Hidradenitis suppurativa (HS)
refers to a chronic, suppurative, cutaneous process that results from
occlusion of follicles and secondary inflammation of apocrine glands.
Recurrent lesions develop in the axillae, groin, vulva, and perineal or
perianal areas. Chronic infection and draining abscesses lead to
scarring of the affected sites. The incidence is as high as 1 in 300, with
no racial predilection.
The name hidradenitis suppurativa is a misnomer, and there have been proposals to abandon it in favor of the more accurate term acne inversa. Unlike acne vulgaris, acne inversa is localized to nonfacial regions, sebum excretion is not increased, and affected areas tend to be rich in apocrine glands that are engulfed in, but not the original source of, the inflammatory process
PATHOGENESIS The most likely mechanism responsible for the development of HS is occlusion of the hair follicle (rather than the apocrine gland) due to a defect in terminal follicular epithelium . Support for this theory is illustrated by the following observations:
histopathology of axillary skin excised from 12 patients with HS revealed
that ruptured cysts had a lining of stratified squamous epithelium similar
to the epidermis and the epithelium lining hair follicles; there was no
gross dilatation of the apocrine glands
A review of skin biopsies from 101 HS (acne inversa) patients reported follicular occlusion in all specimens, regardless of disease duration
A study of 51 specimens from 11 patients with HS (acne inversa) noted poral occlusion, sinus tracts, or cysts; no primary apocrine involvement was observed. The authors suggest that the homogeneous histopathology of acne inversa supports its classification as a follicular disease.
A prospective examination of 27 consecutive patients (39 biopsies) found that the initial lesion was an occluding spongiform infundibulofolliculitis; stasis and destruction of apocrine glands was a secondary phenomenon. Similar findings were noted in another study in which follicular occlusion by keratinous material was a primary event, with subsequent active folliculitis and secondary destruction of the skin adnexae and subcutis.
HS is associated with other conditions in which follicular occlusion is a prominent feature: acne conglobata; pilonidal sinus; and dissecting cellulitis of the scalp.
After the plugging occurs, bacteria invade the apocrine system via the hair follicles, become trapped beneath the keratinous plugs, and multiply rapidly in the nourishing environment of apocrine sweat. The glands subsequently rupture and spread the infection to adjacent apocrine and eccrine glands, further extending the tissue destruction and skin damage.
The significance of bacterial infection in HS is controversial. Although bacterial superinfection with streptococci, staphylococci, and coliforms are considered part of the pathogenesis of the disorder, cultures from lesions are frequently sterile and antibiotics are not curative.
Hyperandrogenism has been suggested as a causal factor in womem based upon the following observations:
A higher free androgen index (due to low serum sex hormone-binding globulin [SHBG] concentrations) and total serum testosterone concentration in patients than in normal controls
Premenstrual flares have been associated with the androgenic properties of progesterone and the surge of other ovarian androgens are common.
HS is more prevalent in hirsute women than in weight-matched controls and, in case reports, has improved after therapy that reduced ovarian and adrenal androgen production
However, the association between androgens and HS remains controversial and may be due, in part, to obesity as many patients with HS are obese and SHBG is negatively correlated with body mass index A report on the endocrine status of 66 women with HS found no evidence of biochemical hyperandrogenism when compared to age-, weight- and hirsute-matched controls Similar findings were noted in another study. Also arguing against a role for androgens in HS are the observations that, although acne is more prevalent and severe in males, HS is predominantly a female disease (13:5), and that HS has been treated effectively with testosterone in selected patients
HS has been associated with other endocrine disorders, such as diabetes, Cushing's disease, and acromegaly
Genetic There appears to be a familial predisposition to HS. In one report, a positive family history of HS was present more often in patients than controls matched for age and sex (26 versus 2 percent). Other studies examined 62 affected persons (40 females and 22 males) in 11 families. The authors suggested that HS has a genetic etiology in a pattern consistent with autosomal dominant inheritance.
Other HS has been associated with several cutaneous abnormalities, behaviors, and nonprescription drugs However, causality has not been proven.
epithelium-lined structures containing hair shafts
Unlike acne, significant sebaceous gland involvement is not a component of HS either by histologic examination or by measuring the sebum excretion rate
Pathologic examination of excised early lesions demonstrate a local cellmediated immune reaction with T-cell lymphocyte predominance. In one series, the early lesions were associated with a sharp decline in the T-helper/suppressor ratio in the plasma. However, immunologic studies in patients with HS have shown mixed results. As an example, systemic cell mediated immunity and neutrophil function were normal in one report, while a marked reduction in T-lymphocyte counts was found in another.
Women have mostly axillary and vulvar disease, while men are prone to perianal involvement. Single or multiple cutaneous sites can be affected. The disease may be mild and limited or severe, with new lesions continually developing and causing chronic, widespread, deep infection (show figure 1 and show figure 2).
