This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
Central dot sign is seen in: 
Select and explain. 
A. Caroli's disease, B. Primary sclerosing cholangitis, C. Polycystic liver disease, D. Liver hamaoma
A: Caroli's disease
Answer: A: Caroli's disease 
Explanation: A. i.e. Caroli's disease Central dot sign is considered pathognomonic of carolis diseaseQ. This sign consists of cystically dilated intra hepatic biliary radicles with a "dot" of increased density represented by poal radicle with the lumen of duct. Caroli's disease Communicating cavernous ectasia of the intrahepatic bile ducts. (IHBD). - AR congenital disorder - Segmental, saccular dilatation of the IHBD. - A/W: - Choledochal cyst and - AR polycystic kidney disease (ARPKD) Signs Disease Central dot signQ Caroli's disease Pruned- Tree appearance / Beaded appearenceQ / Skip lesions Primary sclerosing cholangitis Light bulb appearance Liver Hemangioma (on T2W MRI) Water lily sign /HoneycombingQ Liver hydatid