Case 16. (16 Feb. 1998)


Diagnosis: Pericardial cyst (connected to superior pericardial recess)
                           major differential diagnosis: bronchogenic cyst


The vast majority of mesothelial cysts (pericardial or pleuropericardial) are probably congenital and result from aberrations in the formation of the coelomic cavities. Grossly, the cysts are spherical or oval in shape, thin-walled, and  often translucent: the vast majority are unilocular and contain clear or straw-colored fluid. Of the 72 cysts reviewed by a Mayo Clinic group, 54 were in the cardiophrenic angles and 18 arose at a higher level: 11 of the latter cysts extended into the superior mediastinum. In most cases they range in diameter from 3 to 8 cm but rarely have been reported to be as small as 1 cm or as large as 28 cm. Symptoms are almost invariably absent, most cysts being discovered on a screening chest roentgenogram.

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