Thrombophlebitis and vena cava syndromes
- Lesion
Clots in veins, with or without inflammation, most often in the deep veins of the legs. Tumours can also squeeze or clog the great veins.
What it is
Thrombophlebitis (thrombosis with inflammation) and phlebothrombosis (thrombosis without much inflammation) describe the same process. Deep leg veins account for most cases, driven by Virchow's triad: stasis (immobility, heart failure), endothelial injury and hypercoagulability (cancer, pregnancy, estrogen, inherited thrombophilia). Migratory thrombophlebitis (Trousseau sign) is a paraneoplastic hypercoagulable state. Superior vena cava syndrome is usually caused by tumours in the mediastinum; inferior vena cava syndrome by tumours invading or compressing the IVC or by thrombosis.
Structure
- Venous thrombus: soft, red, cast-like; lines of Zahn are less obvious than in arterial thrombi; attached at its point of origin.
- Thrombophlebitis: inflammatory cells in the vein wall around the thrombus.
Step by step
- Stasis, endothelial injury or hypercoagulability tilt hemostasis toward clotting in a vein.
- A red thrombus (rich in red cells and fibrin) forms, often behind a valve cusp.
- It propagates toward the heart; inflammation of the wall may make it painful.
- Fragments can break off and embolise to the lungs.
- Unresolved thrombi organise and destroy valves, leading to post-thrombotic syndrome.
Clinical notes
- Leg swelling, pain and warmth suggest deep vein thrombosis, but signs are unreliable; ultrasound confirms.
- Unexplained recurrent or migratory venous thrombosis in an older adult should prompt a search for cancer.
Test yourself
Think of the answer, then tap the question to see it.
What is Trousseau syndrome?
Migratory superficial thrombophlebitis caused by a cancer-associated hypercoagulable state, typically with pancreatic or other mucin-secreting adenocarcinomas.
Which tumours most often cause superior vena cava syndrome?
Lung carcinoma (especially small cell) and mediastinal lymphomas.
What is the most feared complication of deep vein thrombosis?
Pulmonary embolism.
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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Thrombophlebitis: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.