Metastatic disease may affect the thorax in a number of different ways, most commonly in the form of lung nodules, lymph node enlargement, pleural effusion, and osseous lesions. Much less commonly, extrathoracic malignancies may embolize to the lungs. Large vessel tumor emboli may be detected in thoracic imaging studies as pulmonary arterial filling defects or as "beaded"-appearing pulmonary vessels. Occasionally, tumor embolization may affect only the small pulmonary arteries and may induce fibrocellular intimal hyperplasia and produce thrombotic vascular occlusion, resulting in increased pulmonary vascular resistance and elevated pulmonary arterial pressure, potentially precipitating right ventricular failure: this condition is referred to as pulmonary tumor thrombotic microangiopathy. Patients with tumor thrombotic microangiopathy may present with worsening shortness of breath and progressive exercise intolerance, eventually manifesting features of right ventricular failure. The imaging features of tumor thrombotic microangiopathy are generally nonspecific, but thoracic computed tomography may show small nodular opacities with branching configurations resembling infectious bronchiolitis, or mosaic perfusion due to small vessel obstruction producing pulmonary perfusion derangements. Ventilation-perfusion scintigraphy will commonly show small, often nonsegmental, mismatched perfusion defects, and positron emission tomography may show hypermetabolism. The diagnosis of tumor thrombotic microangiopathy may be suspected in patients with known extrathoracic malignancy with persistent, progressive imaging abnormalities and unexplained dyspnea or hypoxemia, particularly when features of pulmonary hypertension are evident, although the diagnosis is rarely established before death.
- Cor pulmonale
- Right ventricular failure
- Thrombotic microangiopathy
- Tumor embolism
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine
- Critical Care and Intensive Care Medicine