Causes and Risks:

Histoplasmosis is a widespread fungal infection which occurs worldwide. In the United States, 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 may result as an inflammatory reaction to acute pulmonary involvement (lung involvement) and present as lesions called erythema nodosum or erythema multiforme (target lesions). Skin lesions may also be a manifestation of disseminated (widespread) histoplasmosis, where the fungi has seeded distant organs throughout the body including skin, bone marrow, brain among others. Disseminated histoplasmosis is most common among the immunosuppressed individuals such as those with AIDS.

Prevention: Prevention of histoplasmosis involves minimizing exposure to dust in contaminated environments -- such as chicken coops and bat caves. Wear protective equipment such as masks if you work in these environments.

Symptoms:

• 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

Signs and Tests:

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 show fungus in them.

Treatment: The mainstay of treatment includes antifungal agents such as amphotericin B, itraconazole, ketoconazole among others. Antifungals may be given intravenously depending on the form/stage of disease. In individuals with disseminated disease, long term suppression with oral antifungal agents may be used.

Prognosis: Prognosis depends on the clinical form of histoplasmosis and the immune system status of the individual. Mortality is highest in disseminated histoplasmosis.

Complications:

• secondary (bacterial) skin infection

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 skin findings so that you may be appropriately evaluated.