Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a chronic, recurrent, inflammatory disease of the follicular unit that causes painful nodules, abscesses, sinus tracts and scarring in the axillae, groin, inframammary and anogenital areas.

• Prevalence is about 1%, with onset after puberty (peak 20 to 30 years), female predominance and higher rates in people of African descent.
• Pathogenesis: follicular occlusion and rupture, innate immune activation (TNF, IL-1, IL-17, IL-23), and dysbiosis. Smoking and obesity are strong aggravating factors, and family history is present in about one third.
• Associations: metabolic syndrome, PCOS, inflammatory bowel disease, spondyloarthritis, depression, pilonidal disease, acne conglobata.
• Complications: chronic pain, sinus tracts, fistulae, contractures, anaemia of chronic disease, lymphoedema, squamous cell carcinoma in long standing perianal disease, and amyloidosis (rare).

• Deep, tender nodules, abscesses, double ended comedones, draining tunnels, rope like scars.
• Hurley stage I: isolated abscesses without tracts. Stage II: recurrent lesions with tracts and scarring, separated by normal skin. Stage III: diffuse involvement with interconnected tracts.
• Malodorous discharge, pain, and delay to diagnosis of 7 to 10 years.

• Clinical: typical lesions, typical sites, and chronicity with 2 or more recurrences in 6 months.
• Staging with Hurley stage and IHS4 or HiSCR for response.
• Ultrasound defines tracts, fluid collections and subclinical inflammation, and guides surgery.
• Swab culture only for acute superinfection. Exclude boils, Crohn perianal disease, cutaneous tuberculosis, actinomycosis, and epidermoid cysts.
• Assess BMI, HbA1c, lipids, androgen excess, and screen for depression.

• Weight loss, smoking cessation, loose clothing, and analgesia (paracetamol, NSAIDs; avoid long term opioids).
• Mild disease: chlorhexidine wash, topical clindamycin 1% twice daily, resorcinol 15% cream, intralesional triamcinolone 10 mg/mL (0.2 to 2 mL) for acute nodules, and deroofing of recurrent nodules.
• Moderate disease:
  • Doxycycline 100 mg twice daily or lymecycline 408 mg daily for 12 weeks.
  • Clindamycin 300 mg twice daily plus rifampicin 300 mg twice daily for 10 to 12 weeks.
  • Spironolactone 50 to 150 mg, metformin 500 to 1500 mg, or acitretin in selected patients.
• Biologics (moderate to severe):
  • Adalimumab 160 mg week 0, 80 mg week 2, then 40 mg weekly or 80 mg every 2 weeks.
  • Secukinumab 300 mg weekly for 5 weeks, then every 4 weeks (or every 2 weeks if suboptimal).
  • Bimekizumab 320 mg every 2 weeks to week 16, then every 4 weeks.
  • Infliximab 5 to 10 mg/kg every 4 to 8 weeks is an off label alternative.
• Surgery: deroofing or punch debridement for limited disease, wide local excision for Hurley II to III (usually with biologic cover), CO2 laser, and secondary intention healing.
• Screen and treat depression. Wound care with absorbent dressings.