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  • • Infection occurs after inhalation of spores with male:female ratio of 3:1

    • In lungs, fungus germinates into yeast; cause caseating necrosis and calcification

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Acute Infection

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  • • Several different presentations:

    • -Flu-like syndrome

      -Flu-like syndrome but limited to lungs

      -Diffuse nodular disease

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Chronic Infection

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  • • Several presentations:

    • -Asymptomatic solitary nodule < 3 cm with central calcifications in lower lobes (histoplasmoma)

      -In patients with chronic obstructive pulmonary disease, cavitary histoplasmosis 3

      -Mediastinal granulomas resulting in broncholithiasis, esophageal traction diverticula, superior vena cava (SVC) compression, transesophageal (TE) fistulas

      -Fibrosing mediastinitis with SVC, tracheal, or esophageal compression

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Epidemiology

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  • • Pulmonary fungal infections are rising due to widespread use of broad-spectrum antibiotics, immunosuppressive drugs, and HIV infection

    • Occur anywhere in world, some with characteristic endemic areas

    Histoplasma capsulatum is found in fowl and bat excreta, pigeon roosts, chicken houses, caves, hollow trees, attics and lofts

    • -Endemic to fertile river valleys, such as Mississippi, Missouri, and Ohio Rivers

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Symptoms and Signs

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  • • Immunocompetent patients, asymptomatic

    • Cough, malaise, hemoptysis, fever, weight loss (30% have coexistent TB)

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Acute Infection

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  • • Ranging from flu-like illness to diffuse nodular disease

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Chronic Infection

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  • • Variety of presentations:

    • -Histoplasmoma most common

      -Local mediastinal compression can occur

    • Disseminated disease (acute, subacute, and chronic form): Fever, abdominal pain, hepatosplenomegaly, pancytopenia

    • Solitary pulmonary nodules: 15-20% are from histoplasmosis

    • Constrictive pericarditis if pericardium involved

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Laboratory Findings

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  • • High or rising serum titers

    • Tissue cultures, sputum cultures

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Imaging Findings

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  • Chest film: Hilar adenopathy common, diffuse interstitial pneumonitis (25%)

    • In acute presentation, chest film ranges from upper lobe opacities to diffuse 3-4 mm nodules

    • Cavitation indicates advanced disease

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  • • High/rising serum titers (> 1:32 or elevated 4×)

    • Histoplasmin skin test (positive in 2-6 wks)

    • Sputum cultures positive in 10%, tissue cultures more reliable

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Rule Out

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  • • TB

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  • • Chest x-ray

    • Chest CT scan

    • Sputum microscopy and cultures

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  • • Medical therapy is indicated in immunocompromised hosts or in cavitary or severe disease

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Surgery

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  • • Operative therapy only for complications:

    • -Broncholithectomy + pulmonary resection

      -Repair of TE fistula

      -Decompression of mediastinal granulomas

      -Saphenous vein bypass for severe SVC compression

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Indications

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  • • Complications of histoplasmosis

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Medications

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  • • Ketoconazole/itraconazole (6 mos) for cavitary disease

    • Amphotericin B for more serious infections or in immunocompromised patients

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References

Piarrouz R et al: Assessment of preemptive treatment to prevent severe candidiasis in critically ill surgical patients. Crit Care Med 2004;32:2443.
Walsh TJ et al: Voriconazole compared with liposomal amphotericin B for empirical antifungal therapy in patients with neutropenia and persistent fever. NEJM...

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