closure can often be achieved by widely elevating surrounding tissue and advancing that tissue into the defect until coverage is established.

Whichever reconstructive method is used, complete excision of the affected area is the most important consideration for reducing recurrence and providing the patient with a possible cure.9 Recurrence rates are variable with location, with the lowest rates reported in the genital and submammary regions (12%) and the highest rates reported in the inguinal region (21%).14 Higher recurrence rates may be attributed to a broader dispersion of apocrine glands in certain body locations.3 Sometimes further surgery is warranted.

Although definitive treatment can be achieved only by surgical intervention, many patients choose to postpone surgery until they have exhausted more conservative options. Therefore, it is important for PAs of all disciplines to be familiar with the clinical presentation and various treatment options for hidradenitis suppurativa to assist with the appropriate care for this problematic condition. When the disease progresses into its severe stages, appropriate surgical referral and treatment should be sought. JAAPA

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Steve Wilson, PA-C, department editor

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REFERENCES 

1. Fitzsimmons JS, Guilbert PR, Fitzsimmons EM. Evidence of genetic factors in hidradenitis suppurativa. Br J Dermatol. 1985;113(1):1-8.

2. Slade DEM, Powell BW, Mortimer PS. Hidradenitis suppurativa: pathogenesis and management. Br J Plast Surg. 2003;56(5):451-461.

3. Mitchell KM, Beck DE. Hidradenitis suppurativa. Surg Clin North Am. 2002;82(6):1187-1197.

4. Wolkenstein P, Loundou A, Barrau K, et al. Quality of life impairment in hidradenitis suppurativa: a study of 61 cases. J Am Acad Dermatol. 2007;56(4):621-623.

5. Yosipovitch G, DeVore A, Dawn A. Obesity and the skin: skin physiology and skin manifestations of obesity. J Am Acad Dermatol. 2007;56(6):901-916.

6. Konig A, Lehmann C, Rompel R, Happle R. Cigarette smoking as a triggering factor of hidradenitis suppurativa. Dermatology. 1999;198(3):261-264.

7. Von Der Werth JM, Williams HC, Raeburn JA. The clinical genetics of hidradenitis suppurativa revisited. Br J Dermatol. 2000;142(5):947-953.

8. Gao M, Wang P-G, Cui Y, et al. Inversa acne (hidradenitis suppurativa): a case report and identification of the locus at chromosome 1p21.1-1q25.3. J Inv Dermatol. 2006;126(6):1302-1306.

9. Tanaka A, Hatoko M, Tada H, et al. Experience with surgical treatment of hidradenitis suppurativa. Ann Plast Surg. 2001;47(6):636-642.

10. Kagan RJ, Yakuboff KP, Warner P, Warden GD. Surgical treatment of hidradenitis suppurativa: a 10-year experience. Surgery. 2005;138(4):734-740.

11. Rosenzweig LB, Brett AS, Lefaivre J-F, Vantersteenhoven JJ. Hidradenitis suppurativa complicated by squamous cell carcinoma and paraneoplastic neuropathy. Am J Med Sci. 2005;329(3): 150-152.

12. Maclean GM, Coleman DJ. Three fatal cases of squamous cell carcinoma arising in chronic perineal hidradenitis suppurativa. Ann R Coll Surg Engl. 2007;89(7):709-712.

13. Ostlere LS, Langtry JAA, Mortimer PS, Staughton RCD. Hidradenitis suppurativa in Crohn's disease. Br J Dermatol. 1991;125(4):384-386.

14. Bohn J, Svensson H. Surgical treatment of hidradenitis suppurativa. Scand J Plast Reconstr Surg Hand Surg. 2001;35(3):305-309.

15. Jemec GBE, Wendelboe P. Topical clindamycin versus systemic tetracycline in the treatment of hidradenitis suppurativa. J Am Acad Dermatol. 1998;39(6):971-974.

16. Lee RA, Yoon A, Kist J. Hidradenitis suppurativa: an update. Adv Derm. 2007;23:289-306.

17. Lam J, Krakowski AC, Friedlander SF. Hidradenitis suppurativa (acne inversa): management of a recalcitrant disease. Ped Dermatol. 2007;24(5):465-473.

18. Fernandez-Vozmediano JM, Armario-Hita JC. Infliximab for the treatment of hidradenitis suppurativa. Dermatology. 2007;215(1):41-44.

19. Cusack C, Buckley C. Etanercept: effective in the management of hidradenitis suppurativa. Br J Dermatol. 2006;154(4):726-729.