Medical Care
Most acute forms of histoplasmosis in immunocompetent hosts resolve without specific treatment. Systemic antifungal treatment is indicated for severe acute pulmonary histoplasmosis, chronic pulmonary histoplasmosis (CPH), progressive disseminated histoplasmosis (PDH), and any manifestation in an immunocompromised patient. Specific therapy recommendations vary with the presenting syndrome.
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Syndromes in immunocompetent hosts
Localized disease: Antifungal therapy is unnecessary in patients with localized disease. However, oral itraconazole is recommended for 6-12 weeks in patients whose symptoms have not improved after 3-4 weeks of observation.
Severe acute pulmonary syndrome: Antifungal therapy (amphotericin B) is indicated for patients presenting with clinically significant dyspnea or hypoxemia. After discharge from the hospital, itraconazole should be used to complete a 12-week course of antifungal therapy. Patients with relatively mild manifestations can be treated with only itraconazole, and treatment should be continued for 3 months. Corticosteroids have also been used for short-term therapy (tapered over 2 wk); however, these agents always should be used with caution in fungal infections because of the risk of impaired cell-mediated immunity with prolonged use.
Mediastinal obstructive syndromes: For patients with clinically significant, symptomatic obstructive symptoms, antifungal treatment should be started. Reports describe successful treatment with oral (eg, itraconazole, ketoconazole) and systemic (amphotericin B) antifungal agents. Surgical resection should be considered for life-threatening obstruction or if a patient's condition fails to improve after 4-6 weeks of antifungal treatment. Surgical interventions do not prevent progression to fibrosing mediastinitis. Although reports mention successful surgical management of fibrosing mediastinitis, the surgical mortality rate is high, and surgeons inexperienced in managing this disorder should not attempt such interventions. Medical management with antifungal agents should be attempted first unless the obstruction is life threatening.
Pericarditis: Anti-inflammatory treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) or corticosteroids is the mainstay of management. Progression to constrictive pericarditis is described but rare.
Rheumatologic syndrome: Rheumatologic syndrome often resolves without treatment or with a brief course of NSAIDs.
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Syndromes in hosts with an underlying illness or immunodeficiency
CPH: Without antifungal treatment, CPH is progressive, causing loss of pulmonary function in most patients and death in up to half. Amphotericin B has been used most successfully and is effective in 59-100% of cases, but most patients can be treated with itraconazole or ketoconazole for at least 3 months. [5] Relapse rates are 10-15% with the last 2 agents; fluconazole is less effective. The preferred treatment is amphotericin B followed by itraconazole for 12-24 months.
PDH
Amphotericin B substantially reduces the mortality rate of PDH. A cumulative dosage of at least 35 mg/kg should be administered to prevent relapse. Liposomal preparations may be substituted to reduce toxicity but may have poor renal penetration.
Many patients have been treated successfully with a change to oral agents after their symptoms initially improve with amphotericin B. Itraconazole is the preferred oral agent, with a 6-month to 18-month course of treatment. Patients who cannot tolerate itraconazole should use fluconazole. After an initial 12-week intensive phase with amphotericin B to induce a remission, patients with AIDS require chronic life-long maintenance therapy to prevent relapse. Amphotericin B once or twice a week is effective but inconvenient and not well tolerated.
Azoles are highly effective in most cases, but relapse may occur. Treatment with fluconazole is discouraged because of its reduced efficacy as long-term maintenance therapy for histoplasmosis. Echinocandins should not be used.
Local manifestations of disseminated disease: Endocarditis is very difficult to treat and may require resection of the affected valve and systemic antifungal treatment.
Surgical Care
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Surgical consultation is indicated for patients with infections complicated by fistulas, hemoptysis, or broncholithiasis. The surgical management of mediastinal obstructive syndromes is somewhat controversial because they may improve with observation or medical therapy. Severe obstruction of the airways or large blood vessels may be life threatening, and immediate intervention may be required.
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In general, unroofing and debridement of large granulomas is preferable to excision. Fibrosing mediastinitis is especially difficult to manage because normal structures are encased in collagenous connective tissue. Surgeons in endemic areas often are well versed in the management of these surgically challenging problems.
Consultations
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Infectious disease specialists can assist in the differential diagnosis, in planning appropriate workup, and in choosing therapeutic regimens, particularly for immunocompromised patients.
Activity
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Bed rest has been recommended for systemic syndromes.
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Hilar lymphadenopathy in an 11-year-old child.
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Map demonstrates the distribution of histoplasmin skin-test positivity by region. Used with permission from the American Thoracic Society.
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Hematoxylin and eosin stain of infected lung tissue. Histoplasma organisms appear to have a false capsule.
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Starling roost in Alabama.
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Acute pulmonary syndrome in a 16-year-old female adolescent.
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Fibrosing mediastinitis with mediastinal widening and tracheal deviation.
