Hidradenitis suppurativa (HS) is a chronic inflammatory skin disorder characterized by painful nodules and abscesses that reoccur and can cause irreversible scarring.1,2 Hidradenitis suppurativa preferentially affects the intertriginous regions of the body such as the axillary, inguinal, and perianal areas.3

Hidradenitis suppurativa is a relatively common condition. In the US, data from a large retrospective cohort analysis found a 1-year incidence of 11.4 cases per 100,000 population (95% CI, 11.1-11.8).4 Though the pathogenesis and etiology of HS are not fully understood, it is believed that a mixture of genetic and environmental factors trigger the onset of this disease.2,3,5

Previously, it was thought that HS was an infection of apocrine sweat glands.3 However, recent research suggests that HS is caused by inflammation due to dysregulated skin immunity surrounding hair follicles in intertriginous areas.3,5 This perifollicular inflammation leads to hyperkeratosis and occlusion of the affected hair follicles.3 Accumulation of sebum and debris in the surrounding dermis initiates the inflammatory cascade leading to painful and inflamed nodules.3 Prolonged inflammation in the area results in the formation of abscesses and ultimately sinus tracts that cause bacterial colonization, suppuration, and scarring.3


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Risk Factors

Hidradenitis suppurativa predominately affects women with a female to male ratio of 3:1 and an increased incidence of the disease is found among Black patients.3,5 Hidradenitis suppurativa has a genetic component to development; 30% to 40% of patients with HS have a positive family history of the disease.2 Environmental risk factors play a pivotal part in disease progression and severity with obesity and cigarette smoking as the main contributors.2 Increased adipose tissue stimulates a proinflammatory environment as well as increases the friction in intertriginous areas. This results in increased follicular hyperkeratinization and occlusion in overweight HS patients.3 Additionally, a strong correlation exists between smoking and HS. In a population-based study, approximately 70% of patients with HS reported being current or former smokers.6

Diagnosis

Hidradenitis suppurativa diagnosis most commonly occurs during the second decade of life.3 Cases in prepubertal children are rare.7 However, cases have been diagnosed as early as age 6 years.7 The disease progression of HS is cyclical with periods of inflammation and remission.3 The inflammatory activity typically peaks during the third and fourth decades of life and then usually resolves.3 For women, HS typically resolves after menopause.3

The majority of HS patients have mild to moderate disease; however, 4% to 22% of patients report severe disease progression and burden.3 Disease severity is classified using the Hurley clinical staging system (Table 1; Figure 1).5,8,9

Table 1. Hurley Classifications of Hidradenitis Suppurativa5,8

Hurley StageDescription
ITransient inflammatory lesions and abscess formation without sinus tracts or scarring
IISeparate lesions with recurrent abscesses and tunnel formation/sinus tracts. Mild scarring can appear.
IIIDiffuse involvement with multiple interconnected sinus tracts and abscesses with scarring
Figure 1. Images of Hurley Stage 1 (A), Stage II (B), and Stage III (C) hidradenitis suppurativa. Source: Scala et al.9

The diagnosis of HS can be made solely based upon clinical observation of location and morphology of skin lesions; biopsy is rarely required.2,10 Bacterial cultures may be obtained if there is concern for secondary bacterial infection or to differentiate HS from infectious entities. However, they are not routinely recommended for every patient.3

There are 3 major criteria required for a clinical diagnosis of HS.10 The first is that the lesions are painful nodules that intermittently form abscesses that can rupture, leaking a purulent and malodorous discharge.7,11 Secondly, the lesions are localized to the typical intertriginous regions often in a symmetrical pattern.11 Lastly, the condition is chronic with recurrent flares or there is a family history of HS.7,11 Chronicity has been referred to as the hallmark feature of HS and differentiates it from other possible diagnoses such as boils or furunculosis.2

Conventional Treatment Options

Topical clindamycin is often used as initial therapy for mild localized disease; for refractory or widespread HS, oral antibiotics are considered next.7,12,13 Oral tetracyclines are used to decrease the skin bacterial load and for the associated anti-inflammatory effects.7,12,13 Tetracycline 500 mg twice a day is a recommended regimen for mild to moderate disease over a 4-month treatment course or as maintenance therapy.7,12 Antiandrogenic medications such as oral contraceptive agents, spironolactone, and metformin may be used based on individual patient cases.12,13

Patients with mild to moderate disease burden refractory to treatments previously mentioned may benefit from systemic treatment such as rifampin and clindamycin combination therapy, acitretin, or dapsone.12,13 Laser therapy with neodymium-doped yttrium aluminum garnet (Nd:YAG) laser has been used with this patient population.13

Patients with moderate to severe refractory HS are candidates for biologic therapy, such as adalimumab (the only FDA-approved treatment for HS) and infliximab, oral retinoids, or wide local excision.12,13 Acute symptomatic lesions can be treated with warm compresses and intralesional corticosteroid injections, but incision and drainage are not routinely recommended.7,13

Lifestyle Modifications

Although effective interventions exist to improve symptoms and control the disease burden of HS, no cure exists.7 The absence of a cure and the relapsing nature of HS make it a challenging disorder to manage.12 Management involves a multimodal approach such as a combination of pharmacologic and nonpharmacologic therapy including outpatient procedures and surgeries.7 Hidradenitis suppurativa can be managed by primary care providers, but refractory HS in Hurley Stage II or III warrants referral to a dermatologist.7

General nonpharmacological recommendations should also be used for all patients with HS regardless of staging or disease severity.7,14 These recommendations include lifestyle modifications such as weight loss, avoidance of foods with high glycemic index, smoking cessation, avoidance of irritating personal care products, and use of loose, absorbent clothing.7