From the Guidelines
Disseminated histoplasmosis manifests as a systemic fungal infection with varied clinical presentations, including fever, weight loss, fatigue, respiratory symptoms, hepatosplenomegaly, lymphadenopathy, mucocutaneous lesions, and central nervous system involvement. The diagnosis typically requires identification of Histoplasma capsulatum through culture, histopathology, antigen detection, or serology 1.
Clinical Manifestations
- Fever
- Weight loss
- Fatigue
- Respiratory symptoms (cough, dyspnea)
- Hepatosplenomegaly
- Lymphadenopathy
- Mucocutaneous lesions
- Central nervous system involvement Treatment for severe disseminated disease usually begins with liposomal amphotericin B (3-5 mg/kg daily) for 1-2 weeks, followed by itraconazole (200 mg twice daily) for at least 12 months, as recommended by the Infectious Diseases Society of America 1.
Treatment Approach
- Liposomal amphotericin B for 1-2 weeks
- Itraconazole for at least 12 months Mild to moderate cases may be treated with itraconazole alone 1. Immunocompromised patients often require longer treatment courses and may need lifelong suppressive therapy with itraconazole (200 mg daily) 1.
Special Considerations
- Immunocompromised patients: longer treatment courses and potential lifelong suppressive therapy
- Monitoring: liver function, drug levels, and clinical response The infection spreads when spores from soil contaminated with bird or bat droppings are inhaled, with risk factors including immunosuppression, HIV/AIDS, and exposure in endemic regions like the Ohio and Mississippi River valleys 1. Regular monitoring of liver function, drug levels, and clinical response is essential during treatment 1.
From the Research
Manifestations of Disseminated Histoplasmosis
The manifestations of disseminated histoplasmosis can vary, but common symptoms include:
- Fever, which can be prolonged 2, 3
- Hepatosplenomegaly, which is the enlargement of the liver and spleen 2, 3
- Cytopenias, such as anemia and leukopenia 2, 3
- Pancytopenia, which is a reduction in the number of red and white blood cells, as well as platelets 3
- Pulmonary infiltrates and hypoxia in severe cases 4
- Granulomatous lymphadenitis with intracellular yeast-like elements, as seen in histopathological studies 2
- T cell deficiency, which can increase the risk of opportunistic infections 3
Clinical Presentations
Disseminated histoplasmosis can present in different ways, including:
- Acute pulmonary infection, which can cause fever, hypoxia, and pulmonary infiltrates in otherwise healthy hosts 4
- Chronic pulmonary histoplasmosis, which can occur in individuals with structural defects in the lung, such as emphysema 4
- Opportunistic histoplasmosis, which can develop in patients with cellular immune deficiency, such as those with AIDS or taking immunosuppressants 4
- Disseminated histoplasmosis, which can affect multiple organs, including the liver, spleen, and bone marrow 5, 2, 3
Diagnosis and Treatment
Diagnosis of disseminated histoplasmosis is typically made by visualization of yeast in tissue or by culture 4. Treatment options include:
- Amphotericin B, which is often used as first-line therapy for severe cases 5, 2, 3
- Itraconazole, which is used as second-line therapy or for step-down therapy following response to amphotericin B 5, 4, 6, 3
- Isavuconazole, which may be considered in cases where first-line and second-line therapies have failed or are contraindicated 5