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

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. A person gets infected by inhaling fungal particles that are found in moist soil, particularly amongst rotting vegetation. People with immune system disorders are at highest risk for this infection.

The lungs are the point 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. The infection may affect the skin, bones and 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. They may affect the nose and mouth as well.

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

The diagnosis is based on culture of the fungus from the skin lesion. This 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 drugs may be used.

The outlook depends on the form of blastomycosis and the immune system status of the individual. In immunosuppressed individuals, long-term therapy may be required to prevent repeat infections.

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

The skin problems resulting from 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.