What is hidradenitis suppurativa?
Hidradenitis suppurativa is an inflammatory skin disease that is characterised by recurrent boil-like lumps (abscesses) that culminate in pus-like discharge, difficult-to-heal open wounds and scarring. It commonly occurs on apocrine sweat gland-bearing skin such as in the groin, the underarms (axillae) and under the breasts.
It is also known as ‘acne inversa’ (inverse acne). This is probably a better name for the condition, as the term "hidradenitis" implies it starts as an inflammatory disorder of sweat glands, which is now known to be incorrect.
What causes hidradenitis suppurativa and who gets it?
The exact cause of hidradenitis suppurativa remains unclear. The condition is a disorder of follicular occlusion. This begins with follicular plugging that obstructs the apocrine gland ducts and leads to perifolliculitis (inflammation around the ducts). This is followed by rupture of the follicular epithelium, bacterial infection and formation of sinus tracts between abscesses under the skin, ie the characteristic symptoms and signs of hidradenitis suppurativa.
The following are thought to play a role in the development of hidradenitis suppurativa.
- Genetics – hidradenitis suppurativa may affect multiple members of a family
- Sex hormones – apocrine sweat glands are stimulated by androgen and suppressed by oestrogen (the exact role of these hormones remains controversial)
- Endocrine factors – obesity, polycystic ovaries, hirsutism, acne are common findings among women with hidradenitis suppurativa
- Pro-inflammatory cytokines (messenger proteins) that drive inflammation
- Cigarette smoking – hidradenitis suppurativa occurs more frequently in smokers than non-smokers
- Secondary bacterial infection
Women are affected by hidradenitis suppurativa three times as often as men; the reason for this is unknown. The condition most commonly occurs between 20–40 years and coincides with the post-pubertal increase in androgen levels. Disease onset rarely occurs before puberty and after menopause.
In some people, hidradenitis suppurativa makes up one part of follicular occlusion syndrome, when it is associated with acne conglobata, dissecting cellulitis and pilonidal sinus. Hidradenitis suppurativa is also associated with Crohn disease.
What are the signs and symptoms of hidradenitis suppurativa?
The extent and severity of hidradenitis suppurativa varies widely between individuals. Initially, a firm pea-sized papule or nodule (0.5–1.5 cm diameter) may appear on one site, eg the armppit or groin. It may resemble an acne pimple. These lesions may resolve spontaneously, or, within hours to days, they may rupture and ooze a pus-like discharge. The nodules may heal without treatment. At a later time new lesions recur in the adjacent area and may include larger nodules, pseudocysts and abscesses, sinus tract formation, and involvement of multiple sites.
Hidradenitis suppurativa may spread to involve both armpits, on and under the breasts, the nape of the neck, waistband and inner thighs. Anogenital involvement most commonly affects the groin, mons pubis, vulva (in females), sides of the scrotum (in males), perineum, buttocks and perianal folds. The abscesses and sinus tracts can be painful.
How is severity and extent of hidradenitis assessed?
Severity and extent of a disease should be recorded at assessment and when determining the impact of a treatment. Photography of affected areas can also aid follow-up. Two scoring systems are in common use: Hurley Stages and Sartorius Hidradenitis Suppurativa Score.
The Hurley system describes three distinct clinical stages.
- Stage 1 – solitary or multiple, isolated abscess formation without scarring or sinus tracts
- Stage 2 – recurrent abscesses, single or multiple widely separated lesions, with sinus tract formation
- Stage 3 – diffuse or broad involvement, with multiple interconnected sinus tracts and abscesses.
Sartorius Hidradenitis Suppurativa Score
The Sartorius Hidradenitis Suppurativa Score is made by counting involved regions, nodules and sinus tracts.
- Anatomic region involved (axilla, groin, genital, gluteal, or other inflammatory region left and/or right): 3 points per region involved
- Number and scores of lesions (abscesses, nodules, fistulas, scars): 2 points for each nodule, 4 points for each fistula, 1 point for each scar, 1 point each for "other"
- Longest distance between 2 relevant lesions (ie, nodules and fistulas, in each region, or size if only 1 lesion): Less than 5 cm, 2 points; less than 10 cm, 4 points; more than 10 cm, 8 points
- Lesions clearly separated by normal skin in each region: If yes, 0 points; if no, 6 points
In hidradenitis suppurativa, it is also useful to consider the degree of pain, the number of flares, and the impact on daily life (e.g. using Cardiff Dermatology Life Quality Index or DLQI questionnaire).
What factors are associated with severe disease?
