Excerpt from Hidradenitis Suppurativa

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Background

Hidradenitis suppurativa (HS) is a disorder of the terminal follicular epithelium in the apocrine gland–bearing skin. HS is characterized by comedolike follicular occlusion, chronic relapsing inflammation, mucopurulent discharge, and progressive scarring.

Pathophysiology

HS has traditionally been considered a disorder of the apocrine glands. HS was first described as a distinct entity in 1839, when Velpeau¹ reported a patient with the superficial abscess formation in the axillary, mammary, and perianal regions. In 1854, Verneuil² associated the suppurative process with the sweat glands, and the condition was given its current name. For many years, the condition was described as Verneuil disease, but it subsequently became known as HS. Verneuil did not perform any histopathologic studies, and he conceded that his conclusions were based purely on the characteristic distribution of the condition.

In 1922, Schiefferdecker³ classified the sweat glands as eccrine and apocrine, and he subsequently localized HS to the apocrine glands. In 1939, Brunsting⁴ provided a detailed description of the histologic features of HS. He observed the primary cellular reaction in the lumen of the apocrine glands and in the neighboring periglandular connective tissue. Detailing the clinical features of the disease, Brunsting⁴ highlighted its frequent association with acne. He noted that HS, dissecting cellulitis of the scalp and neck, and acne conglobata commonly occur in the same patient. He thought that the central pathogenetic event in all 3 conditions was a tendency for follicular hyperkeratinization with secondary bacterial infection.

In 1956, Pillsbury et al⁵ combined acne conglobata, HS, and dissecting cellulitis under the term follicular occlusion triad. The only flaw in their concept was the focus on apocrine sweat gland involvement. In 1975, Plewig and Kligman⁶ added pilonidal sinus as another component to the ensemble, and they introduced the term acne tetrad. Plewig and Kligman pointed out that HS is a misnomer because of the lack of apocrine gland involvement, but they did not present a detailed explanation. In 1989, Plewig and Steger⁷ suggested the term acne inversa as an inclusive and accurate name for what was previously called the follicular occlusion triad, or follicular occlusion tetrad. Eventually, HS was accepted as an acneiform disorder that begins with follicular occlusion rather than an infection of the sweat glands.

Because HS is actually a defect of follicular epithelium, some authorities have suggested excluding all outdated synonyms for this disease, including HS, and substituting the term acne inversa. The term acne inversa links the pathogenesis to acne and reflects the fact that the condition is an expression of follicular occlusion in localizations inverse to acne vulgaris.

Frequency

United States

In the United States, the prevalence of HS appears to be 1-2% in the general population.

International

The prevalence of HS appears to be 1% of the general population; it was 4% in a group of young adults who were treated at a clinic for sexually transmitted diseases. HS is probably more common than once thought, but the diagnosis is frequently ignored or missed. HS has a worldwide distribution, although hot, humid environments tend to support its development.

Mortality/Morbidity

The death rate is similar to that in the general adult population. Although rare complications of the disease are described, little is known about the typical effects of HS. HS is a chronic disabling disorder that relentlessly progresses and leads to keloids, contractures, and immobility. Patients can become outcasts or at least have difficulty making social contact.

• In an assessment of socioeconomic effects, Jemec et al⁸ noted that the most common problem in both sexes was soreness and that the average patient lost 2.7 days of work per year. In comparison, in Denmark, the average number of work days lost for all reasons was 7.5 days per year per employed person, whereas patients with eczema used 4 weeks of sick leave per year because of their disease. Although HS entails less morbidity than perhaps hand eczema, with regard to its prevalence, it significantly contributes to the average number of work days lost (Danish National Statistical Office, Copenhagen, Denmark, Jemec GB, written communication, 1996).


• Jemec et al⁸ also found sex differences in morbidity. Women lost significantly more days of work (mean, 2.9 d) than men (mean, 1.7 d); this finding suggests that women have either a more fulminant course or other contributing factors. On the other hand, male patients experienced less delay in seeking care from a specialist or hospital; this finding could also suggest a more fulminant course or the presence of confounding factors.


• The general self-reported level of health, which is well correlated with more objective parameters of morbidity, is significantly worse among HS patients than among healthy control subjects.


• The mean Dermatology Life Quality Index score for HS is higher than for previously studied skin diseases and correlated with disease intensity as expressed by lesions per month. This suggests that the Dermatology Life Quality Index score may be a relevant outcome measure in future therapeutic trials in HS patients.

Race

• Although many authors report no racial predilection, an increased frequency is observed in blacks, possibly because blacks have a greater density of apocrine glands than whites.

Sex

• Although HS is widely considered to occur more frequently in females than in males, with a ratio as high as 2-5:1, reports on sex prevalence are controversial.
• Active genitofemoral lesions occur significantly more often in female patients, whereas perianal involvement tends to be more common in men. No sex difference is seen in the axillary lesions. Large multiheaded comedones are characteristic findings of the disease. Comedones have been suggested as precursor lesions for HS. They appear to be equally distributed in both sexes and sites.

Age

• The onset of HS peaks in individuals aged 11-50 years, with an average patient age of 23 years.
• In less than 2% of patients, the disease appears before age 11 years.
• In extremely rare cases, HS occurs before puberty or after menopause.

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