A 29 year old male was diagnosed with ulcerative colitis (pancolitis) one year ago. He is currently in remission, though his alkaline phosphatase rose to 215 last month; it was confirmed to be hepatobiliary in origin because GGT was also elevated to a similar degree.
Because his local medical center does not have access to MRCP or ERCP, a liver biopsy was performed to evaluate for primary sclerosing cholangitis. As expected, the biopsy was consistent with the diagnosis of PSC. The classic (though rarely found) onion skin appearance is highlighted in the biopsy specimen above. It represents concentric, circumferential layering of fibrous tissue that surrounds a damaged bile duct.
What is the trigger for PSC? As in many autoimmune disorders, it is multifactorial. The deranged gut microbiota and inflammatory response in UC sends its myriad signals to the liver through the portal ciruculation, and may be partly responsible for the autoimmune trigger.