Restoration of bile ducts in drug-induced vanishing bile duct syndrome due to zonisamide.

Prolonged drug-induced cholestasis may be due to destruction and disappearance of bile ducts, sometimes referred to as vanishing bile duct syndrome. Although some of these cases progress to fibrosis, cirrhosis, and liver failure, others improve with time. We report a case of a 35-year-old man who developed vanishing bile duct syndrome after ingestion of zonisamide, an antiepileptic drug that is also prescribed for weight loss. His liver biopsy showed complete absence of bile ducts 3 weeks after starting treatment. There was no ductular reaction. The drug was stopped and a follow-up biopsy 3 months later showed strands of intermediate hepatobiliary cells at the periphery of the portal tracts that extended into lobules; these structures lacked lumina and expressed biliary cytokeratins, CK7 and CK19. A third biopsy, 7 months later, showed the presence of ductules with lumina located within portal tracts. Intermediate hepatobiliary cells were rare; although sparse clusters of hepatocytes with membrane staining for CK7 were present. Cholestasis and levels of bilirubin improved over time. The histologic features in this case document the sequence of events in restoration of the biliary tree after loss of bile ducts, which seems to be a process of maturation of intermediate hepatobiliary cells that arise from a proliferative compartment at the porto-hepatic interface.