A somewhat confusing array of investigations

A full house of cholangiogram, cholangioscopy and histology of a 35 year old man with jaundice!
WHAT IS THE DIAGNOSIS?

■ Autoimmune hepatitis

But this should be diagnosed by blood tests?!

■ Alcoholic hepatitis

The last thing a patient would need is an ERCP

■ Primary Billiary Cirrhosis

But it's a man!

■ Primary Sclerosing cholangitis

Got it!

explanation

This is of course something of a curveball.  Why would a patient with any of these causes of jaundice undergo an ERCP? Surely a clinical assessment, blood tests and an MRI would be the investigation of choice?  Without any risk of giving the patient cholangitis!?  Actually, the three images (cholangiogram, cholangioscopy and histology) are from three historical cases ☺! 

MRI has a sensitivity of about 85% and specificity of around 95% for PSC. In most cases of PSC (87%), both intra and extra-hepatic bile ducts are involved , intrahepatic ducts alone in 10-25% and very rarely only the extrahepatic ducts (2%). 

Cholangioscopy shows patches of inflammation on the wall of the CBD and the cholangiogram did suggest some 'pruning' of the intra-hepatic biliary tree.  A subsequent liver biopsy (we really did go all out), shows the typical peri-portal 'onion skin' inflammatory changes in keeping with PSC (although histology can't usually completely rule out other causes of biliary obstruction).