The Hypermetabolic Mushroom: Superior Vena Cava Syndrome

Presentation
A 40-year-old man, who had had a successful heart transplant, later developed a very rare and unrelated cardiac problem. He presented with progressive symptoms of cough along with cyanosis and swelling of the face and arms. On examination, he had edema of the face and upper torso and telangiectasias on his chest (Figure 1A). His jugular veins were nonpulsatile and distended. The patient had a history of heavy

Assessment
Cardiac ultrasound revealed what appeared to be a thrombus in the right atrium. A contrast-enhanced computed tomography (CT) scan of the chest demonstrated multiple venous collaterals (Figure 1B). More striking was a mediastinal mass measuring 5.1 in (130 mm) at its largest diameter; this protruded through the superior vena cava and entered the right atrium (Figures 1B and 1C). The mass, including the portion that extended into the vena cava, was mushroom-shaped and hypermetabolic on 18F-fluorodeoxyglucose positron emission tomography (Figure 1D).There were no other

Diagnosis
The patient presented with typical superior vena cava syndrome, marked by cyanosis and edema of the face, neck, arms, and upper chest. In addition, he had jugular turgor due to increased venous pressure engendered by obstruction of the superior vena cava. He had no headache or dyspnea, common symptoms thought to be secondary to cerebral and laryngeal edema. These were likely prevented by progressive blockage that spurred formation of collateral circulation.

Malignancy is the most common cause of this syndrome. Lung cancer, particularly masses located in the upper lobe of the right lung, can impede blood flow through the superior vena cava. The obstruction, which may or may not include a tumor-related thrombus within the vessel, can be the result of tumor invasion or external pressure by the mass or by nearby enlarged lymph nodes. Lymphoma, thymoma, thyroid, and other expansive processes in the mediastinum also can lead to superior vena cava syndrome, as can blood clots caused by invasive medical procedures, such as implantation of a pacemaker wire or placement of an intravenous central catheter. Rarely, infectious causes, including syphilis, tuberculosis, histoplasmosis, and actinomycosis, can trigger the instigating obstruction. Similarly, granulomatous diseases like sarcoidosis can occasionally produce superior vena cava syndrome.

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–Benjamin Coiffard, MD, Xavier Elharrar, MD, Thomas Vandemoortele, MD, Sophie Laroumagne, MD, Hervé Dutau, MD, Philippe Astoul, MD, PhD

This article originally appeared in the May 2014 issue of The American Journal of Medicine.