A histoplasmosis infection, which is caused by the fungus Histoplasma capsulatum, can result in skin lesions.

Histoplasmosis is a widespread fungal infection that occurs worldwide. The infection gets into the body through the lungs.

Histoplasma grows in soil. The fungal particles become airborne, and are breathed into the lung. Soil contaminated with bird or bat droppings may have a higher concentration of the fungus.

The skin lesions can be caused by an immune reaction to the lung infection. In this case, lesions called erythema nodosum or erythema multiforme occur.

Skin lesions can also occur when the fungus has spread to distant organs throughout the body, including the skin, bone marrow, and the brain. This is most common among immunosuppressed people, such people with AIDS.

The symptoms may include:

• Mouth ulcer, usually painless
• Pustules or nodules throughout the body
• Other symptoms related to erythema nodosum and erythema multiforme

In some cases, a biopsy of the skin lesion can identify the fungus. On the other hand, erythema nodosum and erythema multiforme skin lesions are inflammatory reactions and usually do not have fungus in them.