Abstract: | This article is a report on the first known case of an intrapericardial yolk sac (endodermal sinus) tumor discovered in a 14-month-old girl. The patient presented with a systolic murmur, cardiomegaly, and manifestations of cardiac failure. At surgery a large, friable, intrapericardial mass with no evidence of extrapericardial spread was found. Histologic and immunohistochemical findings were diagnostic of yolk sac tumor. Following initial resection, chemotherapy, and a second resection 13 months after the first, the patient died 24 months after diagnosis. Tumor enlargement was associated with elevated serum alpha-fetoprotein levels. |