A 17-year-old teenager presents with new tender lesions in her axilla that started during her period 2 weeks ago (Figure 98-1). She has had two similar outbreaks in the axilla the year before. The clinician determined that the diagnosis was a mild case of hidradenitis suppurativa with folliculitis as an alternative diagnosis to be considered. The patient was started on doxycycline 100 mg twice daily and the condition cleared within 1 month. The patient was also a one pack per day smoker and she agreed to quit smoking for her health and to decrease her risk of further outbreaks of hidradenitis.

Hidradenitis suppurativa (HS) is an inflammatory disease of the pilosebaceous unit in the apocrine gland-bearing skin. HS is most common in the axilla and inguinal area, but may be found in the inframammary area as well. It produces painful inflammatory nodules, cysts, and sinus tracks with mucopurulent discharge and progressive scarring.

It is called acne inversa because it involves intertriginous areas and not the regions affected by acne (similar to inverse psoriasis).

• 
  

  Occurs after puberty in approximately 1 percent of the population.¹

  
  
• 
  

  Incidence is higher in females, in the range of 4:1 to 5:1. Flare-ups may be associated with menses.¹

• 
  

  Disorder of the terminal follicular epithelium in the apocrine gland-bearing skin.¹

  
  
• 
  

  Starts with occlusion of hair follicles that lead to occlusion of surrounding apocrine glands.

  
  
• 
  

  Chronic relapsing inflammation with mucopurulent discharge.

  
  
• 
  

  Can lead to sinus tracts, draining fistulas and progressive scarring.

Obesity, smoking, and tight-fitting clothing.

Clinical Features

• 
  

  Most common presentation is painful, tender, firm, nodular lesions in axillae (Figures 98-1 and 98-2).

  
  
• 
  

  Nodules may open and drain pus spontaneously and heal slowly, with or without drainage, over 10 to 30 days.¹

  
  
• 
  

  Nodules may recur several times yearly, or in severe cases new lesions form as old ones heal.

  
  
• 
  

  Surrounding cellulitis may be present and require systemic antibiotic treatment.

  
  
• 
  

  Chronic recurrences result in thickened sinus tracts, which may become draining fistulas (Figures 98-3).

  
  
• 
  

  HS can cause disabling pain, diminished range of motion, and social isolation.