Superior vena cava syndrome (SVCS) is usually caused by cancer. In adults, SVCS most commonly occurs with lung cancer or non-Hodgkin lymphoma. A tumor in the chest or swollen lymph nodes can press on the superior vena cava, blocking the blood flow. There are other less common causes for the superior vena cava to become blocked:
- A blood clot that forms as a side effect from the use of intravenous catheters (a flexible tube used to put fluids into or take blood out of a vein). A clot may also form as a side effect of pacemaker wires.
- Infection in the chest that causes affected tissues to become thick and hard.
- Other cancers, including metastatic breast cancer, metastatic germ cell tumors, colon cancer, esophageal cancer, Kaposi sarcoma, fibrous mesothelioma (cancer of the epithelium), and Hodgkin lymphoma.
- Bechet syndrome (a disease of the immune system).
- Tumors in the thymus or thyroid.
- Sarcoidosis (a disease of the lymph nodes that acts like tuberculosis).