Hidradenitis suppurativa

What it is

Hidradenitis suppurativa, or HS, is a chronic, recurrent and painful condition in which the skin becomes inflamed — red, tender and swollen — in areas that contain apocrine sweat glands, found mainly in the armpits, breasts and groins. Within HS lesions the hair follicles are blocked, which causes a mixture of boil-like bumps, areas leaking pus, and scarring.

HS tends to begin after puberty and is more common in women between the ages of 20 and 35. It is estimated to affect about one per cent of the population. As well as the armpits, groins and area below the breasts, it can affect the genitals, the pubic region and the area around the anus. It appears as multiple painful lumps which can merge and form abscesses, and which discharge pus that may smell. When it keeps recurring it can lead to cysts, scars, sinus tracts and fistulas, restrict movement of the arms, and block the lymph channels so that arms, legs or genitals swell.

What causes it

It is still not clear why some people get this disease. The inflamed spots are thought to develop when the hair follicles become blocked. Hormones may play a part, and in women HS may be worse before a period. Bacteria that normally live on the skin may get trapped in the blocked gland, and the immune system produces the inflammation. Smoking and obesity are both linked with HS, and it sometimes runs in families.

How we treat it

Treatment is tailored for each individual. General measures include reducing weight, wearing loose clothing, avoiding smoking, and cleansing the affected areas with antiseptics.

Your dermatologist may prescribe courses of antibiotics to control secondary infection, and topical antibacterial agents may help. In some cases a drug called isotretinoin is prescribed, and in severe cases a biological agent called adalimumab often helps. Wounds may need dressings. Surgery may be needed to drain pus or remove sinus tracts.

HS usually persists for many years, but it can eventually become inactive, and treatment can give remissions for long periods of time. In women its severity often reduces around the menopause.