Superior Vena Cava Syndrome due to Thrombosis: A Rare Paraneoplastic Presentation of Bronchogenic Carcinoma.

Superior vena cava (SVC) syndrome is not an uncommon occurrence in patients with malignancy and it is often described as a medical emergency. In majority of the cases, SVC syndrome occurs due to mechanical obstruction of the SVC by extraluminal compression with primary intrathoracic malignancies. However, intraluminal obstruction due to thrombosis can also produce symptoms and signs of SVC syndrome. Clot-related SVC obstruction is mostly associated with indwelling central venous catheter and pacemaker leads, although such thrombosis can occur spontaneously in a background of a hypercoagulable state, e.g., malignancy. Here, an unusual case of sudden onset SVC syndrome has been reported, which on initial radiologic evaluation was found to have a lung nodule without any significant mediastinal mass or adenopathy compressing SVC. Subsequent investigation with Doppler ultrasonography of the neck showed thrombosis in the right internal jugular, right subclavian and right brachiocephalic vein, which was responsible for SVC syndrome. Histopathological evaluation of lung nodule confirmed presence of an adenocarcinoma. Therefore, venous thromboembolism as a paraneoplastic syndrome should be kept in mind while evaluating a case of SVC obstruction in a cancer patient. Management of the underlying disease is of prime importance in such cases and anticoagulation is the mainstay of therapy. Ability to identify paraneoplastic syndrome may have a significant effect on clinical outcome, ranging from early diagnosis to improved quality of life of the patient.