Hepatocellular- cholangiocarcinoma collision tumor: a case report.

Hepatocellular-cholangiocarcinoma collision tumor is an extremely rare primary liver malignancy, defined as histologically distinct hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) growing adjacently with clear demarcation, which is easily misdiagnosed due to overlapping features with combined hepatocellular-cholangiocarcinoma and metastatic liver cancer, and lacks standardized diagnostic and treatment evidence. We report a 54-year-old male with 15-year chronic hepatitis B infection admitted in June 2024 with fatigue, poor appetite and abdominal distension. Preoperative CT initially suggested multifocal metastatic HCC, while Gd-EOB-DTPA MRI indicated dual primary tumors, and multi-target biopsy confirmed HCC-ICC collision tumor (S8 segment grade III HCC, S6 segment moderately differentiated ICC, no mixed components). After multidisciplinary team (MDT: Oncology Department, Interventional Vascular Surgery Department, Hepatobiliary Surgery Department, Radiology Department, Internal Medicine for Liver Diseases Department, Infectious Diseases Department) discussion, the patient was ineligible for surgery due to lymph node metastases, received transarterial chemoembolization for the HCC lesion, followed by sequential PD-1 inhibitor(Sintilimab) plus bevacizumab and 8 cycles of gemcitabine plus cisplatin. As of the last follow-up on April 20, 2026, the patient had an overall survival of over 18 months with partial response lesions and no severe adverse events. This case indicates that HCC-ICC collision tumor should be considered in the differential diagnosis of multifocal liver malignancies, multi-target biopsy is critical for accurate diagnosis, and individualized combination therapy targeting both components can achieve favorable survival outcomes, adding to the clinical evidence for this rare disease.