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Dermatology

Hidradenitis Suppurativa

Also known as: Acne Inversa

A chronic, painful skin condition causing recurring boils and tunnels under the skin, usually in the armpits and groin.

Source: AAD Hidradenitis Suppurativa Guidelines

Updated: Aug 13, 2026

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Red Flag Warning & Emergency Situations

Rapid spreading erythema indicating secondary cellulitis.

Emergency Management: Severe acute abscess requiring urgent incision and drainage for pain relief.

Core Definition:

Hidradenitis suppurativa (HS) is a chronic, autoinflammatory disorder of the terminal hair follicles in intertriginous areas (axillae, groin, perineum), characterized by recurrent painful nodules, abscesses, and sinus tracts.

Detailed Overview

HS begins with follicular hyperkeratosis leading to occlusion and rupture of the pilosebaceous unit. The release of follicular contents into the dermis triggers an intense immune response. Severe pain and purulent drainage severely impact quality of life.

Epidemiology & Demographics

Prevalence is roughly 1%. More common in women (3:1) and usually presents post-puberty.

Etiological Mechanism

Multifactorial: genetic susceptibility, immune dysregulation, and environmental factors.

Primary Causes

Follicular occlusion and autoinflammation

Tobacco smoking: Highly associated with incidence and severity.
Obesity: Increases mechanical friction and systemic inflammation.

Primary defect is hyperkeratosis of the infundibulum. The follicle occludes, dilates, and ruptures, spilling keratin and bacteria. This triggers a massive innate and adaptive immune response (TNF-alpha, IL-17). Chronic inflammation causes sinus tract formation and hypertrophic scarring.

Characteristic Clinical Presentation

Painful nodules: Deep-seated, tender lumps.
Foul-smelling discharge: Pus draining from abscesses and tunnels.

Physical Examination Signs

Double-comedones (tombstone comedones).
Erythematous, fluctuant abscesses in axillae/groin.
Rope-like scarring.

Clinical Risk: Uncontrolled or untreated conditions may progress to the following complications:

Contractures: Reduced mobility due to scarring.
Squamous Cell Carcinoma: Rarely arises in chronic perineal lesions.

Diagnostic Criteria & Guidelines

Clinical diagnosis based on typical lesions (nodules/sinuses), typical locations (intertriginous), and chronicity (≥2 relapses in 6 months).

Differential Diagnosis

Cutaneous Crohn's disease
Furunculosis
Epidermoid cysts

Laboratory Tests & Biomarkers

CRP/ESR: Elevated during flares.

Imaging Modalities & Findings

Cutaneous Ultrasound:

Hurley Stage I
Abscesses without sinus tracts or scarring.
Hurley Stage II
Recurrent abscesses with tract formation and scarring.
Hurley Stage III
Diffuse involvement with interconnected tracts across an entire area.

First-Line Treatment:

Hurley I: Topical Clindamycin 1% BID. Hurley II: Doxycycline 100 mg PO BID for 12 weeks for anti-inflammatory effect.

Second-Line & Adjunctive Therapy

Adalimumab 160 mg SQ day 1, 80 mg day 15, then 40 mg SQ weekly.

Surgical & Procedural Management

Deroofing of isolated sinus tracts. Wide local excision with grafting for Hurley III.

Recommended Lifestyle Changes

Smoking cessation.
Weight loss.
Use of chlorhexidine wash.

Patient Counseling & Advice

Explain that it is not contagious and not due to poor hygiene. Emphasize smoking cessation as critical for treatment success.

Follow-Up & Monitoring Schedule

Dermatology follow up every 3 months. Screen for depression (PHQ-9).

Preventive Strategies

Strict avoidance of smoking and weight control to prevent disease progression.

Chronic, relapsing course. Surgical excision of affected areas offers the best chance of local cure.

Frequently Asked Questions

No, it is an immune-mediated disorder of the hair follicle.

Authoritative Sources & Evidence References

AAD Hidradenitis Suppurativa Guidelines:
View Official Guideline

Key Literature & References:

Evidence North American clinical management guidelines for hidradenitis suppurativa