A 34-year-old woman with bilateral pulmonary infiltrates was diagnosed with sarcoidosis. She refused corticosteroid treatment despite a worsening of the pulmonary infiltrate, and thereafter developed dyspnea following hemoptysis 6 years later. The upper lobe branches of the pulmonary artery were obstructed and the left main pulmonary artery was narrowed by mediastinal soft tissue, thus complications of granulomatous mediastinitis and fibrosing mediastinitis were suspected. The mediastinal soft tissue regressed, following the administration of corticosteroids, whereas the vascular obstruction and narrowing remained unchanged. Although the obstruction or stenosis of major pulmonary vessels is rare in sarcoidosis, such potential developments should be considered when mediastinal soft tissue appears in follow-up examinations.