Superior vena cava syndrome as unilateral right breast enlargement.

This case report describes a postmenopausal woman presenting to the breast surgery clinic with right breast enlargement, new spider veins on the chest, dyspnea, and facial swelling. She was treated for lung cancer. Imaging showed her right hilar mass causing critical superior vena cava (SVC) stenosis. She was transferred to thoracic surgery, underwent SVC stent placement, and her symptoms improved. SVC syndrome as a cause of right breast enlargement is unusual; therefore, carefully reviewing symptoms, medical history, and physical examination is crucial for diagnosis.