PULMONARY HISTOPLASMOSIS

Histoplasmosis is a common infection in the central United States and is acquired through inhalation of airborne spores. The majority of inf ected persons have an asymptomatic, self-limiting illness. Clinical pn eumonia occurs in those with exposure to a large number of infecting s pores. Resolution of the pneumonia often leaves calcified pulmonary no dules, calcified mediastinal lymph nodes, or splenic calcifications. C hronic disease, which mimics tuberculosis, may develop in those with u nderlying emphysema. In patients with deficient cell-mediated immunity , Histoplasma capsulatum may disseminate throughout the body; this oft en is fatal. Delayed manifestations arise months or years after the pr imary infection. Broncholithiasis occurs when peribronchial calcific n odes produce bronchial obstruction. Mediastinal granuloma is the conti nued proliferation of fibrous tissue in draining mediastinal lymph nod es. These granulomas may obstruct adjacent veins, arteries, or airways and lead to various clinical symptoms.