A practical guide to hidradenitis suppurativa

Host-defense defects. HS shares a similar cytokine profile with other well-­established immune-mediated inflammatory diseases, including pyoderma gangrenosum (PG)^36,37 and Crohn disease.^38-40 HS is characterized by the expression of several immune mediators, including tumor necrosis factor-alpha (TNF-alpha), interleukin-1 ­alpha (IL-1 alpha), IL-1 beta, IL-8, IL-17, and the IL-23/T helper 17 pathway, all of which are upregulated in other inflammatory diseases and also result in an abnormal innate immune response.^8,24 The recently described clinical triad of PG, acne, and HS (PASH) and the tetrad of pyogenic arthritis, PG, acne, and HS (PAPASH) further support the role of immune dysregulation in the pathogenesis of HS.⁴⁰ Nonetheless, further studies are needed to determine the exact pathways of cytokine effect in HS.⁴¹

Use these criteria to make the diagnosis

The US and Canadian Hidradenitis Suppurativa Foundations (HSF) guidelines base the clinical diagnosis of HS on the following criteria²:

• Typical HS lesions: Erythematous skin lesions; inflamed, deep-seated painful nodules; “tombstone” double-ended comedones; sinus tracts; scarring; deformity. FIGURES 1A-1E show typical lesions seen in patients with HS.
• Typical locations: Intertriginous regions—apocrine gland–containing areas in axilla, groin, perineal region, buttocks, gluteal cleft, and mammary folds; beltline and waistband areas; areas of skin compression and friction.
• Recurrence and chronicity: Recurrent painful or suppurating lesions that appear more than twice in a 6-month period.^2,41-43

Patients with HS usually present with painful recurrent abscesses and scarring and often report multiple visits to the emergency department for drainage or failed antibiotic treatment for abscesses.^15,44

Ask patients these 2 questions. Vinding et al⁴⁵ developed a survey for the diagnosis of HS using 2 simple questions based on the 3 criteria established by the HSF:

1. “Have you had an outbreak of boils during the last 6 months?” and
2. “Where and how many boils have you had?” (This question includes a list of the typical HS locations—eg, axilla, groin, genitals, area under breast.)

In their questionnaire, Vinding et al⁴⁵ found that an affirmative answer to Question 1 and reports of > 2 boils in response to Question 2 correlated to a sensitivity of 90%, specificity of 97%, positive predictive value of 96%, and negative predictive value of 92% for the diagnosis of HS. The differential diagnosis of HS is summarized in TABLE 1.^42,45-52

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