Hidradenitis Suppurativa

Hidradenitis Suppurativa or HS is a common inflammatory skin condition involving the development of painful spots and abscesses mainly in the armpits, groin and underneath the breasts

 

What is this skin condition?

Hidradenitis Suppurativa or HS is a common inflammatory skin condition involving the development of painful spots and abscesses mainly in the armpits, groin and underneath the breasts. It can occur on the abdomen and thighs particularly in patients who are over weight. Involvement of the buttocks is also sometimes seen, most commonly in male smokers. The skin lesions are often painful and in severe cases can become persistent and leak pus.

Why have I got it?

The precise cause of HS is not known. As with most diseases there are likely to be genetic and environmental causes. The disease is focussed in areas of the body where there are naturally more bacteria. The disease process involves structures in the skin where bacteria can accumulate such as apocrine sweat glands and hair follicles. There are probably 2 things that need to happen to develop HS:-

  1. Skin structures in affected areas become blocked. This leads to bacterial overgrowth
  2. Patients who have an over sensitive skin immunity respond to the excess bacteria with inflammation leading to the clinical appearance of HS.

HS is far more common in people who are overweight or who smoke, with 90% of HS sufferers being either overweight or smokers. If you are overweight your flexural areas (armpits, groin) are less exposed to the air and are warmer leading to a greater chance for bacterial overgrowth. Smoking is thought to lead to blockages in skin structures as the cancer forming chemicals affect the way the skin cells grow.  However , most people who are overweight or smoke do not get HS and some normal weight non-smokers get HS.

This can be explained by a 2 hit hypothesis involving (1) bacterial overgrowth and (2) an  oversensitive immune system.

For HS to occur you need both things to happen. Some people are born with a tendency to skin structure blockages (there are some links to a gene which makes a protein that helps to keep skin structures open), others are born with an oversensitive skin immunity and some are born with both. If you have both risk factors you will get HS even if you are thin and do not smoke. If you only have the oversensitive skin immunity you will be okay as long as you do not trigger your immune system. However, if you smoke or become overweight and develop blockages of your sweat glands or hair follicles, leading to increased bacterial growth, you will trigger your sensitive skin immunity and go on to get the inflamed spots and abscesses of HS.

We should emphasize that the above explanation remains a hypothesis. The precise cause of HS is likely to be complex. Clinical experience shows us that there are definitely different types of HS and the cause is likely to differ between individuals.

These images show axillary HS at different stages of inflammation. Image 1 shows HS with scarring but minimal inflammation whereas image 2 shows more inflammation with early hypertrophic scar formation.

Image 1

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Image 2

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Comparing the treatment options:

Treatment of HS has 3 main strategies

  1. Reduce the bacterial load . This should then minimise the immune response and reduce the inflammation
  2. Reduce the blockages. Various retinoid type drugs have been used to try and do this with limited success.
  3. Reduce the excessive inflammation by using medicines to suppress the immune system.

Self-treatment

If you are over-weight you must try and lose weight. If you smoke, you must stop smoking. Successful treatment of HS is hard and you need to do everything you can to reduce the tendency for HS lesions to appear. There are of course thin, non smokers with HS and so it is not guaranteed that correcting these issues will help. However, the association between HS and smoking and excess weight is significant and cannot be ignored.

Washing with an antibacterial product such as hibiscrub may be helpful. This can be purchased from the chemist or from amazon via this link.

Help from your GP

  1. Antibiotic lotions can be useful.  Zineryt is an erythromycin and zinc based lotion. Dalalcin T contains clindamycin. These solutions are applied to the affected areas twice per day.
  2. Systemic antibiotics may be helpful. Commonly used antibiotics include tetracyclines such as oxytetracycline , doxycycline and lymecycline. Erythromycin is also used. They should be taken for 3 months. It may be useful to take photos before and after to help judge whether treatment has been successful.

 

Help from a Dermatologist

  1. More complex combinations of oral antibiotic such as rifampicin plus clindamycin taken for 3 months can be helpful. Liver function must be monitored.
  2. Intravenous antibiotics such as ceftriaxone can have a big impact. They are often administered at a day unit or an out-patient iv antibiotic clinic.
  3. Retinoid drugs such as isotretinoin or acitretin. These medications normalise the growth of skin cells called keratinocytes which are involved in the blockage of sweat glands and hair follicles. Isotretinoin is normally used for acne and acitretin is normally used for treating psoriasis. Both of these drugs have been used to treat HS with isolated reports of benefit but the evidence that they are effective more generally is poor.
  4. Immunosuppressive treatments. There is now good evidence that the skin immune system is overactive in HS. Recent large scale clinical trials have shown that the medication, adalimumab is effective in reducing the inflammation in HS. Adalimumab is a manufactured antibody which blocks an inflammatory protein called TNF alpha. It is not effective in all patients and there are some possible side effects including skin and lung infection. The brand name for adalimumab is Humira.
  5. Other immunosuppressive medications such as infliximab and ciclosporin have also been used although these medications have not been studied in as much detail as adalimumab and are not licensed for the treatment of HS.

 

Help from a plastic Surgeon

In severe cases of HS the chronic inflammation leads to fixed abscesses which connect to the skin surface by channels called fistulas. Once these become established, bacteria grow within them and the action of the immune system on the bacteria produces pus which is discharged. These structural changes do not respond to medical treatment and sometimes surgery is needed. To be effective large areas of abnormal skin will sometimes need to be removed. This can lead to significant scarring but patients are often very grateful to be relived of the pain and discharge. In larger hospitals severe HS is increasingly managed by teams of Dermatologists and plastic Surgeons working together.

 

 

Other sources of information:

The British Association of Dermatologists have an information leaflet.

Dermnet NZ have an information page on their website.

 

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