Histoplasmosis is a widespread fungal infection which occurs worldwide. In the US, it is most common in the southeastern, mid-Atlantic, and central states. The lungs are the portal of entry for this infection.

Histoplasma grows as a mold in soil, and infection results from inhalation of airborne fungal particles. Soil contaminated with bird or bat droppings may have a higher concentration of mold.

The skin lesions of histoplasmosis are varied and can be caused by an immune reaction to acute pulmonary (lung) involvement. In this case, lesions called erythema nodosum or erythema multiforme (target lesions) occur.

Skin lesions can also be a manifestation of disseminated histoplasmosis, where the fungus has spread to distant organs throughout the body including the skin, the bone marrow and the brain amongst others. Disseminated histoplasmosis is most common amongst immunosuppressed people, such as those with AIDS.

• Skin lesion
  • Oral ulcer -- usually painless
  • Papule, pustule, or nodule -- may be found throughout the body
• Erythema nodosum -- may be seen in individuals with acute lung involvement
• Erythema multiforme (target lesions) -- may be seen in individuals with acute lung involvement

If the skin lesion is seen in the setting of disseminated histoplasmosis, a biopsy of the skin lesion may show the associated fungus. Other findings such as erythema nodosum and erythema multiforme are manifestations of the body's inflammatory reaction and usually do not have fungus in them.

• Secondary (bacterial) skin infection
• Complications of medications (For instance, amphotericin B can have severely unpleasant side effects.)

The skin manifestations of histoplasmosis are varied and may be similar to skin findings seen in other infections or illnesses. Notify your health care provider if you develop any suspicious lesions on your skin so that you may be appropriately evaluated.