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Findings: CT scan of the chest demonstrated densely calcified mediastinal granuloma and a broncholith in the orifice of the right upper lobe bronchus. (Figs. 1 and 2). CT of the lung demonstrated constriction of the right middle lobe bronchi due to peribronchial fibrosis and right middle lobe collapse (Figs. 3 and 4).
Diagnosis: Mediastinal granuloma and broncholithiasis due to histoplasmosis.
Discussion: Histoplasmosis is a common infection in the central United States and is acquired through inhalation of air-borne spores. The majority of infected persons have an asymptomatic, self-limiting illness. H capsulatum is the pathogen which was discovered by Samuel Darling, M.D. in 1905. (1)
Histoplasmosis may cause mediastinal granuloma, diffuse mediastinal fibrosis, sclerosing mediastinitis and mediastinal collagenosis.(2) Mediastinal granuloma occurs more frequently than diffuse mediastinal fibrosis: It can encroach on and obliterate adjacent vasculatures and airway passages(3) causing obstructive atelectasis or pneumonia and vascular occlusion. Pathology: The mediastinal granuloma is comprised of enlarged lymph nodes surrounded by fibrous capsule.
Broncholithiasis is an uncommon condition that is a delayed complication of histoplasmosis. Both calcified peribronchial node and peribronchial inflammatory process may produce bronchial obstruction with clinical manifestations of pneumonia.
Chest CT scan accurately depict the broncholith and calcified lymph nodes and its obstructive airways or vasculatures.(4)
When patients with broncholithiasis from endemic regions of histoplasmosis, the differential diagnosis must include tuberculosis, cryptococcosis, actinomycosis and coccidiodomycosis.(5)
Bronchoscopy combined with CT of the chest can be 100% effective in making the diagnosis of broncholithiasis.(5)
The management of broncholithiasis include observation, removal of stones by means of rigid bronchoscopy and surgical intervention is indicated for recurrent massive bleeding, recurrent pneumonia, and fistula.(6,7)
References:
Darling ST. A Protozoan General Infection Producing
Pseudotubercles in the Lungs and Focal Necrosis in the Liver,
Spleen, and Lymph Nodes. JAMA 1906;46:1283-1285.
Gurney JW, Conces DJ. Pulmonary Histoplasmosis. Radiology 1996;199:297-306.
Goodwin RA, Nickell JA, DesPrez RM. Mediastinal Fibrosis Complicating
Healed Primary Histoplasmosis and Tuberculosis. Medicine 1972;51:227-246.
Conces DJ, Tarver RD, Vix VA. Broncholithiasis: CT Features in 15 Patients.
AJR 1991;157:249-253.
Dixon GF, Donnerberg RL, Schonfeld SA, Whitcomb ME. Advances in the Diagnosis
and Treatment of Broncholithiasis. Am Rev Respit Dis 1984;1028-1030.
Moersche HJ, Schmidt HW. Broncholithiasis. Am Oto Rhino Laryngeal
1959;68:548-563.
Faher LP, Jensek RJ, Chawla SK, Kittle CF. The Surgical Implications of Broncholithiasis.
J Thoracic Cardiovascular Surg 1975;70:779-789.
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