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Histoplasmosis
See also in: Oral Mucosal Lesion,Pulmonary
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Histoplasmosis

See also in: Oral Mucosal Lesion,Pulmonary
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Contributors: Vivian Wong MD, PhD, Susan Burgin MD, Susan Voci MD, Sumanth Rajagopal MD, William Bonnez MD
Other Resources UpToDate PubMed

Synopsis

Classical histoplasmosis, also known as Darling's disease, small-form histoplasmosis, American histoplasmosis, cave disease, Ohio Valley disease, or reticuloendotheliosis, is a systemic infection caused by the thermally dimorphic fungus Histoplasma capsulatum var. capsulatum. The yeast phase is present in tissue.

Classical histoplasmosis is endemic to the Ohio / Mississippi River Valley, South and Central America, northern South America, Brazil, Argentina, Uruguay, and Paraguay.

Bird and bat excrement enhance the growth of the organism in the soil. Initially, microconidia are inhaled into the lungs where they transform into yeast forms.

There are 3 forms of the disease: pulmonary (acute and chronic), disseminated (acute and chronic), and primary cutaneous histoplasmosis.

Pulmonary:
In acute pulmonary histoplasmosis, the patient presents with cough, chest pain, fever, and occasionally a rash caused by immune complexes (erythema multiforme, toxic erythema, or erythema nodosum) 3-17 days after a prodrome of an influenza-like illness. In immunocompetent patients, acute pulmonary histoplasmosis is most likely asymptomatic or pauci-symptomatic.

Chronic pulmonary histoplasmosis resembles pulmonary tuberculosis and is not usually associated with skin findings. It is most commonly seen in patients with preexisting pulmonary disease.

Disseminated:
In patients with acute disseminated histoplasmosis, the fungus spreads to other organs such as the lymph nodes, liver, spleen, skin, gastrointestinal tract, and bone marrow. This form is commonly seen in immunocompromised patients. Skin involvement is more common in the disseminated form, where there may be widespread erythematous, umbilicated, and crusted papules and nodules. Gastrointestinal involvement is common, and patients may report abdominal pain, diarrhea, nausea, anorexia, gastrointestinal bleeding, and melena. Severe weight loss, fever, anemia, and hepatosplenomegaly can result.

Chronic disseminated histoplasmosis commonly appears months after a patient has left an endemic area. Patients may present with oral or pharyngeal ulcerations or with adrenal insufficiency after adrenal infiltration.

Disseminated histoplasmosis may be complicated by central nervous system infection in 5%-10% of cases and can manifest as meningitis, endocarditis, or pericarditis.

Immunocompromised patients have a high risk of dissemination, particularly those with human immunodeficiency virus (HIV) or lymphoma. The severity of disease is often influenced by other predisposing factors such as corticosteroid use, diabetes, malignancy, and connective tissue disease. Infants and adults over 55 years of age are also at risk for disseminated disease.

Cutaneous:
Primary cutaneous histoplasmosis is rare and occurs after trauma to the skin with an infected instrument. Cutaneous histoplasmosis may present as a nodule or indurated ulcer with associated lymphadenopathy.

In general, people at higher risk of exposure to infected soils include spelunkers, construction workers, and agricultural workers. Risk factors for systemic histoplasmosis include many immunosuppressed states. Disseminated histoplasmosis is considered an AIDS-defining illness. Patients who have AIDS along with histoplasmosis usually present with weight loss and fever.

Codes

ICD10CM:
B39.9 – Histoplasmosis, unspecified

SNOMEDCT:
12962009 – Histoplasmosis

Look For

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

Because the skin lesions of histoplasmosis are nonspecific, the differential diagnosis can be challenging.

Pulmonary (acute): Disseminated (acute or chronic):
Cutaneous:

Best Tests

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Management Pearls

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Therapy

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Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

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References

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Last Reviewed: 10/04/2018
Last Updated: 10/05/2018
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Histoplasmosis
See also in: Oral Mucosal Lesion,Pulmonary
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Histoplasmosis (Pulmonary) : Chest pain, Cough, Fever, Mediastinal lymphadenopathy, Plaque with ulcer
Clinical image of Histoplasmosis
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