Central dot sign on CT scan is seen in

Caroli disease is a congenital disorder comprising of multifocal cystic dilatation of segmental intrahepatic bile ductsalso classified as a type V choledochal cyst, according to the Todani classificationPathologically, belongs to the spectrum of fibropolycystic liver disease which results from in utero malformation of the ductal plateTwo types - simple and peripoal fibrosisImaging features:CT/US/ MR:central dot sign = poal vein radicles completely surrounded by dilated bile ductsCholangiography (diagnostic):segmental saccular/fusiform/beaded dilatation of intrahepatic bile ducts extending to the periphery of liver up to 5 cm in diameterbridge formation across dilated luminaintraluminal bulbar protrusionsfrequent ectasia of extrahepatic ducts + CBDComplications:Intraductal stonesCholangitis and AbscessLiver cirrhosisCholangiocarcinomaTodani classification:(Ref: Grainger and Allison&;s diagnostic radiology 6th edition, page 797)