Congenital deficiency of the pericardial sac has never been correctly diagnosed during life. It is an anomaly which has aroused the attention largely of anatomists and embryologists. But in spite of its rarity we believe it is not without clinical significance.
The first case reported of absence of the pericardium was that of Realdo Colombo in 1559, but it seems probable in the light of present knowledge that this was merely a case of adherent pericardium. The first indubitable example of the condition was that reported by Baillie in 1793. Since then about fifty other cases have been described, but in many instances the protocols have been scanty and in none has the clinical side of the picture been stressed. The unusualness of the condition is further emphasized by the fact that in 1909 Versé found only two examples in thirteen thousand necropsy reports and that the case we are