Tree-in-bud sign as a manifestation of localized pulmonary lymphatic metastasis from a pancreas cancer.

The tree-in-bud appearance usually reflects benign disorders of the bronchovascular bundle. Pulmonary metastasis reportedly also shows a tree-in-bud pattern in cases of dilated peripheral pulmonary artery filled with intravascular tumor emboli or fibrocellular intimal hyperplasia of the small pulmonary arteries induced by tumor microemboli, or endobronchial metastatic disease. On X-ray CT, pulmonary metastases may result in four main types of imaging manifestations: nodules, lymphatic spread, tumor emboli, and endobronchial tumor, and show diffuse interstitial thickening or multiple nodules in general. We report a rare case of localized pulmonary peribronchovascular lymphatic tumor spread without intravascular tumor emboli from a pancreas cancer, which mimicked the localized vascular tree-in-bud sign.