<prompt> Central dot sign is seen in?Primary sclerosing cholangitisLiver HamaomaCarolis diseasePolycystic liver disease  <response>: Ans is c i.e. Carolis disease Carolis disease is a rare congenital abnormality in which there is communicating cavernous ectasia of the intrahepatic biliary ducts. Carolis disease is equivalent to type V choledochal cyst. It is commonly associated with congenital hepatic fibrosis and cystic lesions of the kidney.Patients present in late childhood or early adulthood with cholangitis. Ultrasound and CT shows cystic lesions within the liver. A central dot within the cystic lesions is specific for Carolis disease. The central dot represents the poal vein surrounded by the dilated bile duct. Choledochal cyst A choledochal cyst is an isolated or combined congenital dilatation of the extrahepatic or intrahepatic biliary tree. 