Hidradenitis Suppurativa (Acne Inversa)

Hidradenitis suppurativa (HS) is a chronic, relapsing inflammatory disease of hair follicles in intertriginous regions, characterized by painful nodules, abscesses, double-ended comedones, sinus tracts, and scarring. Pathogenesis involves follicular occlusion, dysregulated innate/adaptive immunity (IL-1, TNF, IL-17 axes), microbiome shifts, mechanical stress, and hormonal/metabolic factors. Disease burden is high with pain, drainage, malodor, and psychosocial impact. Management is staged: lifestyle and skin care, antiseptics, antibiotics, intralesional steroids, hormonal therapies, biologics (notably TNF and IL-17 inhibitors), surgery, and adjunct pain/wound care.

Epidemiology

  • Prevalence ~0.1–1%; onset in adolescence/early adulthood; female predominance.
  • Risk factors: family history (~30–40%), smoking, obesity/metabolic syndrome, mechanical friction.
  • Common sites: axillae, groin, perineal, inframammary, buttocks.

Pathophysiology

  • Primary event: follicular occlusion and rupture with keratinous/follicular spill triggering inflammation.
  • Cytokines: TNF-α, IL-1β, IL-17/23, IL-36; biofilms in sinus tracts.
  • Comorbidities: metabolic syndrome, depression, spondyloarthritis, IBD (especially Crohn), PCOS, pilonidal disease.

Clinical Features and Staging

  • Lesions: tender deep nodules, abscesses, draining tunnels (sinus tracts), double comedones, rope-like scars.
  • Hurley staging:
    • I: abscesses without sinus tracts/scarring.
    • II: recurrent abscesses with widely separated tracts/scars.
    • III: diffuse involvement with interconnected tracts.
  • Severity indices: IHS4, HiSCR for clinical response in trials.

Diagnosis and Differential

  • Clinical diagnosis: typical lesions, locations, chronicity.
  • Rule out: furunculosis, carbuncles, cutaneous Crohn disease, actinomycosis, pilonidal cysts, acne conglobata, Fox-Fordyce disease.

Management

  1. Lifestyle and skin care
  • Smoking cessation; weight management; friction and heat minimization; breathable clothing.
  • Antiseptic washes (chlorhexidine, benzoyl peroxide), dilute bleach soaks; avoid aggressive shaving; gentle depilation options.
  • Pain control: NSAIDs, acetaminophen; avoid chronic opioids; neuropathic agents for chronic pain; consider pain specialist.
  1. Medical therapy
  • Intralesional triamcinolone for acute nodules.
  • Antibiotics:
    • Topical clindamycin 1% for mild disease.
    • Oral tetracyclines (doxycycline 100 mg bid) for 8–12 weeks; macrolides as alternatives.
    • Combination clindamycin 300 mg bid + rifampin 300 mg bid for 8–12 weeks in moderate disease; monitor LFTs/interactions.
    • Moxifloxacin + metronidazole + rifampin regimens for refractory disease (specialist oversight).
  • Hormonal therapy (female patients):
    • Combined OCPs, spironolactone (50–200 mg/day), finasteride; consider PCOS evaluation.
  • Biologics and targeted agents:
    • Adalimumab: only FDA/EMA-approved biologic for HS; weekly dosing; aim for HiSCR response.
    • Infliximab off-label for severe HS, especially with IBD overlap.
    • IL-17A inhibitors: secukinumab approved in many regions (2023–2025) for moderate–severe HS; ixekizumab under study/used off-label.
    • IL-1 pathway (anakinra), IL-23 inhibitors (guselkumab, risankizumab) show promise in refractory cases.
    • JAK inhibitors under investigation.
  • Short oral corticosteroids for acute severe flares; avoid long-term monotherapy.
  1. Procedures and surgery
  • Incision and drainage for fluctuant abscesses (temporizing; recurrence common).
  • Deroofing of sinus tracts for localized tunnels (effective and tissue-sparing).
  • Wide local excision with secondary intention or grafts/flaps for Hurley II–III disease; combine with perioperative biologic therapy for best outcomes.
  • Laser hair removal (Nd:YAG) can reduce flares in selected sites; CO2 laser excision/deroofing options.
  1. Multidisciplinary and supportive care
  • Wound care (absorbent dressings, negative pressure for large defects).
  • Psychological support, depression screening; social work for work accommodations.
  • Screen/treat comorbidities: IBD, spondyloarthritis, metabolic syndrome.

Prognosis

  • Chronic relapsing course; earlier intervention can prevent tunneling/scarring.
  • Combined medical-surgical strategies improve long-term control.

References (recent guidelines and key reviews)

  • North American HS Guidelines (AAD/HS Foundation), 2022–2024 updates.
  • European S1/S2k HS guidelines, 2023–2024.
  • RCTs and real-world studies for adalimumab, secukinumab, and surgical outcomes, 2021–2025.

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