Cardiac Pheochromocytoma Presenting as Shortness of Breath

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To the Editor:

Paragangliomas, commonly known as pheochromocytomas in the adrenal medulla, are among the rarest cardiac tumors, accounting for <1% of cardiac masses.¹ We report a case of an aortic root paraganglioma discovered after work-up for shortness of breath.

A 74-year-old woman with a history of hypertension, coronary artery disease, and breast cancer presented to her physician with progressive shortness of breath on exertion. Her blood pressure was well controlled on metoprolol, and her breast cancer was in remission after being treated 10 years prior with mastectomy and radiation therapy. Cardiac catheterization was performed to evaluate her known coronary disease and revealed severe stenosis in her left anterior descending artery and an unusual blushing network proximal to the aorta. The patient was referred to our hospital for further work-up. On physical examination, the patient was normotensive with normal vital signs. Her cardiac and physical examinations were unremarkable, with no evidence of lymphadenopathy. After a transthoracic echocardiography showed no significant pathology, a transesophageal echocardiography was performed. An echogenic mass measuring approximately 1.7×2.8 cm was noted between the left atrium and pulmonary artery (Figure, A). The mass was vascular, but no arterial-venous fistula was appreciated. Cardiac magnetic resonance imaging was performed for further characterization and revealed a well-circumscribed, soft, compressible mass fed mainly by an arterial vascular supply (Figure, B). Computed tomography of the chest, abdomen, and pelvis was performed to evaluate for metastases or other malignancies. Computed tomography confirmed the cardiac mass but no other tumors or adenopathy. These findings were suspicious for a primary cardiac tumor, but given the vascularity and location of the mass, percutaneous biopsy was not a viable option. Positron emission tomography was performed to determine the metabolic activity of the mass and whether open biopsy or complete resection, or both, were needed. The decision for complete resection and coronary artery bypass of the left anterior descending artery was made after positron emission tomography showed moderately intense fluorodeoxyglucose F-18 uptake within the mass, suspicious for a primary malignancy (Figure, C). Pathology revealed predominantly monomorphic cells with abundant granular cytoplasm arranged in characteristic Zellballen organoid pattern. Sustentacular cells were positive for S-100, CD31, and CD34, highlighting the rich vascular network. Tumor cells were positive for neuron-specific enolase, synaptophysin, and chromogranin. All these findings were consistent with paraganglioma.

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  Paracardiac mass located between the aorta (Ao), pulmonary artery (PA), and left atrium (LA). Transesophageal echocardiography (A) with transducer rotated to 85° demonstrates an echogenic mass (arrow). T2-weighted turbo spin echo cardiac magnetic resonance (B) demonstrates circumscribed mass, which is relatively hyperintense when compared with nearby muscle, suggestive of increased vascularity. Positron emission tomography with fluorodeoxyglucose F-18 (C) demonstrates moderately increased metabolic activity of the mass (arrow). RA=right atrium.

Cardiac paragangliomas are extremely rare extra-adrenal tumors originating from the primitive neural crest. Paragangliomas outside the adrenal medulla and aorticosympathetic ganglia are generally hormonally inactive,² making clinical diagnosis a challenge. Modern classification is based on histology, location, and innervations, and is divided into 4 groups: brachiomeric, intravagal, aortic-sympathetic, and visceral-autonomic.³ Aortic body paraganglioma, as present in our patient, is classified in the brachiomeric group, which usually has fewer metastases and better prognosis.⁴ Although these tumors are often chemically inert, they are highly vascular and can parasitize the coronary circulation.¹ The mainstay of therapy for these tumors is complete surgical resection. However, unlike adrenal pheochromocytomas, cardiac paragangliomas have a less defined capsule and tend to grow into adjacent structures, making resection difficult.¹ This case demonstrates the importance and strength of multimodality imaging in evaluating cardiac masses. Information from each imaging study added to the management of our patient's case, which ultimately led to a definitive diagnosis and potentially curative procedure.

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References 

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