SYNONYMS : Hidradenitis Axillaris, Abscess of the Apocrine Sweat Glands, Acne Inversa, Apocrinitis.
DEFINITION : Hidradenitis Suppurativa is a chronic suppurative (producing pus) disease of the Apocrine Sweat Glands of the skin and subcutaneous region. It is characterized by the development of firm, tender and painful red nodules followed by the formation of fluctuant abscesses containing pus and discharging sinuses and fistulae under the skin with scar formation, primarily within the folded areas of skin that contain apocrine glands i.e. axillae and groins.
A Sinus is a passage leading to a cavity containing pus. A Fistula is an abnormal track of a few to several centimetres long under the skin with two or more openings on the surface of the skin.
MECHANISM, SYMPTOMS AND SIGNS : Apocrine Sweat Glands lie deep in the dermis and are normally found in relation to the hair of the axillae (armpits), groins, inguinoscrotal groove, pubis, peri-anal regions, perineum and inguinovulval groove. Less common, “ectopic” sites are on the anterior chest wall, peri-areolar and peri-umbilical regions and natal cleft. Also, in the sternal area in males and the sub-mammary regions in females. Uncommon sites which could be extensive are the back of the neck and buttocks. It is a post pubertal process. In females, the armpits are mostly affected from puberty to menopause and in males, the groins and peri-anal area are mostly affected from puberty to middle age, especially in obese patients in both genders.
The initiating event is unknown. The mechanism of the development of the lesions is when apocrine sweat glands become obstructed by a plug of an abnormally formed keratin causing the gland to swell and rupture which is followed by inflammation, invasion and infection by anaerobic organisms (bacteria growing and living in the absence of oxygen) and also by gram positive and negative bacteria such as staphylococcus aureus, streptococcus pyogenes, E. coli, Proteus Vulgaris and Pseudomonas aeruginosa. This is followed by the formation of abscesses, sinuses and fistulae tracks of a few to several centimetres in length which borrows deep under the skin with openings on the surface which discharges an unpleasant and disabling smell.
When a probe is used to explore the burrowing sinuses, the latter may extend for several centimetres running horizontally deep under the skin surface. The natural history of the disease varies considerably, from mild, recurrent, red, tender and limited nodules, up to severe, progressive, widespread, painful nodules and chronic discharging sinuses with considerable scarring and thickening of the skin which restricts mobility with soiling of clothes and unpleasant smelling discharge and anything in between.
P.S. Keratin is an insoluble substance that normally occurs in the outer layer of the skin, nails, hair, hooves of animals etc. The cause of keratin plug blockage is unknown. However, the blockage is not related to underarm shaving, the use of deodorants or the bad practice of applying body powders to armpits, groins and perineum.
DIAGNOSIS : The diagnosis is from the history and clinical examination. There is no specific diagnostic investigation or test.
DIFFERENTIAL DIAGNOSIS : The clinical findings in Hidradenitis Suppurativa must be differentiated from cystic acne and can be extremely difficult including the ones that occur on the back of the neck. Also, from ordinary abscesses, carbuncle, common furuncles, Bartholin abscess, Pilonidal Sinuses, actinomycosis, lymphogranuloma venereum of the peri-anal area and other forms of sinuses and fistulae. The perianal may be confused with Crohn’s disease, mucoid carcinoma and simple perianal fistulae.
TREATMENT is either expectant or surgical operations.
EXPECTANT TREATMENT is usually carried-out by a dermatologist and it is rewarding in the early stages but it has its limitations. Generally, the patient should avoid excessive sweating and should use loose-fitting light and absorbent 100% cotton clothing. Also, the use of topical Aluminium Chloride to the involved areas to reduce sweating. The combination of intralesional glucocorticoids, oral antibiotics, isotretinoin, cleocin, infliximab, finasteride etc. are useful. In severe cases, there is anaemia and hypoprotinemia and should be corrected.
IN YOUNG MARRIED FEMALES, it is very important to exclude pregnancy prior to the use of these medications.
SURGICAL TREATMENT : Surgical operation on Hidradenitis Suppurativa is a matter of clinical judgement. It is a protracted disease and its course is unpredictable and cure cannot be guaranteed. It depends on the age of the patient, grade, severity, site and area size of the disease. For example, the process of subcutaneous nodules developing into abscesses is very painful especially during movement if it is in the axillary and groin areas or when sitting if it is in the gluteal area or an abscess in the scrotum.
In such cases, the disease seriously impairs the patient’s quality of life and their day to day activities. In such cases, surgical operation is strongly indicated. The patient should be warned that surgery may be followed by the development of a new lesion(s) at another site. Furthermore, the patient should be aware that the disease is unlikely to settle spontaneously until middle age.
By and large, surgical treatment falls into six categories:
1) Total excision of the involved skin, for example the axillary skin. Approximation of the edges of the wound using interrupted non-absorbable fine Monofilament Nylon.
2) Discharging sinuses and fistulae usually are deeper than the dermis i.e. subcutaneous (under the skin). With the aid of Lockhart Mummery fistula director, the tissues of the track are all sharply divided and laid open by cutting on the groove in the fistula director with no. 11 Swan Morton blade, curreting septic granulation and careful excision of the roof. The remaining wound is left exteriorized and to heal by granulation and epithelialization (second intention), using none adhering dressings such as Adaptic sheets which needs to be change whenever necessary.
Second Intention is a process of healing, cure and restoration of integrity of the tissue where the wound closure takes place from the base and both sides of the remaining cavity towards the surface.
3) An abscess needs incision and evacuation of the contents.
4) Total excision of the involved skin. The remaining wound shall be left to heal by second intention.
5) Total and wide excision followed by skin graft is the procedure of choice in severe cases. Such operations are carried out in centres specialized in this type of operation where it needs special facilities, skill and expertise of the staff including the surgeon. The patient needs hospitalization for a few weeks.
6) In severe and extensive involvement of the perineum and peri-anal area, a temporary surgical de-functioning colostomy followed, a few weeks later, by elective excision and skin grafting. Such procedures are carried out in the above mentioned specialized centres.
In any type of the above surgical procedure, the patient should be warned that successful surgery may be followed by the development of a new disease at another site.
I would like to emphasize the following:
1) The disease will improve sometime during middle age or menopause.
2) These patients are anxious and depressed because of the chronicity of the disease, soiling of clothing, pain, discharge of pus and unpleasant smell. They need reassurance and may need anti-depressants and anxiolytic medication.