Skin lesion of blastomycosis

A skin lesion of blastomycosis is a symptom of an infection with Blastomyces dermatitidis in which the skin becomes infected as the fungus spreads throughout the body.

Causes, incidence, and risk factors

Blastomycosis is a rare fungal infection that occurs primarily in the central and southeastern states of the US, and in Canada, India, Israel, Saudi Arabia, and Africa. It is acquired by inhaling fungal particles found in moist soil, particularly amongst decaying vegetation. People with immune system disorders are at highest risk.

The lungs are the portal of entry for this infection and are the main organ involved. The fungus may disseminate (spread) to other areas of the body after initial infection in the lungs and affect the skin, bone/joints, genitourinary tract and other systems.

Skin disease is primarily a manifestation of disseminated (widespread) blastomycosis and occurs in up to 80% of individuals. Skin lesions may be wartlike or appear as ulcers and may affect the nose and mouth as well.


  • Papules, pustules, or nodules       o May appear wartlike       o May vary from gray to violet in color.  
  • Subcutaneous nodules  
  • Pustules that ulcerate       o May bleed easily       o May occur in the nose or mouth

With time, these lesions can lead to scarring and loss of skin pigment. The lesions are most frequently found on exposed body areas.

Signs and tests
The diagnosis is based on culture of the fungus from the skin lesion - which usually requires a skin biopsy.

Treatment involves the use of antifungal agents such as amphotericin B, itraconazole, ketoconazole, or fluconazole. Depending on the form and stage of the disease, intravenous or oral agents may be used.

Expectations (prognosis)
Prognosis depends on the form of blastomycosis and the immune system status of the individual. In immuno-suppressed individuals, long-term therapy may be required to prevent recurrence.


  • Secondary bacterial skin infection  
  • Abscesses  
  • Spontaneously draining nodules  
  • Complications related to medications (For instance, amphotericin B can have severely unpleasant side effects.)

Calling your health care provider
The skin manifestations of blastomycosis are varied and may be similar to skin conditions associated with other illnesses. Notify your health care provider if you develop any skin problems that you think are suspicious.

Johns Hopkins patient information

Last revised: December 4, 2012
by Janet G. Derge, M.D.

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