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Pathology - Pulmonary thromboembolism
Definition: Occlusion of a pulmonary artery by an embolic thrombus.
Epidemiology: Highly prevalent and frequently underdiagnosed.
Aetiology • Pulmonary emboli arise from deep vein thromboses, thus sharing identical risk factors, including immobility, acute medical conditions, recent surgical procedures, malignancy, pregnancy, and both inherited and acquired thrombotic diseases.
Pathogenesis: A piece of a detached thrombus from deep vein thrombosis embolizes via the right side of the heart into the pulmonary arterial circulation and becomes lodged in a pulmonary artery.
The clinical presentation is contingent upon the size of the pulmonary artery obstructed by the embolus. • Blockage of a large pulmonary artery usually leads to rapid death due to a sudden massive rise in pulmonary arterial pressure, acute right ventricular failure, and cardiac arrest. • Occlusion of medium-sized arteries results in a region of ventilation-perfusion imbalance in the lungs, leading to dyspnea. • Minor pulmonary emboli may produce mild manifestations of dyspnea, thoracic discomfort, and vertigo; these symptoms can often remain undetected.
Macroscopy
• Emboli appear as thrombi pieces within pulmonary arteries. • Thrombi are solid and brown, with the sliced surface potentially displaying discernible bands (lines of Zahn). Histopathology: Fresh thromboemboli consist of a composite of fibrin and interwoven blood cells, frequently organized in alternating linear bands that align with the macroscopic lines of Zahn. • Thromboemboli undergo organization after 2–3 days, characterized by the proliferation of granulation tissue consisting of fibroblasts and capillaries derived from the vessel wall. • Aged thromboemboli may manifest as fibrous nodules protruding from the vessel wall or as fibrous bands traversing the lumen of a pulmonary artery.
Prognosis
• Approximately 30% of all patients succumb to pulmonary embolism. • The mortalityz risk significantly increases if the diagnosis is not promptly established.
Definition: Occlusion of a pulmonary artery by an embolic thrombus.
Epidemiology: Highly prevalent and frequently underdiagnosed.
Aetiology • Pulmonary emboli arise from deep vein thromboses, thus sharing identical risk factors, including immobility, acute medical conditions, recent surgical procedures, malignancy, pregnancy, and both inherited and acquired thrombotic diseases.
Pathogenesis: A piece of a detached thrombus from deep vein thrombosis embolizes via the right side of the heart into the pulmonary arterial circulation and becomes lodged in a pulmonary artery.
The clinical presentation is contingent upon the size of the pulmonary artery obstructed by the embolus. • Blockage of a large pulmonary artery usually leads to rapid death due to a sudden massive rise in pulmonary arterial pressure, acute right ventricular failure, and cardiac arrest. • Occlusion of medium-sized arteries results in a region of ventilation-perfusion imbalance in the lungs, leading to dyspnea. • Minor pulmonary emboli may produce mild manifestations of dyspnea, thoracic discomfort, and vertigo; these symptoms can often remain undetected.
Macroscopy
• Emboli appear as thrombi pieces within pulmonary arteries. • Thrombi are solid and brown, with the sliced surface potentially displaying discernible bands (lines of Zahn). Histopathology: Fresh thromboemboli consist of a composite of fibrin and interwoven blood cells, frequently organized in alternating linear bands that align with the macroscopic lines of Zahn. • Thromboemboli undergo organization after 2–3 days, characterized by the proliferation of granulation tissue consisting of fibroblasts and capillaries derived from the vessel wall. • Aged thromboemboli may manifest as fibrous nodules protruding from the vessel wall or as fibrous bands traversing the lumen of a pulmonary artery.
Prognosis
• Approximately 30% of all patients succumb to pulmonary embolism. • The mortalityz risk significantly increases if the diagnosis is not promptly established.
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