Recurrent deep boils for more than six months in flexural sites
Onset after puberty
Poor response to conventional antibiotics
Strong tendency toward relapse and recurrence
Comedones in apocrine, gland-bearing skin
No pathogens from routine cultures of pus from boils
Personal or family history of acne or pilonidal sinuses
Exacerbation of boils premenstrually in women
Late disease is characterized by chronic infection, draining abscesses, nodules, and scarring. The diagnosis is based upon characteristic clinical manifestations, biopsy is neither required nor diagnostic. Cure is unlikely with severe disease extensively involving a skin site
Follicular pyodermas (eg, folliculitis, furuncles, carbuncles, pilonidal cysts) are also infections arising from a hair follicle. However, they do not result in the widespread scarring, pitting, and induration observed with HS.
Granuloma inguinale causes ulcerations on the vulva or perianal areas, but unlike HS, may involve the vagina and cervix. Untreated, secondary infection leading to scarring and tissue destruction can occur. This diagnosis is established by demonstrating Donovan bodies in scrapings or tissue smears from the ulcers. Histology shows acanthosis with elongation of the rete pegs and micro-abscesses.
Perianal and vulvar manifestations of Crohn's disease include abscesses, rectoperineal and rectovaginal fistulas, sinus tracts, fenestrations, and scarring, as well as knife cut ulcers in the inguinal, genitocrural, and interlabial folds. Differentiation of HS from Crohn's disease depends upon a previous history of gastrointestinal involvement by the latter but, as noted above, there may be association between the two disorders.
HS shares several features with acne: follicular hyperkeratinization leading to occlusion, fistulous tracts, scarring, and comedome-like lesions. However, acne is a disease of the sebaceous follicles and sebum production; it is responsive to medical therapy. By comparison, HS is due to suppurative inflammation of androgen sensitive terminal hair follicles with secondary involvement of apocrine, eccrine, and sebaceous glands. It is a chronic relapsing inflammatory process, poorly responsive to medical or surgical therapy. Propionibacterium acnes is universally present in acne lesions, but is not isolated in HS. Treatment of HS has been difficult and unsatisfactory in the past. Treatment now is directed at prevention of new lesions through medical management and elimination of existing lesions. Medical therapies, including antibiotics, antiandrogens, and retinoids, have better success in prevention or treatment of early isolated lesions; established sinus tracts and extensive lesions of advanced cases respond only to en bloc surgical excision. There are no data to recommend one medical treatment over another.
Antibiotics may diminish odor and reduce pain, but there is no evidence that long-term antibiotic therapy alters the natural history of HS. Relapse is almost inevitable after withdrawal of medication.
The author has successfully prevented recurrent groin and vulvar lesions in five women by discontinuing oral contraceptive pills with highly androgenic progestins in favor of ethinyl estradiol/drospirenone (Yasmin), combined with the antiandrogenic action of spironolactone 50 to 100 mg at bedtime.
Isotretinoin (2 mg/kg/day in divided doses) is also a useful adjunctive treatment to reduce inflammation before and after surgery, but is not effective against epithelial sinus tracts.Wide excision Wide excision (margins well beyond the clinical borders of disease activity) of involved areas is the most effective treatment of chronic and extensive disease; tissue should be removed down to soft, normal tissue.
The best method of skin closure is controversial. Primary closure and rotation flaps are usually not possible because of the extensive nature of the excision. Grafting in the perineal and perianal areas is associated with high failure rates. Healing by secondary intention has shown good results, but wound closure may take months.
Have a high index of suspicion for the disease in women with recurrent boils in apocrine areas after puberty, despite antibiotic therapy. Premenstrual exacerbation of lesions is also typical of HS.
Educate the patient about the course of HS and encourage consistent follow-up to provide early treatment of lesions. I emphasize the importance of loose underwear since mechanical friction appears to exacerbate the disease.
For women with a few isolated lesions without sinus tracts and ongoing formation of new lesions, I prescribe topical clindamycin (1 percent lotion twice per day for three months), spironolactone (25 mg daily for three months), and the oral contraceptive pill ethinyl estradiol drospirenone (Yasmin) because drospirenone has antiandrogenic effects. I avoid depot medroxyprogesterone acetate, progestin-only pills and pills with a highly androgenic progestin. I inject isolated persistent lesions with triamcinolone.
For women with multiple lesions and sinus tracts, I give isotretinoin (2 mg/kg/day in divided doses) for six months. The sinus tracts should be unroofed and debrided when the disease remits (ie, no new lesions). Clindamycin, spironolactone, and oral contraceptive pills can be given for three months after completion of isotretinoin with follow-up monitoring every six months. The recurrence rate for severe disease is high even after radical surgery. In a series of 82 such patients, as an example, the recurrence rate for inguinoperineal disease was 37 percent. In addition, almost one-quarter of recurrences developed at a previously unaffected site.