A Spectrum of Metastatic Disease in the Chest: Insights for the Radiologist

The diverse imaging manifestations of thoracic metastatic disease often challenge accurate interpretation. Malignant cells usually arrive via the bloodstream but find fertile substrates within the pulmonary circulation, lymphatic networks, branching airways, and pleural envelope. Unusual metastatic nodules cavitate, calcify, or hemorrhage. Widespread intravascular tumor may induce pulmonary hypertension. In lymphangitic carcinomatosis the deep and superficial lymphatic networks expand with tumorlets, with consequent parenchymal congestion. Nodal lymphomas can spread retrograde via lymphatic pathways, forming multilobar consolidations that mimic pneumonia. Sarcoid-like reactions occasionally develop in thoracic nodes and lung in settings of malignancy or immunotherapy, and are often confused with tumor recurrence.