Ann Thorac Surg 2000;69:1571-1573
© 2000 The Society of Thoracic Surgeons
Case reports
Impersonation of a ruptured thoracic aneurysm by a transdiaphragmatic pancreatic cyst
Evgenij V. Potapov, MDa,
Matthias Bauer, MDa,
Friedrich Knollmann, MDa,
Henning Weidemann, MD, PhDb,
Peter Neuhaus, MD, PhDb,
Roland Hetzer, MD, PhDa
a Deutsches Herzzentrum Berlin, Berlin, Germany
b Universitätsklinikum Charité der Humboldt Universität zu Berlin, Campus Virchow-Klinikum, Berlin, Germany
Address reprint requests to Dr Potapov, Deutsches Herzzentrum Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
e-mail: potapov{at}dhzb.de
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Abstract
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Pancreatic cysts can, in rare cases, expand into the posterior mediastinum and may require surgical resection. We present the case of a patient with a thoracic aneurysm, in whom the mediastinal involvement of a chronic pancreatic cyst masqueraded as a ruptured aneurysm. Surgery was undertaken: first, the initial resection and drainage of the thoracic portion of the pseudocyst, and second, a thorough cleansing of the entire cyst through median laparotomy 15 days later.
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Introduction
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Pancreatic pseudocysts constitute a well-known complication of chronic pancreatitis with an incidence rate of 2% to 10%. They often develop either completely in the pancreas or expand intraabdominally along paths of least resistance into the peritoneum or bursa omentalis along the mesenteric vessels [1, 2]. The pleural fistula and extension into the posterior mediastinum with attendant pericardium have been described [2–5]. We report the case of a patient with a known thoracic aneurysm who manifested acute symptoms, and in whom a transdiaphragmatic pancreatic pseudocyst was mistakenly diagnosed as a ruptured aneurysm.
A 68-year-old man with a history of chronically recurrent pancreatitis was admitted with severe thoracic and abdominal pain that radiated into the left flank. His history also included thoracic as well as infrarenal aneurysms, arterial hypertension, compensated renal insufficiency, and nicotine abuse. Epigastric discomfort was elicited on palpation. Serum lipase values had increased to 570 U/L and the total blood count suggested a normocytic anemia (hemoglobin 6.7 g/dL, hematocrit 20.4%). Both cardiac infarction and gastrointestinal perforation were excluded.
Mediastinal widening and a significant left-sided pleural effusion were noted on roentgenogram (Fig 1), while abdominal sonography revealed an inhomogeneous pancreatic structure. Transesophageal echocardiography suggested a dissection of the wall of the descending aorta and showed a large pericardial effusion. Computed tomography confirmed the large pleural effusion as well as a circular pericardial effusion and subphrenic infiltration (density 40 Hounsfield Units). Also seen were what appeared to be a mass due to hemorrhaging (density 50 Hounsfield Units) that had developed behind the heart (Fig 2), and pseudocysts in the pancreatic parenchyma (Fig 3).
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Fig 1. Chest film of the patient on admission, which shows left-sided pleural effusion and mediastinal widening.
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Fig 2. Preoperative computed tomography scan of the chest at the level of the diaphragm. There is a 50-HU dense poorly defined infiltrate adjacent to the descending aorta (arrow).
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Fig 3. Preoperative computed tomography scan of the pancreas showing a pancreatic pseudocyst with a poorly defined upper border (arrow). The scan also shows edema of the peripancreatic retroperitoneal fat (arrowhead).
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The patient was brought to the operating theater under the assumption of the presence of a masked rupture in the distal descending aorta. The operation was carried out with the patient in a lateral position and under endotracheal anesthesia, which used a double-lumen tube. Entry was attained by way of thoracotomy through the fifth intercostal space and a massive pleural sanguineous effusion was evacuated. Extracorporeal circulation (ECC) was effected with femoro-femoral cannulation. Due to the presumed possibility of a masked aortic perforation with massive adherence of the descending aorta to the left lung, the operation was performed under profound hypothermia (16°C) and circulatory arrest. An apical vent was employed to relieve the left ventricle. The left lung was carefully separated from the thoracic aorta. A very coarse and friable mass was encountered (rapid histological section results: inflammatory tissue, no tumor cells), and upon further dissection, a turbid milky secretion appeared. The amylase fraction of this fluid proved to be 105,000 U/L, while the protein fraction was 4.5 g/L. The suspicion of an esophageal rupture could not be endoscopically confirmed. After an incision of the left diaphragm, which extended to the hiatus aorticus, and subsequent evacuation of the subphrenic infiltration, a fistulous passage, which led from the hiatus aorticus in the direction of the pancreas, was seen. This passageway and the pseudocyst that invaded the posterior mediastinum were resected. The patient was weaned, taken off ECC without any untoward events, and decannulated. After placing of drains, the diaphragm and the thorax wall were then closed layer by layer. On the 15th postoperative day, after a massive persistent flow of pancreatic secretions from the drains, an elective median laparotomy was performed. The tail of the pancreas, spleen, gallbladder, and the pseudocysts in their entirety were all removed. The patient was discharged in good condition on the 27th postoperative day.
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Comment
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The mediastinal expansion of a pseudocyst is a rare event [2, 4–8], whose occurrence may either remain clandestine or may indeed lead to a myriad of other adverse complications, such as heart displacement, arrhythmia [6], pericardial effusions [5], dysphagia [8], or aortic autodigestion, which exhibit complications that correspond to the clinical findings. Computed tomography or magnetic resonance imaging may aid in the establishment of a diagnosis. This case illustrates the difficulty of differentiation between an inflammatory mediastinal process and a masked descending aortic perforation.
Acute thoracic discomfort, severe anemia, and a pleural effusion that accompanied a known aneurysm of the descending aorta all indicated the presence of a perforation of the aneurysm in this patient. Neither the computed tomography examination nor the transesophageal echocardiography were able to rule out conclusively a perforated thoracic aneurysm, and therefore, steps were taken for the immediate replacement of the descending aorta. The assumption of a masked aortic perforation dictated the need for profound hypothermia and circulatory arrest. It was only during the course of surgery that the diagnosis of mediastinal paraaortic pancreatic pseudocyst could be established with impunity. Due to the imminent risk of autodigestion of the extremely thin wall of the aneurysm in the event of rupture of the paraaortic pseudocyst, resection of the thoracic portion of the invading growth and drainage of the remnant "cystic vault" were then performed. External drainage usually leads to cystic collapse [6, 8]. However, after 15 days of persistent massive drainage flow, a thorough cleansing of the pancreatic lesions was performed during an elective median laparotomy.
A paraaortally situated cyst in conjunction with a thoracic aneurysm, especially in light of the danger posed by autodigestion, erosion, and/or compression of invariably thin aneurysmic walls, requires preventative resection. The operation should be performed in two stages in the thoracic and abdominal cavities, due to the severity of the potential consequences for the patient.
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Acknowledgments
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We thank Tonie Derwent for assisting in manuscript preparation.
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References
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Accepted for publication September 15, 1999.
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Abstract
Introduction
