Abstract
Superior vena cava (SVC) syndrome is most often caused by malignant compression or thrombus formation and typically presents with progressive symptoms over weeks to months, while even acute cases usually evolve over several hours to days. We report a rare case of hyperacute SVC obstruction in a 53-year-old man with recurrent tongue carcinoma, a Hickman line in situ, and therapeutic anticoagulation for a recent pulmonary embolism. He developed profound cyanosis, facial and upper body swelling, and transient loss of consciousness within less than an hour. Imaging revealed a central line-associated thrombus causing complete SVC occlusion, and multidisciplinary input was required to balance the risks of catheter removal versus retention. This case underscores the importance of rapid recognition and coordinated management of SVC syndrome in high-risk oncology patients with central venous access.