Pulmonary artery occlusion due to histoplasmosis.

Histoplasma mediastinitis with complete or partial pulmonary artery obstruction due to compression and/or intraluminal granuloma was diagnosed in five patients and surgically verified in two. The patients, ages 12-27 years, had cough, dyspnea (four cases), and hemoptysis (two cases). Radionuclide imaging showed unilateral absence of pulmonary perfusion and minimal diminution of ventilation. Differentiation of this inflammatory process from other causes of ventilation-perfusion mismatch, for example, congenital hypoplasia and certain acquired causes of arterial obstruction, especially thromboembolism, may be possible by correlating radiographs, laminograms, and clinical history. Angiography can delineate the extent of perfusion impairment and may suggest its cause.