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 and under the breasts. It is also known as ‘acne inversa’.

Hidradenitis suppurativa

What causes hidradenitis suppurativa and who gets it?

The exact cause of hidradenitis suppurativa remains unclear. What is understood is that the condition is a disorder of follicular occlusion. This begins with follicular plugging that obstructs the apocrine gland ducts and perifolliculitis around the ducts. This is followed by rupture of the follicular epithelium, bacterial infection and formation of sinus tracts between abscesses under the skin, all which lead to the characteristic symptoms and signs of hidradenitis suppurativa.

The following are thought to play a role in the development of hidradenitis suppurativa.

• Genetics – frequently reported cases of hidradenitis suppurativa affecting multiple members of a family
• Sex hormones – apocrine sweat glands are stimulated by androgen and suppressed by oestrogen (exact role these hormones play remains controversial)
• Endocrine factors – obesity, polycystic ovaries, hirsutism, acne are common findings among women with hidradenitis suppurativa
• Cigarette smoking – hidradenitis suppurativa occurs more frequently in smokers than non-smokers

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.

What are the signs and symptoms of hidradenitis suppurativa?

The extent and severity of the disorder varies widely between individuals. Initially a firm pea-sized nodule (0.5-1.5 cm diameter) resembling acne may appear on one site. These lesions may resolve spontaneously or within hours to days rupture and ooze a pus-like discharge. These may heal without treatment but at a later time new lesions recur in the adjacent area. If uncontrolled, this leads to development of larger lesions (golf ball size), sinus tract formation, and involvement of multiple sites. Three distinct clinical stages have been defined for the condition.

• 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.

Disease may spread to involve less commonly associated sites including the nape of the neck, waistband and inner thighs. Anogenital involvement most commonly affects the groin, mons pubis, vulva, sides of the scrotum, perineum, buttocks and perianal folds. The abscesses and sinus tracts can be painful.

What is the treatment of 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 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 infection. Flucloxacillin or dicloxacillin are the most suitable, except in the case of penicillin allergy.
• 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.
• 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 suppurativa. Acitretin is unsuitable for females of childbearing potential, but may be more effective than isotretinoin and long term remissions have been reported.
• Metformin, usually used in type 2 diabetes, may be beneficial.
• 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.
• 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.
• Nodules and abcesses may be de-roofed and scraped out.
• Persistent hidradenitis lumps may be excised after several months of conservative treatment (i.e. waiting and/or antibiotics).
• Radical excisional surgery is reserved for very severe cases of hidradenitis suppurativa.
• Experimentally, laser hair removal and surface tissue ablation may be useful in some patients.
• Photodynamic therapy using methyl aminolevulinate has been used but does not appear to be very effective.