What conditions appear similar to vaginal/vulvar hidradenitis suppurativa (HS)?

Differential Diagnosis of Vaginal/Vulvar Hidradenitis Suppurativa

When evaluating vulvar lesions suspected to be hidradenitis suppurativa, you must distinguish it from Fournier gangrene, folliculitis, pilonidal disease, and pyoderma gangrenosum, as these conditions can present with similar suppurative features in the anogenital region. 1

Key Mimickers to Consider

Fournier Gangrene (Most Critical)

• This is the most important condition to rule out immediately as it represents a surgical emergency with high mortality risk 1
• Look for: rapid progression, systemic toxicity (fever, tachycardia, hypotension), crepitus on examination, and necrotic tissue
• Unlike HS, Fournier gangrene progresses over hours to days rather than the chronic recurrent pattern of HS 1

Folliculitis

• Presents with superficial pustules rather than the deep-seated, painful nodules characteristic of HS 1
• Lacks the chronic sinus tracts, bridged scars, and comedones that define HS 1, 2
• Responds rapidly to topical or short-course oral antibiotics, whereas HS requires prolonged management 1

Pilonidal Disease

• While pilonidal disease shares the follicular occlusion pathophysiology with HS, it typically localizes to the sacrococcygeal region rather than vulvar area 3
• Patients with HS have 4.97 to 5.61 times higher odds of having concurrent pilonidal disease (1.4-2.3% prevalence) 3
• Both conditions feature inflammatory nodules and draining tunnels, but anatomic distribution differs 3

Pyoderma Gangrenosum

• Shares clinical features with HS including suppurating plaques, ulcers, and neutrophil-rich inflammation 3
• HS patients have up to 20 times greater odds of having pyoderma gangrenosum (0.2-0.4% prevalence) 3
• Key distinguishing feature: pyoderma gangrenosum typically shows pathergy (lesions worsen with trauma), and ulcers have characteristic violaceous undermined borders 3
• The association is particularly strong (3.7% prevalence) in HS patients with concurrent Crohn's disease 3

Additional Conditions in the Differential

Vulvar Abscesses/Bartholin Cysts

• Bartholin gland abscesses present as acute, unilateral, painful swelling at the posterior introitus 4
• Unlike HS, these are typically isolated events without the chronic recurrent pattern or comedones 4

Granulomatous Diseases

• Crohn's disease can cause vulvar manifestations with fistulas and abscesses 4
• Diagnostic studies for granulomatous disease should be negative in HS 4
• Consider inflammatory bowel disease screening as HS has significant association with Crohn's disease 2

Acne Conglobata

• When occurring in the anogenital region, can mimic HS 5
• Part of the follicular occlusion tetrad along with HS 5
• HS patients have 1.77 to 5.07 times greater odds of having acne vulgaris/conglobata (4.5-15.2% prevalence) 3

Diagnostic Approach to Confirm HS

To establish the diagnosis of vulvar HS, you need all three criteria:

• Typical lesions: painful nodules, abscesses, sinus tracts, bridged scars, or open comedones 1, 2
• Typical location: anogenital region including vulva 1, 2
• Chronicity and recurrence: not a single isolated event 1, 2

Clinical Features That Support HS Diagnosis

• Paired comedones (characteristically doubled) in the affected area 2
• Chronic discharge with persistent malodor 2, 6
• Fibrosis and dermal contractures in long-standing disease 2
• Post-pubertal onset, typically ages 20-30 years 2
• Female predominance (3:1 ratio) 2

Important Clinical Pitfall

• Vulvar HS is frequently misdiagnosed and inadequately treated because patients often present to gynecology first rather than dermatology 7, 4
• The diagnosis is primarily clinical; histopathological confirmation is rarely needed 6
• Biopsy shows follicular hyperkeratosis, follicular occlusion, and keratin-containing cysts, but these features are not specific 6