Pulmonary inflammatory pseudotumor is the most common primary lung mass seen in children, but extraparenchymal involvement is relatively rare. We report here on a case of inflammatory pseudotumor involving the mediastinum and the pulmonary artery. A 48-year-old man presented with enlargement of the right hilum on a simple chest radiograph. He had a history of exertional dyspnea for 1 year. A non-homogeneous enhancing mass was noted in the right pulmonary artery on computed tomography. Mediastinotomy and pulmonary artery angiography with a forcep biopsy revealed inflammatory pseudotumor of the mediastinum and pulmonary artery.