We report an 8-month-old male presenting with gingival hemorrhages and nasa
l bleeding as the first symptom of a choledochal cyst (CC). On physical exa
mination, there was a large cystic mass in the right upper abdominal quadra
nt. Laboratory studies on admission revealed moderate liver dysfunction and
a bleeding tendency due to vitamin K deficiency. After administration of 5
mg vitamin K the bleeding tendency disappeared. At laparotomy, a large CC
5 cm in diameter was found and the liver showed moderate cholestasis. The s
udden onset of a bleeding tendency in infants with congenital liver or bili
ary-tract disease may suggest not only biliary atresia, but also CC.