A 70 year old male presentes with breathlessness, facial swelling and dilated veins on the chest wall. The MOST common cause is:

Breathlessness, facial swelling and dilated veins on the chest wall, are features of Superior vena caval obstruction. Lung cancer, paicularly of small cell and squamous cell histologies, accounts for approximately 85% of all cases of malignant origin. In young adults, malignant lymphoma is a leading cause of SVCS. When SVCS is noted in a young man with a mediastinal mass, the differential diagnosis is lymphoma vs primary mediastinal germ cell tumor. Ref: Harrisons principles of internal medicine, 18th edition, Page: 2266