On contrast-enhanced CT of the liver, multiple saccular dilatations of the intrahepatic bile ducts are seen, each containing a small enhancing dot centrally. This 'central dot' sign is characteristic of:

• A Polycystic liver disease
• B Primary sclerosing cholangitis
• C Recurrent pyogenic cholangitis
• D Caroli disease ✓

Explanation

In Caroli disease the congenital saccular dilatation of intrahepatic ducts surrounds the accompanying portal radicles, which appear as enhancing central dots within the dilated ducts on post-contrast imaging. Polycystic liver disease produces non-communicating cysts without central dots, primary sclerosing cholangitis gives irregular short strictures with beading, and recurrent pyogenic cholangitis shows cast-like intraductal stones with periductal enhancement rather than central vascular dots.

Reference: Grainger and Allison Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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