MSFinals-1501

A 40-year-old male with a history of Ulcerative colitis (UC) presents with fatigue, abdominal pain, and generalized itching. During the examination, he is found to be jaundiced, and his blood tests reveal a significantly elevated bilirubin and alkaline phosphatase. An MRCP indicates the presence of multiple strictures in the biliary tree.

What is the probable diagnosis?