Severe hidradenitis (Hurley Stage 3) has been associated with:
- Male gender
- Axillary and perianal involvement
- Disease duration
What is the treatment for hidradenitis suppurativa?
Medical management of hidradenitis suppurativa is difficult. The aim is to catch the disease in its early stages and treat and control these milder forms. Antibiotics are usual therapy (partly to eradicate secondary bacterial infection and partly for their anti-inflammatory action) and long courses may be necessary. Weight loss in obese patients and smoking cessation are recommended.
General measures include:
- Don't smoke. This is very important. Stopping smoking can lead to improvement within several months.
- Follow a low-glycaemic, low-dairy diet, and aim for ideal body weight.
- Wash with antiseptics or acne preparations to reduce skin carriage of commensal bacteria. Hydrogen peroxide solution and medical grade honey have been found helpful.
- Wear loose fitting clothing to avoid friction.
Medical management includes:
- Topical anti-acne antibiotics such as clindamycin or erythromycin applied to affected areas in combination with benzoyl peroxide
- Short course of oral antibiotics for acute abscesses (red, hot painful discharging lump) due to staphylococcal infectionFlucloxacillin or dicloxacillin are the most suitable, except in the case of penicillin allergy. Which antibiotic is used may depend on bacteriological cultures and antibiograms
- Prolonged courses of tetracycline or metronidazole (minimum 3 months), fluoroquinolones and dapsone are used to reduce colonisation by coagulase-negative staphylococci and anaerobes and also for their anti-inflammatory action
- Three-month courses of the combination of clindamycin and rifampicin may be the most effective medical treatment in severe cases.
- Metformin, usually used in type 2 diabetes, is also beneficial when taken longterm, often reducing the number and severity of inflamed nodules
- Trial of oral contraceptive pill for 12 months or more. Those containing the antiandrogenic progesterones drospirenone or cyproterone acetate are often more effective than standard combined pills. The antiandrogenic diuretic spironolactone may also be of benefit and finasteride has been reported to help some patients
- Oral retinoids (vitamin A derivatives) for 6 to 12 months, especially isotretinoin, which are very effective for acne, may also help hidradenitis suppurativaAcitretin is unsuitable for females of childbearing potential, but may be more effective than isotretinoin and long term remissions have been reported
- Colchicine has been reported to help some patients with hidradenitis suppurativa
- Systemic corticosteroids or intralesional corticosteroids (injections directly into the nodules) may reduce severe inflammatory lesions
- Other immunomodulatory treatments, including ciclosporin, methotrexate and azathioprine, have been successful in some patients with severe disease
- In severe cases, the use of biological response mediators such as infliximab, adalimumab, etanercept and other TNFα antagonists, may be worth considering. These are not funded by PHARMAC for hidradenitis in New Zealand
Surgical management includes:
- Incision and drainage of abscesses – at the very painful pointing stage
- Scraping out nodules and abcesses
- Excision of persistent hidradenitis lumps
- Radical excisional surgery
- Laser hair removal and surface tissue ablation
- van der Zee HH, Boer J, Prens EP, Jemec GB. The effect of combined treatment with oral clindamycin and oral rifampicin in patients with hidradenitis suppurativa. Dermatology. 2009;219(2):143-7. Epub 2009 Jul 8.
- Slade DEM, Powell BW, Mortimer PS. Hidradenitis suppurativa: pathogenesis and management. The British Association of Plastic Surgeons 2003; 56: 451-461
- Book: Textbook of Dermatology. Ed Rook A, Wilkinson DS, Ebling FJB, Champion RH, Burton JL. Fourth edition. Blackwell Scientific Publications.
- Buimer MG, Wobbes T, Klinkenbijl THG. Hidradenitis suppurativa British Journal of Surgery 2009:96;350-360
- Schrader AM, Deckers IE, van der Zee HH, Boer J, Prens EP. Hidradenitis suppurativa: a retrospective study of 846 Dutch patients to identify factors associated with disease severity. J Am Acad Dermatol. 2014 Sep;71(3):460-7.
On DermNet NZ:
- Hidradenitis suppurativa (German version, January 2010)
- Sebaceous adenitis
- Follicular occlusion syndrome
- Hidradenitis suppurativa US National Library of Medicine Genetics Home Reference
- Hidradenitis Suppurativa – Medline Plus
- The Hidradenitis Suppurativa Trust
- HS-USA Support Group
- Hidradenitis Suppurativa Foundation, Inc.
- Dermatologic Manifestations of Hidradenitis Suppurativa – Medscape Reference
- Hidradenitis Suppurativa – British Association of Dermatologists
- Patient information: Hidradenitis suppurativa (The Basics) – UpToDate (for subscribers)