Physical Examination Findings of Hidradenitis Suppurativa
On physical examination, hidradenitis suppurativa presents with painful inflammatory nodules, abscesses, sinus tracts, bridged scars, and characteristically paired open comedones (double-headed comedones) in flexural areas, most commonly the axillae, groin, perineum, buttocks, submammary folds, and anogenital regions. 1
Primary Lesion Types
The physical exam reveals a spectrum of lesions depending on disease stage and chronicity:
Early/Active Inflammatory Lesions
- Painful subcutaneous nodules - deep-seated, tender inflammatory nodules that are the hallmark of active disease 2, 3
- Abscesses - fluctuant collections that may spontaneously rupture and drain thick, mucopurulent, foul-smelling fluid 1, 3
- Open comedones - characteristically paired or "double-headed" comedones that are pathognomonic for HS 1, 4
- Papules and pustules - smaller inflammatory lesions in affected areas 1
Chronic/Late-Stage Lesions
- Sinus tracts - tunneling connections between lesions that may actively drain serous, purulent, or blood-stained fluid 1
- Bridged scars - rope-like fibrotic subcutaneous scarring connecting previous lesion sites 1
- Dermal contractures - fibrotic changes that can restrict mobility of affected limbs 1
- Tombstone comedones - a specific finding noted in chronic disease 4
Anatomical Distribution
The disease targets specific intertriginous and flexural sites 2, 1:
- Axillae (most common site) 2, 3
- Groin and inguinal regions 2, 1
- Perineum and perianal area 1
- Buttocks and gluteal region 1
- Submammary/inframammary folds 1
- Medial thighs 1
- Abdominal folds 1, 4
- Posterior auricular region (less common) 1
Associated Physical Findings
Discharge Characteristics
- Chronic purulent drainage - persistent discharge from active lesions and sinus tracts 1
- Foul-smelling odor - persistent malodor from chronic drainage 1
- Serous or blood-stained discharge may also be present 1
Complications on Exam
- Fistula formation - may involve urethra, bladder, or rectum in severe cases 1
- Lymphoedema - secondary to chronic inflammation and scarring 1
- Squamous cell carcinoma - rare but important complication in long-standing disease 1
Severity Assessment on Physical Exam
Use the Hurley staging system for baseline severity assessment 1:
- Hurley Stage I: Recurrent nodules and abscesses with minimal scarring, no sinus tracts 2
- Hurley Stage II: One or limited number of sinuses and/or scarring within a body region 2
- Hurley Stage III: Multiple or extensive sinuses and/or scarring across a body region 2
Quantitative Assessment
Count and document 1:
- Number of inflammatory nodules
- Number of abscesses
- Number of draining sinuses
- Extent of scarring
- Surface area affected
Clinical Pitfalls
A common diagnostic delay of 3-7 years occurs because early lesions may be mistaken for simple boils or folliculitis 4, 5. The key distinguishing features are:
- Recurrence - lesions repeatedly occur in the same anatomical sites 2, 1
- Chronicity - persistent or recurring disease pattern 1
- Characteristic comedones - the paired/double-headed comedones are pathognomonic 1, 4
Subclinical lesions may not be apparent on visual inspection alone - ultrasonography can detect hidden inflammatory changes and sinus tracts not visible on surface examination, with studies showing 56.9% of patients having subclinical lesions 5.