<p>Fibrosing mediastinitis is a rare disease caused by benign proliferation of fibrous tissue within the mediastinum encircling the mediastinal organs, leading to compression of the surrounding bronchial and blood vessels. We report a case of fibrosing mediastinitis with rapidly progressive pulmonary vein stenosis evaluated using multimodality imaging. Computed tomographic pulmonary angiography demonstrated multiple pulmonary vein stenoses, while intravascular optical coherence tomography provided high-resolution characterization of the lesions, showing smooth vessel walls without evidence of thrombosis or significant intimal hyperplasia, suggesting an extrinsic compressive mechanism. These imaging findings complemented conventional angiography and influenced interventional strategy. This case highlights the incremental value of optical coherence tomography in assessing pulmonary vein stenosis associated with fibrosing mediastinitis.</p>