Paracardiac Nonfunctioning Paraganglioma in a Young Woman
Paraganglioma, also referred to as pheochromocytoma when functionally active, is a rare tumor thought to arise from the neuroectodermally derived paraganglionic cells that are dispersed widely along the autonomic ganglia. Mediastinal localization is very rare and the clinical presentation is variable. In most cases, hypertension due to catecholamine excess is the main clinical manifestation; however, the majority of these tumors are asymptomatic.
A 36-year-old woman presented to her general practitioner with wheezing and dyspnea on exercise. Asthma was diagnosed, and she was treated with inhaled administration of a corticosteroid and a β2-agonist. Chest x-ray revealed a well-circumscribed, rounded mass at the level of the pulmonary artery (Figure 1), and the patient was referred to our institution for further evaluation. Her physical examination was unremarkable, and laboratory test results were essentially normal without elevation of serum tumor markers. Determinations of norepinephrine and normetanephrine levels were normal. Magnetic resonance imaging showed a hypervascularized mass in the middle mediastinum that extended from the anterior wall of the left atrium to the aortopulmonary window (Figure 2). Positron emission tomography revealed a focal increase in [18F]fluorodeoxyglucose uptake in the mediastinum. Because of the close proximity of this mass to the heart, a coronary angiography was performed (Figure 3), which revealed a highly vascularized mass receiving branches from the proximal left anterior descending and circumflex arteries. In the differential diagnosis of the mass, we considered teratoma (on the basis of the mass location and the patient’s clinical profile), sarcoma (owing to the vascular nature of the tumor), and paraganglioma (which are highly vascularized tumors, many of which do not secrete catecholamines). Surgical removal of the mediastinal tumor was performed. The pericardium was opened anteriorly to allow adequate exposure of the intrapericardial mass; the mass was located beside the main pulmonary artery and extending toward the left atrial appendage, but it did not infiltrate these structures. The tumor was completely removed (Figure 4).
In hematoxylin-eosin-stained sections (Figure 5A), an organoid structure was revealed; a nest of cells separated by connective tissue was observed. The S-100 stain showed sustentacular cells (dying, in brown) typical of paragangliomas (Figure 5B).