Ann Thorac Surg 1996;61:1261-1262
© 1996 The Society of Thoracic Surgeons
Case Report
Pulmonary Venous Aneurysm Presenting as a Middle Mediastinal Mass
David A. DeBoer, MD,
Mitchell L. Margolis, MD,
Douglas Livornese, MD,
Karen A. Bell, MD,
Virginia A. Livolsi, MD,
Joseph E. Bavaria, MD
Departments of Cardiothoracic Surgery and Pathology, Hospital of the University of Pennsylvania, and Pulmonary Division, Department of Medicine, Philadelphia Veterans Affairs Medical Center, Philadelphia, Pennsylvania
Accepted for publication October 2, 1995.
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Abstract
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A large mediastinal mass in a 43-year-old man was proven at thoracotomy to comprise a right superior pulmonary vein aneurysm. Intraoperative transesophageal echocardiography was useful in defining the abnormality. Pulmonary venous aneurysm appears to represent an extremely rare but surgically correctable addition to the differential diagnosis of middle mediastinal masses.
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Introduction
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Although almost 10% of mediastinal masses in adults are of vascular origin, the majority of these are aneurysms of the aorta and its branches [1]. Abnormalities of the pulmonary venous system that give rise to a middle or superior mediastinal density are distinctly unusual, but include partial or total anomalous venous connections, pulmonary venous varicies, and a prominent venous confluence [1, 2]. We report a highly unusual case in which a large middle mediastinal mass resulted from an aneurysm of the right superior pulmonary vein, emphasizing the importance of intraoperative transesophageal echocardiography (TEE) in delineating the abnormality.
In May 1991 routine chest roentgenography disclosed a mediastinal mass in a 43-year-old man. Computed tomography demonstrated a large right-sided mass with equivocal contrast enhancement. The patient was asymptomatic and refused further investigation.
In July 1994, paroxysmal nocturnal dyspnea, palpitations, and orthopnea developed. The patient denied dyspnea on exertion or hemoptysis. There was no history of congenital heart disease, systemic vasculitis, tuberculosis, syphilis, or chest wall trauma. On physical examination, the lungs were clear and there were no cardiac murmurs. No clubbing, cyanosis, or edema was detected.
The chest radiograph demonstrated a large density enveloping the right hilum along the border of the proximal thoracic aorta (Fig 1
). A repeat computed tomographic scan of the chest revealed a large homogeneous mass adjacent to the ascending aorta and superior vena cava, anterior to the right main bronchus. A contrast injection was again inconclusive. The computed tomographic findings were unchanged from the previous study. Pulmonary arteriography was not performed. Pulmonary function tests were within normal limits.
The patient underwent right video thoracoscopy with attempted biopsy of the mediastinal mass. Upon inspection, the mass appeared pulsatile, and fine needle aspiration retrieved frank blood. At this point thoracoscopy was terminated and reoperation planned with cardiopulmonary bypass capabilities available.
Two days later, the patient underwent an exploratory posterolateral thoracotomy with intraoperative TEE. The TEE demonstrated a 6 x 5-cm aneurysmal dilatation of the right superior pulmonary vein with flow into the left atrium (Fig 2). The aneurysm was adjacent to, but distinct from, the right main pulmonary artery bifurcation. When the right hemithorax was entered, a large pulsatile mass appeared to arise from the right superior pulmonary vein or left atrium. Proximal control of the right main pulmonary artery was assured, with ensuing dissection and control of the superior and inferior pulmonary veins. A clamp was applied to the right main pulmonary artery. The aneurysm failed to decompress, excluding a pulmonary artery aneurysm or significant arteriovenous connection. A very proximal left atrial clamp was then added, and pulsation of the aneurysm ceased. Segmental pulmonary veins from the right upper lobe entered the aneurysm separately and were adherent to underlying parenchyma; hence a right upper lobectomy was performed along with excision of the superior pulmonary venous system. Recovery was uneventful, and the patient remains well 6 months after operation with complete remission of his presenting symptoms.
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Fig 2. . Transesophageal echocardiogram showing hypoechoic area distinct from right pulmonary arterial circulation.
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Gross pathologic examination revealed a 5.5 x 3.5 x 1.2-cm aneurysm with a contiguous tortuous vein that entered the right upper lobe parenchyma. Elastic stains showed focal interruptions in the elastic lamina and areas where the elastic lamina was completely absent. The segment of pulmonary vein within the pulmonary parenchyma was unremarkable. The margins of the resected aneurysm contained no atrial cardiac muscle, suggesting that the aneurysm was completely within the pulmonary vein and did not involve the left atrium.
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Comment
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The vascular nature of a mediastinal lesion is usually demonstrable on a computed tomographic scan with a well-timed contrast injection; yet the correct diagnosis in our case proved elusive despite two such studies. However, intraoperative TEE clearly demonstrated the vascular nature of the lesion and its anatomic relationship to the left atrium and pulmonary arterial tree. Thus our case underscores the usefulness of TEE in diagnosis and intraoperative decision-making when a mediastinal vascular abnormality is suspected.
It is unclear whether our patient's aneurysm was congenital or acquired. No antecedent trauma, infection, or vascular insult could be identified. The patient could recall no chest roentgenogram before 1991, and pathologic studies of the resected aneurysm could not establish its age. Embryologically the pulmonary veins arise from an outpouching of the sinoatrial region of the heart, which connects with that portion of the splanchnic plexus draining the lungs [2]. Eventually a common pulmonary vein is incorporated into the left atrial wall, leaving four independent veins to directly enter the left atrium. Conceivably a small developmental error produced a weak area in the wall of the right superior pulmonary vein. Because aneurysms are inherently unstable, enlarging as dilatation increases wall tension according to Laplace's law, a slow increase in size could ensue [3]. Thus, although our patient was asymptomatic in 1991, slight further enlargement of the lesion may have caused symptoms in 1994. In any event, symptoms were completely relieved after the operation.
In conclusion, pulmonary venous aneurysm is a rare, surgically correctable cause for a middle mediastinal mass. Diagnosis is aided by intraoperative TEE. Although the natural history remains uncertain, resection may relieve symptoms and prevent potentially lethal rupture.
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Acknowledgments
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We thank Ms Shirley Bethea for expert secretarial assistance.
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Footnotes
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Address reprint requests to Dr Bavaria, Department of Thoracic Surgery, Hospital of the University of Pennsylvania, 3400 Spruce St, Philadelphia, PA 19104.
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References
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- Kelly MJ, Mannes EJ, Ravin CE. Mediastinal masses of vascular origin. J Thorac Cardiovasc Surg 1978;76:559–72.[Abstract]
- Fraser RG, Pare JAP, Pare PD, et al. Diagnosis of diseases of the chest. Third Ed. Philadelphia: Saunders, 1991;1:96, 152–3, 742–8.
- Bartter T, Irwin RS, Nash G. Aneurysms of the pulmonary arteries. Chest 1988;94:1065–75.[Free Full Text]
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