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Skin lesion of blastomycosis

A skin lesion of blastomycosis is a symptom of an infection with the fungus Blastomyces dermatitidis. The skin becomes infected as the fungus spreads throughout the body. Another form of blastomycosis is only on the skin and usually gets better on its own with time. This article deals with the more widespread form of the infection.

Causes of Skin lesion of blastomycosis

Blastomycosis is a rare fungal infection. It is most often found in:

  • Africa
  • Canada
  • Central and southeastern United States
  • India
  • Israel
  • Saudi Arabia

A person gets infected by breathing in particles of the fungus that are found in moist soil, especially where there is rotting vegetation. People with immune system disorders are at highest risk for this infection.

The fungus enters the body through the lungs and infects them. In some people, the fungus then spreads (disseminates) to other areas of the body. The infection may affect the skin, bones and joints, genitals and urinary tract, and other systems. Skin symptoms are a sign of widespread (disseminated) blastomycosis.

Skin lesion of blastomycosis Symptoms

Skin symptoms occur in about 80% of people whose blastomycosis infection spreads beyond their lung.

Papules, pustules, or nodules are most frequently found on exposed body areas.

  • They may look like warts or ulcers.
  • They are usually painless.
  • They may vary from gray to violet in color.

The pustules may:

  • Form ulcers
  • Bleed easily
  • Occur in the nose or mouth

Over time, these skin lesions can lead to scarring and loss of skin color (pigment).

Tests and Exams

The infection is diagnosed by identifying the fungus in a culture taken from a skin lesion. This usually requires a skin biopsy.

Treatment of Skin lesion of blastomycosis

This infection is treated with antifungal drugs such as amphotericin B, itraconazole, ketoconazole, or fluconazole. Either oral or intravenous (directly in the vein) drugs are used, depending on the form and stage of the disease.

Prognosis (Outlook)

What happens depends on the form of blastomycosis and the person's immune system. People with a suppressed immune system may need long-term treatment to prevent symptoms from coming back.

Potential Complications

  • Abscesses (pockets of pus)
  • Another (secondary) skin infection caused by bacteria
  • Complications related to medicines (for instance, amphotericin B can have severe side effects)
  • Spontaneously draining nodules

When to Contact a Health Professional

Some of the skin problems caused by blastomycosis can be similar to skin problems caused by other illnesses. Tell your heath care provider if you develop any worrisome skin problems.


Kauffman CA. Blastomycosis. In: Goldman L, Shafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 342.

Review Date: 11/3/2014
Reviewed By: Richard J. Moskowitz, MD, dermatologist in private practice, Mineola, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
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