A practical guide to hidradenitis suppurativa

Genetic predisposition. As many as 40% of patients with HS report having at least 1 affected family member. A positive family history of HS is associated with earlier onset, longer disease duration, and severe disease.²² HS is genetically heterogeneous, and several mutations (eg, gamma secretase, PSTPIP1, PSEN1 genes) have been identified in patients and in vitro as the cause of dysregulation of epidermal proliferation and differentiation, immune dysregulation, and promotion of amyloid formation.^8,23-25

Obesity and metabolic risk factors. There is a strong relationship between HS and obesity. As many as 70% of patients with HS are obese, and 9% to 40% have metabolic syndrome.^12,18,26-28 Obesity is associated with maceration and mechanical stress, increased fragility of the dermo-epidermal junction, changes in cutaneous blood flow, and subdermal fat inflammation—all of which favor the pathophysiology of HS.^29,30

Smoking. Tobacco smoking is associated with severe HS and a lower chance of remission.¹² Population-based studies have shown that as many as 90% of patients with HS have a history of smoking ≥ 20 packs of cigarettes per year.^{1,12,18,31,32} The nicotine and thousands of other chemicals present in cigarettes trigger keratinocytes and fibroblasts, resulting in epidermal hyperplasia, infundibular hyperkeratosis, excessive cornification, and dysbiosis.^8,23,24

Hormones. The exact role sex hormones play in the pathogenesis of HS remains unclear.^8,32 Most information is based primarily on small studies looking at antiandrogen treatments, HS activity during the menstrual cycle and pregnancy, HS exacerbation related to androgenic effects of hormonal contraception, and the association of HS with metabolic-endocrine disorders (eg, polycystic ovary syndrome [PCOS]).^8,33

A family history of hidradenitis suppurativa is associated with earlier onset, longer disease duration, and severe disease.

Androgens induce hyperkeratosis that may lead to follicular occlusion—the hallmark of HS pathology.³⁴ A systematic review looking at the role of androgen and estrogen in HS found that while some patients with HS have elevated androgen levels, most have androgen and estrogen levels within normal range.³⁵ Therefore, increased peripheral androgen receptor sensitivity has been hypothesized as the mechanism of action contributing to HS manifestation.³⁴

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