What Causes Pericardial Cysts?

Pericardial cysts are fluid-filled sacs that develop adjacent to the pericardium, most commonly located in the right cardiophrenic angle (the region between the right side of the heart and the diaphragm). The majority of pericardial cysts arise from developmental abnormalities during embryogenesis. Below, we address the question: “What causes pericardial cysts?”

What Causes Pericardial Cysts?

Traditionally, pericardial cysts are thought to result from incomplete fusion of one or more embryonic mesenchymal vortices during the formation of the pericardial cavity via lateral folding of the primitive mesoderm. Alternatively, they may stem from abnormal development of the embryonic pleura—particularly in children—or, rarely, develop secondary to pericarditis. Once diagnosed, surgical excision—complete removal of the cyst—is the preferred treatment approach. Recurrence after complete resection is uncommon.

The precise pathogenic mechanisms are generally categorized into three main theories: First, during embryonic development, the cystic tissue fails to integrate fully with the surrounding mesenchyme, resulting in a discrete cystic structure. Normally, such tissue would incorporate into the pericardium; however, in rare cases, the cyst may represent true pericardial tissue—either communicating with the pericardial cavity via a narrow or wide opening, or remaining entirely separate. Although histologically the cyst may appear continuous with the pericardium, some experts propose that such communication may actually reflect an embryonic anomaly involving aberrant connections between the pericardium and adjacent structures. Second, certain cysts may originate not from the pericardium but rather from the pleura. Histopathological examination does not always reveal continuity with the pericardial cavity. Third, pericardial cysts typically feature a thin, variably thickened fibrous wall, are usually unilocular, and contain clear, serous fluid. Microscopically, the cyst wall is lined by a single layer of flattened mesothelial cells and composed of smooth connective tissue with interspersed smooth muscle fibers.

The above outlines the etiology of pericardial cysts. We hope this information is helpful to you.