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USMLE
Disorders of the Respiratory System and Critical Care Illness
A 64-year-old man presents to the emergency department complaining of shortness of breath and facial swelling. He smokes one pack of cigarettes daily and has done so since the age of 16. On physical examination, he appears dyspneic at an angle of 45 degrees or less. His vital signs are as follows: heart rate 124 bpm, blood pressure 164/98 mmHg, respiratory rate 28 breaths/min, temperature 37.6°C (99.6°F), and oxygen saturation 89% on room air. Pulsus paradoxus is not present. His neck veins are dilated and do not collapse with inspiration. Collateral venous dilation is noted on the upper chest wall. There is facial edema and 1+ edema of the upper extremities bilaterally. Cyanosis is present. There is dullness to percussion and decreased breath sounds over the lower half of the right lung field. Given this clinical scenario, what would be the most likely finding on a CT examination of the chest?
Explanation
ExplanationThis clinical scenario describes an individual with superior vena cava (SVC) syndrome, which is an oncologic emergency. Eighty-five percent of cases of SVC syndrome is caused by either small-cell or squamous-cell cancer of the lung. Other causes of SVC syndrome include lymphoma, aortic aneurysm, thyromegaly, fibrosing mediastinitis, thrombosis, histoplasmosis, and Behcet syndrome. The typical clinical presentation is dyspnea, cough, and facial and neck swelling. Symptoms are worsened by lying fat or bending forward. As the swelling progresses, it can lead to glossal and laryngeal edema with symptoms of hoarseness and dysphagia. Other symptoms can include headaches, nasal congestion, pain, dizziness, and syncope. In rare cases, seizures can occur from cerebral edema, although this is more commonly associated with brain metastases. On physical examination, dilated neck veins with collateralization on the anterior chest wall are frequently seen. There is also facial and upper extremity edema associated with cyanosis. The diagnosis of SVC syndrome is a clinical diagnosis. A pleural effusion is seen in about 25% of cases, more commonly on the right. A chest CT would demonstrate decreased or absent contrast in the central veins with prominent collateral circulation and would help elucidate the cause. Most commonly, this would be mediastinal adenopathy or a large central tumor obstructing venous fow. The immediate treatment of SVC syndrome includes oxygen, elevation of the head of the bed, and administration of diuretics in combination with a low-sodium diet. Conservative treatment alone often provides adequate relief of symptoms and allows the determination of the underlying cause of the obstruction. In this case, this would include histologic confirmation of the cell type of the tumor to provide more definitive therapy. Radiation therapy is the most common treatment modality and can be used in an emergent situation if conservative treatment fails to provide relief to the patient.
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