Skin lesions of histoplasmosis are a symptom of widespread infection with the fungus Histoplasma capsulatum.

Histoplasmosis is a fungal infection. It occurs all over the world.

Histoplasma fungus grows in soil. When particles become airborne, they can be breathed into the lungs, causing infection. Soil contaminated with bird or bat droppings may have a higher concentration of the fungus.

After infecting the lungs, the fungus travels (disseminates) to distant organs throughout the body, including the skin, the bone marrow, and the brain. This is most common in immunosuppressed people, such as those with AIDS or cancer, or those who have had a transplant.

Skin lesions can be caused by an immune response to the infection (usually a rash called erythema nodosum or erythema multiforme), or by the fungus itself when it spreads to the skin.