Fibrosing Mediastinitis and Complete Right Pulmonary Artery Occlusion

A 53-year-old woman with chronic cough, exertional dyspnea, and progressive chest pain presented with tachycardia and low oxygen saturation (86% on room air).She had a history of gastroesophageal reflux disease, paint fume exposure, and pulmonary histoplasmosis.Cardiac evaluation was unremarkable, but chest radiography showed a prominent pulmonary artery silhouette and decreased vascularity in the right lung, suggesting pulmonary embolism.Pulmonary computed tomography (CT) angiography was performed using a dual-energy CT (DECT) system, and CT revealed a right hilar partially calcified soft-tissue lesion obliterating the right main pulmonary artery and total occlusion of the right main pulmonary artery.Additionally, CT iodine density map images demonstrate total perfusion defect in the right lung, no perfusion within the right hilar mass, and abrupt occlusion of the right pulmonary artery (Figure 1).Bronchoscopy and biopsy confirmed fibrosing mediastinitis with caseous necrosis and dystrophic calcification.The patient was started on oxygen supplementation and corticosteroids.At 1-year follow-up, her condition remained stable.Fibrosing mediastinitis involves fibroinflammatory encasement of mediastinal structures, frequently secondary to Histoplasma capsulatum.This case