Aggressive hepatic carcinoma consistent with cholangioblastic cholangiocarcinoma treated with liver transplantation: a retrospectively reclassified case.

Cholangioblastic cholangiocarcinoma, also known as NIPBL::NACC1 fusion hepatic carcinoma, is an extremely rare and diagnostically challenging hepatic tumor. We report the first case in Japan and the first documented case treated with liver transplantation for this entity, retrospectively reclassified from hepatocellular carcinoma. A 24-year-old woman was found to have a large hepatic mass, with imaging showing a giant heterogeneous right-sided tumor and a separate hypervascular lesion in the left lateral segment.　Because the tumor was unresectable, liver transplantation was performed. The explanted liver contained encapsulated tumors showing cystic change and hemorrhage, the largest measuring 22.5 cm. Histologically, the tumor predominantly displayed solid and pseudopapillary growth patterns. Initial immunohistochemistry showed focal positivity for chromogranin A and synaptophysin and absence of hepatocellular markers. Pathologic review 25 years later demonstrated patchy but strong positivity for cytokeratin 19 and inhibin, and the tumor was considered most consistent with cholangioblastic cholangiocarcinoma. Metastatic recurrence developed at 8 months, and the patient died at 28 months after transplantation. This case highlights the heterogeneous features and aggressive behavior of cholangioblastic cholangiocarcinoma. In patients with extensive intrahepatic tumor burden and multifocal disease, liver transplantation may not provide adequate oncologic control, highlighting the importance of accurate diagnosis and therapeutic selection.