Hemoptysis is rare in histoplasmosis in the absence of chronic bronchitis or cavitary disease. If histoplasmosis is complicated by cavitary disease or chronic bronchitis, hemoptysis is common, with blood streaking being more common than frank hemoptysis. Significant hemoptysis should raise the suspicion of a superinfection with fungus such as Aspergillus fumigatus . Chronic histoplasmosis causes lung destruction leading to gradual development of respiratory insufficiency. Because of the high incidence of false negative results and the high prevalence of positive skin tests in endemic areas, the Histoplasmin skin test has limited diagnostic value.
Serologic tests are often falsely negative.
Histoplasma capsulatum polysaccharide antigen detection in urine and blood of AIDS patients with disseminated histoplasmosis is helpful in diagnosing and following the response to treatment. Its role in chronic pulmonary histoplasmosis has not been established. Pulmonary function tests are normal in one half of cases. The remaining patients have mild to moderate obstructive defects, and a few have severe obstructive defects. These reflect the underlying COPD, however, chronic pulmonary histoplasmosis is associated with further decline in spirometry.