Causes

Blastomycosis is a rare fungal infection. It is most common in the central and southeastern United States, and in Canada, India, Israel, Saudi Arabia, and Africa. A person gets infected by inhaling fungal particles that are found in moist soil, particularly 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, infecting them. In some people, the fungus then spreads (disseminates) to other areas of the body. The infection may affect the skin, bones and joints, genitourinary tract, and other systems. Skin symptoms are a sign of widespread (disseminated) 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).

Exams and Tests

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

Treatment

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.

Outlook (Prognosis)

What happens depends on the form of blastomycosis and the individual's immune system. In immunosuppressed individuals, long-term treatment may be required to prevent symptoms from coming back.

Possible Complications

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

When to Contact a Medical Professional

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

References

Updated: 4/15/2012

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.