8th June 2025

Diagnosis

History and Examination

• Onset
  • 18-39 years of age usually 
• Site
  • Intertriginous skin of axillary, groin, perianal, perineal and inframammary regions
• Double- headed open comedones
• Inflamed nodules 
  • Solitary lesion initially before multiple sites affected
  • Recurrences common 
  • Develop into pustules and rupture with purulent discharge
• Abscesses 
• Sinus tracts or fistulae (draining skin tunnels) 
  • Chronic as recurrence in same regions 
• Scar formation 
  • Due to healing with dense fibrosis 
• Discomfort or pain which can be severe
• Malodour
• Disfigurement
• Reduced quality of life

Image Source: Wikimedia Commons (2012). Lesions from Hidradenitis Suppurativa, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Lesions_from_hidradenitis_suppurativa.jpg (Accessed 23 May 2025).

Classification 

Severity of HS can be classified using Hurley staging which can help guide the type of treatment.

• Hurley Stage 1 (mild) – single or multiple, discrete abscesses and inflammatory nodules. There is no scarring or sinus tract formation.
• Hurley Stage 2 (moderate) – single or multiple, discrete abscesses and inflammatory nodules. There is scarring and widely separated sinus tracts. 
• Hurley Stage 3 (severe) – multiple and extensive interconnected scars with or without active inflamed lesions.

Investigation

Hidradenitis suppurativa is a clinical diagnosis based on symptoms and signs. However, the following investigations may be useful:

• Bacterial swab – usually negative 
• Blood tests if secondary infection is suspected or to exclude diabetes mellitus
• Skin biopsy – occasionally undertaken to exclude squamous cell carcinoma and differentiate from other inflammatory diseases such as Crohn’s disease. 
• MRI scan – used in severe disease to check sinus tract path and plan surgery.