Axillary pain and swelling

A 44 year old man with a body mass index of 41 kg/m² presented to the surgical outpatient clinic with a three month history of swelling, erythema, and small tender lumps in his right axillary region (fig 1). His general practitioner had prescribed oral antibiotics (three courses) and although the symptoms subsided temporarily, the condition soon recurred. He had had this problem on and off for the past 20 years (recurrent abscesses, pain, discharge, and occasional bleeding) and had had three surgical interventions (incision and drainage procedures), but with limited success. The patient had similar problems in the left axilla (fig 2) and both groins. He was a former smoker and his medical history was unremarkable apart from acne, varicose veins, and depression.

Questions

1. What is this condition?
2. Briefly describe its aetiology and pathophysiology.
3. What are the differential diagnoses?
4. What are the management options?

Answers

1. Hidradenitis suppurativa.
2. It is caused by recurrent infections of the apocrine sweat glands. Although the exact cause of this condition is unclear, it is widely believed that occlusion of the apocrine or follicular duct by keratinous plugging serves as the initiating event, leading to ductal dilatation and stasis of secretions in the glandular component. Bacteria may enter the apocrine system through hair follicles, become trapped, and then multiply in the nutrient environment of the apocrine sweat glands. The glands subsequently rupture, leading to extension of infection and further local inflammation, tissue destruction, and skin damage.
3. Other cutaneous infections such as furuncles, carbuncles, sebaceous cysts, lymphogranuloma venereum, epidermoid or lymphoid cysts, erysipelas, and cutaneous tuberculosis. If the problem occurs in the perineal or perianal region, conditions such as Crohn’s disease, perianal abscess, and anal fistula should be considered in the differential diagnosis.
4. Simple abscesses (in the initial stages) may respond to oral antibiotics. Once the abscess becomes established, an incision and drainage is usually required. Recurrences can lead to sinus tracts, skin tags, and contractures. In such instances, surgical excision of all hair bearing areas (including the apocrine sweat glands) in the affected region is the standard procedure. Coverage of the excised area is achieved by leaving the wound to granulate (to heal by secondary intention), closing the wound primarily (suturing the wound immediately after the affected area is excised), skin grafting, or the use of local tissue flaps (simple reconstructive surgery).

Fig 1 Right axilla (top); Fig 2 Left axilla

Discussion

Hidradenitis suppurativa, also called acne inversa, is a debilitating chronic suppurative disease of the apocrine sweat glands which occurs mainly in regions such as the axilla, groin, and perineum. It is manifested by recurrent abscesses, fistulas, and scarring.^w1 It is thought to affect roughly one in 300 adults.^w2 It occurs in both sexes, but seems to be more common in females (although perianal disease may be twice as common in males). The age of onset varies from adolescence to early or mid-adult life. Several factors such as obesity, smoking, use of the contraceptive pill, stage of the menstrual cycle (latter half), and pregnancy are thought to predispose to hidradenitis suppurativa.^w3 A familial predisposition with an autosomal dominant pattern of inheritance has also been suggested.^w4

Hidradenitis suppurativa starts with deep seated nodules, which tend to coalesce and may become infected, resulting in an acute abscess.^w5 At this stage, patients pre-sent with pain, swelling, and redness in the affected region. If the abscess is left untreated it usually bursts, releasing a purulent, malodorous discharge. Sweating, heat, stress, tight clothing, and friction all exacerbate the condition. This may explain why it worsens during summer.^w6

Diagnosis is based on clinical findings, and no investigation is needed in the acute stages of the disease.^w7 Treatment with empirical oral antibiotics (an anti-staphylococcal and anti-streptococcal for axillary abscess, with an anti-anaerobic for perianal involvement) may result in resolution of the acute symptoms. Warm baths, hydrotherapy, and topical cleansing agents to maintain hygiene and reduce bacterial load are recommended to complement the antibiotic treatment. Topical antibiotics are of limited value. Although hormone treatment to reduce androgen levels (for example, cyproterone acetate (antiandrogen) and leuprolide (synthetic gonadotrophin releasing hormone)) have been tried, they are not used routinely. If the abscess does not resolve with conservative treatment (usually after 48 hours), incision and drainage may be indicated.^w2 The collection (pus) is sent for culture and sensitivity, and antibiotic treatment can then be determined based on culture results.

In cases of recurrence (leading to sinus tracts, chronic pain, scarring, and contractures) wide radical resection of all skin with apocrine glands is strongly recommended. Radical excision minimises the recurrence rate, as opposed to limited surgical interventions such as incisions, drainage procedures, or partial excision. Some commonly advocated methods to heal the excised area include leaving the wound to granulate, skin grafting, or the use of local tissue flaps. Primary closure is not recommended.^w5

If inadequately treated in the initial stages, hidradenitis suppurativa often progresses to a chronic state, resulting in persistent pain, purulent discharge, sepsis, sinus tract and fistula formation, and dermal scarring. In addition, there is progressive destruction of normal skin architecture with the development of periductal and periglandular inflammation and dermal and subcutaneous fibrosis. Other complications of chronic hidradenitis suppurativa include anaemia, interstitial keratitis, osteomyelitis, fistulous communications to pelvic organs, and malignant transformation (to squamous cell carcinoma).^w8

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3. Fitzsimmons JS, Fitzsimmons EM, Gilbert G. Familial hidradenitis suppurativa: evidence in favour of single gene transmission. J Med Genet 1984;21:281-5.
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7. Bocchini SF, Habr-Gama A, Kiss DR, Imperiale AR, Araujo SEA. Gluteal and perianal hidradenitis suppurativa; surgical treatment by wide excision. Dis Colon Rectum 2003;46:944-9.
8. Ritz JP, Runkel N, Haier J, Buhr HJ. Extent of surgery and recurrence rate of hidradenitis suppurativa. Int J Colorect Dis 1998;13:164-8.