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.
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. 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 occur in about 80% of people infected with blastomycosis. It is a sign of widespread (disseminated) infection. Skin lesions may look like warts or like ulcers. They may also affect the nose and mouth.