Biopsy of the lung mass to obtain a histologic diagnosis is indicated. This patient has superior vena cava (SVC) syndrome, which is caused by inhibition of blood flow through the SVC or one of its major tributaries. The syndrome may occur in patients with both malignant and nonmalignant conditions. Cancers more commonly associated with SVC syndrome include lung cancer (both small cell and non–small cell lung cancer accounting for 65% of cases), aggressive lymphoma, thymoma, and primary mediastinal germ cell tumors. Nonmalignant causes include thrombosis and fibrosing mediastinitis. Presenting symptoms typically develop over weeks and include dyspnea, facial swelling, headache, and in more severe cases, stridor or mental status changes. The most common radiographic findings include mediastinal widening and pleural effusion; however, 16% of patients have a normal chest radiograph. Although in the past emphasis was placed on immediate treatment, current management emphasizes the importance of obtaining a histologic diagnosis, whenever possible, in patients with apparent malignant SVC syndrome. This allows for accurate decision-making regarding treatment of the underlying malignancy. Mediastinoscopy is routinely used to obtain tissue biopsy samples for histologic diagnosis. The complication rate from this procedure is only 5% in patients with SVC syndrome. Percutaneous transthoracic CT-guided needle biopsy appears to be a safe alternative to mediastinoscopy and has a sensitivity of 75%.

Although the patient clearly has SVC syndrome, he does not have stridor, laryngeal edema, or mental status decline. Immediate radiation therapy or stent placement is therefore not indicated.

Venography to identify a possible thrombosis is not indicated because the SVC syndrome in this patient is caused by external compression from a mediastinal mass and lymphadenopathy rather than by a thrombotic disorder.