What is Hidradenitis suppurativa?

Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a chronic, inflammatory, recurrent, debilitating skin follicular disease characterized by painful deep-seated, inflamed lesions in apocrine gland-bearing areas of the body, most commonly the axillary, inguinal, and anogenital regions. 1

Definition and Epidemiology

HS typically presents after puberty with:

• Painful nodules, abscesses, sinus tracts, and scarring in flexural areas
• Characteristic paired comedones
• Chronic and recurrent nature

The prevalence is approximately 1-4% in the UK population, with onset typically in the second to fourth decades of life. 1 There is a female predominance (3:1 female to male ratio) and strong associations with:

• Obesity (odds ratio of 33)
• Smoking (odds ratio of 36)
• Higher prevalence among African-American and biracial individuals (3-fold and 2-fold greater than in white individuals) 1

Clinical Presentation

HS manifests with several characteristic lesions:

• Comedones (characteristically paired)
• Papules and pustules
• Nodules and cysts
• Abscesses and sinus tracts
• Fistulae and scarring

The disease primarily affects:

• Axillae (armpits)
• Groin and perineum
• Buttocks
• Medial thighs
• Submammary region
• Abdominal fold
• Posterior auricular region

Patients experience:

• Severe pain
• Pruritus (itching)
• Chronic discharge (serous, purulent, or blood-stained)
• Persistent malodor
• Reduced mobility in long-standing cases due to fibrosis and dermal contractures 1

Disease Severity Classification

Hurley staging is the most commonly used classification system:

• Stage I: Recurrent nodules and abscesses with minimal scarring
• Stage II: One or a limited number of sinuses and/or scarring within a body region
• Stage III: Multiple or extensive sinuses and/or scarring 1

Other assessment tools include:

• Inflammatory lesion counts
• Pain visual analog scale (VAS)
• Dermatology Life Quality Index (DLQI)
• Hidradenitis Suppurativa Clinical Response (HiSCR) 1

Pathogenesis

HS is primarily a disease of follicular occlusion with complex pathophysiology:

• Follicular hyperkeratosis and occlusion is the initial event
• Genetic factors play a role (up to 42% report family history)
• Mutations in γ-secretase genes (NCTSN, PSEN1, PSENEN) in some familial cases
• Dysregulated inflammatory response with significant involvement of TNF-α
• Hormonal influences suggested by female predominance, post-pubertal onset, and premenstrual flares
• Environmental factors including obesity and smoking contribute to disease development 1

Comorbidities and Complications

HS is associated with several important comorbidities:

• Nearly doubled risk of cardiovascular-associated death
• Type 2 diabetes, hyperlipidemia, and hypertension
• Depression and increased suicide risk
• Association with Crohn's disease (but not ulcerative colitis)
• Pilonidal sinus and acne vulgaris 1

Complications include:

• Fistula formation affecting urethra, bladder, or rectum
• Lymphedema
• Anemia
• Squamous cell carcinoma in chronic lesions 1

Management Approach

Treatment should be tailored to disease severity:

Mild Disease (Hurley Stage I)

• Topical clindamycin 1% solution twice daily for affected skin regions 1
• Oral tetracyclines (lymecycline 408 mg or doxycycline 100 mg once or twice daily) for 12 weeks 1
• Pain management with NSAIDs as needed 1

Moderate Disease (Hurley Stage II)

• Clindamycin 300 mg + rifampicin 600 mg orally for 10-12 weeks 1
• Consider treatment break after this regimen to assess need for ongoing therapy 1

Severe Disease (Hurley Stage III)

• Adalimumab (160 mg at week 0,80 mg at week 2, then 40 mg weekly) 1, 2
• Surgical options including extensive excision for refractory cases 1

Additional Therapeutic Options

• Acitretin 0.3-0.5 mg/kg/day (for males and non-fertile females) 1
• Dapsone as an alternative systemic agent 1
• Surgical interventions ranging from incision and drainage to wide excision 1

Lifestyle Modifications

All patients should be advised on:

• Smoking cessation (critical given the strong association)
• Weight management for those with obesity
• Appropriate wound dressings for draining lesions
• Screening for depression and anxiety
• Screening for cardiovascular risk factors (BP, lipids, HbA1c) 1

Key Pitfalls to Avoid

1. Delayed diagnosis: HS is often misdiagnosed as recurrent boils or simple abscesses, delaying appropriate treatment
2. Inadequate treatment duration: Short courses of antibiotics are ineffective; longer courses (10-12 weeks) are needed
3. Focusing only on acute flares: HS requires long-term management strategy
4. Overlooking comorbidities: Screening for associated conditions is essential
5. Relying solely on medical or surgical therapy: Combined approaches are often necessary for optimal outcomes

Remember that HS significantly impacts quality of life, with patients experiencing physical pain, psychological distress, and social isolation due to symptoms. Early recognition and appropriate management are crucial to minimize disease progression and improve outcomes.