Vascular sequelae of mediastinal fibrosis

摘要

Abstract Fibrosing mediastinitis is a condition in which mediastinal fat is replaced by fibrous tissue. Complications may arise due to progressive fibrotic infiltration and compression of major vascular, respiratory, and nervous structures within the mediastinum. We describe 3 similar cases of fibrosing mediastinitis with pulmonary vessel involvement. Imaging and intrao-perative observation revealed involvement of the pulmonary vasculature in all 3 patients. Perfusion studies showed decreased or absent perfusion to one or both of the lungs. All patients tested negative for histoplasmosis, 2 required lung resection, with the 3rd forgoing surgery. Fibrosing mediastinitis (FM) is a rare condition in which mediastinal fat is gradually replaced by fibrous tissue. Significant complications can occur secondary to progressive infiltration and compression of the major vascular, respiratory, and nervous structures within the mediastinum. A large majority of cases in the United States are associated with histoplasmosis infection,1 but it should be noted that < 1 % of histoplasmosis cases result in FM. This dimorphic fungus is endemic to certain regions of the United States, including Kentucky and the southeastern region.2 Although the exact pathophysiologic mechanism is unknown, the damage is believed to be due to antigen-mediated fibrosis. Granulomas burst into the mediastinum, leading to antigen-mediated inflammation and infiltrative fibrosis.3 Contrast-enhanced computed tomography (CT) is typically used to evaluate the extent of mediastinal involvement, with further workup dependent upon the structures involved.4 In the following 3 consecutive cases of complicated FM evaluated during a one-year period at the University of Kentucky, ventilation-per-fusion (V/Q) scans were utilized to assess lung involvement.