Ann Thorac Surg 2004;77:701-702
© 2004 The Society of Thoracic Surgeons
Case report
Migrating pleural mesothelial cyst
Michael J. Walker, MDa*,
Steven C. Sieber, MDa,
Shaliz Boorboor, BSa
a Departments of Thoracic Surgery and Pathology, Danbury Hospital, Danbury, Connecticut, USA
Accepted for publication May 8, 2003.
* Address reprint requests to Dr Walker, 27 Hospital Ave, Suite 405, Danbury, CT 06810, USA
e-mail: michael.walker{at}danhosp.org
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Abstract
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We herein describe an atypical presentation of a migrating coelomic cyst attached to a pedicle of pericardial fat pad in an asymptomatic 45-year-old woman. A review of the English-language literature revealed only one such case report.
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Introduction
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Mesothelial or coelomic cysts of the mediastinum and pleura are uncommon cysts that are usually asymptomatic and found incidentally by imaging tests. They may be classified as one of two types: pleuropericardial cysts and other mesothelial (pleural) cysts [1]. We report a case of a mesothelial cyst that differed in location on follow-up computed tomography (CT) scan. The cyst was removed by thoracoscopy, as it was not a defined pleuropericardial cyst as originally thought.
A 45-year-old woman with vague right upper quadrant pain underwent magnetic resonance cholangiopancreatography (MRCP), which revealed a mediastinal mass along the right lateral border of the heart. Computed tomography scan of the chest performed June 2002 revealed a 5.4 x 2.1-cm ovoid cystic structure abutting the right atrium (Fig 1A).
Transesophageal echocardiogram revealed a 5-cm pyramidal-shaped cyst adjacent to the right atrium. It could not be determined whether the cyst was in the pericardial or pleural space. Subsequent CT scan on December 2002 revealed the cystic structure to have migrated to the inferior portion of the major fissure (Fig 1B). Thoracoscopy revealed a mobile cystic structure lying on the anterolateral aspect of the right pericardium attached to a long stalk of pericardial fat pad. The lesion was completely excised with a generous base of fat pad using an endoscopic stapler. Histologic evaluation disclosed a thin-walled cyst lined by typical cuboidal mesothelial cells and a thin layer of dense collagen consistent with a mesothelial or coelomic cyst. The cyst was completely excised, and no communication with the pericardium could be identified (Fig 2).
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Fig 1. (A) Computed tomography scan showing cyst location along pericardial surface (bar). (B) Computed tomography scan identifies "migratory" cyst now in major fissure (bar).
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Comment
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Review of the English literature has identified one such migratory pleural cyst [2] as found in our patient. Lambert theorized that the pericardium is formed from separate lacunae that merge later in embryonic life [3]. Lillie and associates associated mesothelial cysts with persistence of the ventral pericardial recess after embryonic development [4]. Mesothelial cysts may have broad interfaces with the pericardium (typically called a pericardial cyst) or be found in atypical places such as the anterior mediastinum or paravertebral area [5] if the ventral parietal recess diverticular neck has been completely pinched off. Therefore, the majority of pleuropericardial cysts are found in the right costophrenic angle. These cysts are lined by typical mesothelial cells and filled with clear fluid.
The majority of typical pericardial cysts may be treated expectantly with interval imaging. These "typical" cysts are simple, unilocular abnormalities with low attenuation found in the costophrenic angle. Percutaneous needle drainage with cytologic evaluation of the fluid may be considered, but is not necessary. Surgical resection or needle drainage is advocated for symptomatic cysts and lesions that cannot be considered "typical." These include multiloculated cysts and cysts with a higher attenuation than expected with a "typical" cyst. We elected to remove this cyst, as it did not appear to behave as a typical mesothelial cyst, migrating on a stalk of pericardial fat pad. We favored resection over percutaneous drainage, as this did not represent a "typical" cyst. Localized fibrous tumors can also occur on a stalk and can migrate. We believe the cyst migrated secondary to gravity, because the cyst was found on the dependent surface of the pericardium with the patient in the left lateral decubitus position as found with the first CT scan. This case presentation should inform thoracic physicians to the occurrence of a benign migrating mesothelial cyst.
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References
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- Shields T.W. Mesothelial and other less common cysts of the mediastinum. In: Shields T.W., ed. General thoracic surgery. Philadelphia: Lippincott, Williams, & Wilkins, 2000:2423-2427.
- Shin M.S., Tyndall E.G., Ronderos A.D. Pedunculated pericardial coelomic cyst manifesting as a rolling intrapleural mass. Chest 1973;63:123-124.[Abstract/Free Full Text]
- Lambert A.V.S. Etiology of thin-walled thoracic cysts. J Thorac Surg 1940;10:1.
- Lillie W.I., McDonald J.R., Clagett O.T. Pericardial coelomic cysts and pericardial diverticula. J Thorac Surgery 1950;20:494.
- Klein D.L. Pleural cyst of the mediastinum. Br J Radiology 1978;51:548-549.[Abstract/Free Full Text]
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Abstract
Introduction
