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How to handle progressive disseminated histoplasmosis: bronchoscopy often helps narrow the differential diagnosis.

Article Excerpt
ABSTRACT: Progressive disseminated histoplasmosis (PDH) is most likely to occur in patients with AIDS. Typical signs and symptoms include fever, night sweats, anorexia, malaise, dyspnea, weight loss, hepatosplenomegaly, lymphadenopathy, skin lesions, and neurological deficits. The diagnosis of histoplasmosis can be confirmed by tissue culture and stains and by serological studies. Bronchoscopy with bronchoalveolar lavage (BAL) often plays a pivotal role in the workup, particularly in patients with respiratory symptoms and abnormal chest radiographic findings. In some cases, transbronchial biopsy in conjunction with BAL can improve the diagnostic yield. Liposomal amphotericin B or amphotericin B lipid complex is recommended for the initial treatment of moderately severe to severe PDH. Itraconazole may be appropriate for those with mild to moderate PDH and is recommended for maintenance therapy.

KEY WORDS: Histoplasmosis, Endemic mycoses, HIV/AIDS

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Histoplasmosis involving the lung is a common fungal infection in both immunocompetent and immunosuppressed persons. It may present as primary pulmonary histoplasmosis, in which the severity of illness depends largely on inoculum size; chronic cavitary histoplasmosis, which is associated with abnormal lung structure; or progressive disseminatedhistoplasmosis(PDH), which may present in a chronic, indolent fashion or as a fulminating, life-threatening illness. In HIV-infected patients who have low CD4 counts, histoplasmosis most often presents as PDH; however, the presentation of, as well as the diagnostic and treatment options for, PDH is different in HIV-infected patients than in immunocompetent patients.

In this article, we review the presentation, diagnosis, and treatment of PDH in patients who are infected with HIV.

PATHOGENESIS

Samuel Darling first described histoplasmosis in 1905 in a Panama Canal Zone worker. The etiological agent of histoplasmosis is Histoplasma capsulatum, a dimorphic fungus found in soil. This fungus is endemic in the river valleys of southern and central United States. Growth of H capsulatum is favored by moderate humidity, certain types of soil, and the excrement of bats and birds. (1)

When soil containing H capsulatum is disturbed, spores are inhaled and convert to the yeast phase in the alveoli. A neutrophilic tissue response occurs...

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