Abstract

Pericardial cysts are rare, congenital, and benign mediastinal lesions. These cysts are usually asymptomatic unless they reach large sizes. A 47-year-old man with a history of exertional dyspnea was admitted after radiographic detection of atelectasis in the right lower lobe of the lung. Multislice computed tomography of the thorax revealed a well-defined, thin-walled, fluid-filled, and homogenous cystic lesion, measuring 23x14x13 cm and causing atelectasis of the right lower lobe. A right lateral thoracotomy was performed to reach the cyst. A clear cyst fluid amounting to 1,700 ml was drained. The cyst was transparent and thinwalled and had no adhesion to the adjacent tissues. After drainage of the fluid, it was understood that the cyst originated from the pericardium. The cyst wall was resected without any pericardial injury. Histopathological diagnosis was reported as a pericardial cyst.

Intrathoracic mesothelial cysts are congenital lesions resulting from the abnormalities that occur during the development of the pericardial coelom. Primary mediastinal cysts comprise 19% to 25% of all mediastinal masses and they are mostly bronchogenic and pericardial cysts.[1,2] Pericardial cysts are usually asymptomatic, and are detected incidentally on chest X-rays as round and smooth lesions, the most common localization being the right cardiophrenic angle.[2] In this report, we presented a case of giant pericardial cyst causing atelectasis of the right lower lobe of the lungs, which is a rare finding.

Case Presentation

A 47-year-old man with a history of dyspnea on exercise for a year was hospitalized after detection of atelectasis in the right lower lobe of the lung on a chest X-ray (Fig. 1a). On physical examination, arterial blood pressure was 120/70 mmHg, pulse rate was 84/min, and he did not have fever. Multislice computed tomography (CT) of the thorax revealed a well-defined, thin-walled, fluid-filled, and homogenous cystic lesion, measuring 23x14x13 cm and causing atelectasis of the right lower lobe by compressing it upward (Fig 1b-d). Radiologic density of the cyst was +4 Hounsfield units (HU). The lesion was located above the diaphragm, beneath the lower lobe of the lung, and on the left and right of the thoracic wall and heart, respectively. Because hydatid cyst was endemic in our region, we performed serological tests, but they were negative. A right lateral thoracotomy was performed to reach the cyst (Fig 2). A clear cyst fluid as much as 1,700 ml was drained. The cyst was transparent and thin-walled and had no adhesion to the adjacent tissues (Fig. 3a). After drainage of the fluid, it was understood that the cyst originated from the pericardium. The cyst wall was resected without any pericardial injury. Histopathological diagnosis was reported as a pericardial cyst (Fig. 3b).

Fig 1: (a) Plain chest X-ray shows right lower lobe atelectasis. Appearance of the cyst on (b) coronal, (c) sagittal, and (d) axial images of multislice computed tomography.

Fig 2: (a) Intraoperative macroscopic appearance of the intact pericardial cyst and (b) its elevation from the pericardial cyst wall after fluid drainage.

Fig 3: (a) Postoperative macroscopic appearance of the cyst wall and cyst fluid. (b) Histopathological examination showed typical features of a pericardial cyst (H-E x 25).

Discussion

Pleuropericardial cysts are usually diagnosed in the fourth and fifth decades.[2] Their incidence was reported as 1/100,000.[1,3] More than 50% of pericardial cysts are usually asymptomatic and present no findings on physical examination unless they reach a considerable size to cause symptoms.[4] They are usually diagnosed incidentally on a chest X-ray obtained for other reasons. Various symptoms have been reported due to extremely large dimensions and varying localizations.[5] Symptoms that are not associated with compression may also be seen in the presence of infection, rupture, or intracystic hemorrhage. Erosion to the right ventricle wall and vena cava wall was reported in two separate cases, as well.[3,6] Thoracic CT scans usually show a well-defined, thin-walled, and fluid-filled cystic lesion with a density of 0-20 HU.[2] Although the classical anatomic localization is the right cardiophrenic angle, different intrathoracic localizations can be seen. Approximately 51-70% of the cysts are localized in the right and 22-38% are localized in the left cardiophrenic angle, while 8-11% may be found in the posterior mediastinum and hilar, right paratracheal, and paraaortic regions.[5]

In the differential diagnosis of these cysts, Morgagni hernia, pericardial fat pad, and tumors originating from the mediastinum, diaphragm, heart, or pericardium should be considered.[3]

The main surgical procedure for pericardial cysts is surgical resection by thoracotomy.[1-3] Videothoracoscopic resection may also be used for typical pericardial cysts that are not large.[7,8] In the presence of any life-threatening condition such as cardiac tamponade, heart insufficiency, or shock caused by extremely large cysts, needle aspiration may be lifesaving.[6]

References

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4) King JF, Crosby I, Pugh D, Reed W. Rupture of pericardial cyst. Chest 1971;60:611-2.

5) Stoller JK, Shaw C, Matthay RA. Enlarging, atypically located pericardial cyst. Recent experience and literature review. Chest 1986;89:402-6.

6) Okubo K, Chino M, Fuse J, Yo S, Nishimura F. Life-saving needle aspiration of a cardiac-compressing pericardial cyst. Am J Cardiol 2000;85:521.

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