A 12-year-old Hispanic girl, accompanied by her mother, presents with a 1-year history of a red irritated rash in both axillae (Figure 102-1). She has been seen by multiple physicians and has tried many antifungal creams with no results. Even hydrocortisone did not help. She had stopped wearing deodorant for fear that she was allergic to all deodorants. Although the rash barely fluoresced at all, the physical examination and history were most consistent with erythrasma. The patient was given a prescription for oral erythromycin and the erythrasma cleared to the great delight of the patient and her mother.

Erythrasma is a chronic superficial bacterial skin infection that usually occurs in a skin fold.

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  The incidence of erythrasma is approximately 4 percent.¹

  
  
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  Both sexes are equally affected.

  
  
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  The inguinal location is more common in males.

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  Corynebacterium minutissimum, a lipophilic Gram-positive non–spore-forming rod-shaped organism, is the causative agent.

  
  
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  Under favorable conditions, such as heat and humidity, this organism invades and proliferates the upper 1/3 of the stratum corneum.

  
  
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  The organism produces porphyrins that result in the coral red fluorescence seen under a Wood lamp (Figure 102-2).

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  Warm climate.

  
  
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  Diabetes mellitus.

  
  
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  Immunocompromised states.

  
  
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  Obesity.

  
  
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  Hyperhidrosis.

  
  
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  Poor hygiene.

  
  
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  Advanced age.

Clinical Features