Ann Thorac Surg 2000;69:1926-1927
© 2000 The Society of Thoracic Surgeons
Case reports
Pericardial mesothelioma: the diagnostic dilemma of misleading imaging
David W. Quinn, FRCSa,
Ford Qureshi, FRCSa,
Ian M. Mitchell, FRCSa
a Department of Cardiothoracic Surgery, Nottingham City Hospital, Nottingham, United Kingdom
Address reprint requests to Dr Quinn, Office of Cardiopulmonary Transplantation, Department of Cardiothoracic Surgery, Queen Elizabeth Medical Centre, Edgbaston, Birmingham, UK B15, 2TH
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Abstract
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A young man with a short history of increasing dyspnea, cough, and ascites was initially diagnosed as having idiopathic constrictive pericarditis and referred for an operation. The procedure revealed an atypical invasive encapsulating disease. Complete resection was impossible, and only partial relief of constriction was achieved. The patient died shortly after. Histology revealed primary mesothelioma of the pericardium. The case illustrates the difficulty in establishing this diagnosis by echocardiography and computed tomography.
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Introduction
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Primary pericardial tumors are rare. Most appear during the third or fourth decade of life and are associated with a history of pericarditis, pericardial constriction, or tamponading hemopericardium. Surgery is the mainstay of treatment, but resection is often incomplete because of the extent of the tumor. The overall prognosis is poor.
A 36-year-old man presented with a three-month history of general malaise, increasing dyspnea on exertion, productive cough, weight gain, and distension of the abdomen. He had worked in sewage and power plants and as a mechanical fitter in a coal mine. He gave no history of childhood or occupational exposure to asbestos.
On examination the patient was in sinus rhythm with blood pressure of 90/50 mm Hg, elevated jugular venous pressure, prominent third heart sound, bilateral inspiratory crepitations, distended abdomen, and mild pitting edema of his ankles. While he was being admitted, ascites and edema worsened. At the referring hospital he had collapsed with a presumed vasovagal episode but had fully recovered by the time of the examination. Chest roentgenogram showed small bilateral pleural effusions and an enlarged, globular cardiac silhouette. Serial electrocardiography confirmed sinus rhythm and demonstrated transiently elevated ST-segments. An abdominal ultrasound scan revealed ascites and congestion of the liver. A tap of ascitic fluid confirmed the presence of a transudate. Computed tomography demonstrated a thickened pericardium associated with a small but well-defined pericardial effusion (Fig 1). Transthoracic echocardiography seemed to confirm those findings and also showed an unusually hypokinetic myocardium. The patient was referred for an urgent surgical procedure to obtain appropriate biopsy material and to relieve the constriction.
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Fig 1. Computed tomographic scan demonstrating thickened pericardium associated with a small but well-defined pericardial effusion (arrows).
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At operation the heart was found to be encased in a 2-cm thick pericardium with the appearance and consistency of coconut rind. Despite the findings on computed tomography, no pericardial fluid was evident; the pericardium was in fact densely adherent to the epicardium with no plane of separation between the two. Part of the anterior wall of the pericardium was removed with difficulty using cutting diathermy and sharp dissection. Twice during the operation, the heart went into ventricular fibrillation, requiring massage and defibrillation. After each episode cardiac function deteriorated. The operation was abandoned because of high clinical suspicion of a neoplastic process, the extensive encompassing nature of the pericardial disease, risk of coronary artery damage, and likelihood of further episodes of ventricular fibrillation. Samples of the myocardium and pericardium were sent for immediate histologic examination. The patient left the operating theater on an inotropic dose of dopamine. His central venous pressure had fallen during the procedure from 30 to 25 cm mm Hg, and his condition continued to deteriorate afterwards. Eighteen hours later electromechanical dissociation developed from which he could not be resuscitated.
Postmortem examination showed the heart to be completely encased by dense, white adherent tissue (see Fig 2) that extended along the ascending aorta, under the aortic arch, and along the pulmonary artery, stopping at the bifurcation. There was no evidence of distant metastasis. The lungs and liver were edematous and the abdomen contained 2 L of fluid.
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Fig 2. Pathologic specimen of heart with the right ventricular anterior wall incised (M = myocardium; T = tumor).
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Histopathologic examination revealed biphasic malignant mesothelioma; both epithelial and sarcomatous elements had invaded the epicardium. Results from pancytokeratin immunostain and tests for putative mesothelioma markers cytokeratin 5/6 and thrombomodulin were strongly positive. Electron microscopic examination of the tumor demonstrated well-developed cell junctions and villous processes consistent with the diagnosis of mesothelioma.
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Comment
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Pericardial mesothelioma presents either as a localized tumor associated with pericardial effusions [1] or as an encasing mass involving the whole pericardium [2]. The degree of invasion varies; local infiltration into the cardiac chambers is reported only occasionally [3] and distant metastasis even more rarely. The etiology is unknown, although other extrapleural mesotheliomas have been linked to therapeutic radiation [4]. The insidious onset of pericardial mesotheliomas may mimic that of benign pericardial constriction [5], and the past medical and occupational history may contain little to alert the surgeon to the diagnosis.
When a pericardial effusion is present, pericardiocentesis can temporarily improve symptoms but often fails to provide cytologic diagnosis [6]. In this case imaging studies (echocardiography and computed tomography) were misleading, because they suggested the presence of an abnormal amount of pericardial fluid and a surgical plane for resection. The imaging findings coupled with the urgency of the presentation prompted the decision to operate without further investigation. But as operative and pathologic findings revealed, the low-density echogenic region surrounding the heart was tumor rather than fluid. A previous case report of mesothelioma described similar misinformation from transthoracic echocardiography [2]. Magnetic resonance scanning is emerging as the best modality for demonstrating the extent and nature of the constrictive process [2, 7]. Figure 2 shows that endomyocardial biopsy would not have been helpful because invasion was confined to the epicardium. Although transcutaneous biopsy had been considered, in the face of available imaging data it would not have altered the decision to operate. Surgery was the only reasonable therapeutic strategy [8], given that radiotherapy or chemotherapy would have been purely palliative [2, 8]. Obtaining an intraoperative frozen section would not have altered the decision to abandon further dissection once the nature of the disease was apparent.
A primary difficulty in managing patients with this rare cancer is suspecting the diagnosis. Imaging, as long as it is accurate, is more important than cytologic diagnosis, which is often unreliable. Imaging studies can aid the surgeon in deciding if the tumor is localized and amenable to resection or if it is encapsulating, in which case resection is inappropriate. Unfortunately patients with encasing mesothelioma usually present late in the course of disease, when therapeutic options are limited and overall prognosis is poor.
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References
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Accepted for publication October 14, 1999.
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Abstract
Introduction
