Pattern and extent of intrahepatic infiltration of perihilar cholangiocarcinoma - A case-control study based on liver panoramic digital pathology

Background: The extent of intrahepatic infiltration of perihilar cholangiocarcinoma (PHCC) remains unclear. This research aimed to explore the pattern and extent of intrahepatic infiltration of PHCC to guide surgical treatment and pathological research. Materials and Methods: This study included 62 patients diagnosed with PHCC who underwent major hepatectomy. A whole-mount digital liver pathology system (WDLPS) for hepatectomy specimens greater than 10 × 10 cm was used to panoramically assess the intrahepatic infiltration extent of PHCC. Results: The distal intrahepatic infiltration (DIHI) and radial liver invasion (RLI) were important parts of intrahepatic infiltration for PHCC explored by WDLPS. The study confirmed that 75.8% of PHCCs had RLI and the infiltration distance in all patients were within 15,000 µm, 62.9% of PHCCs had DIHI greater than 1 cm away from the main tumor in liver parenchyma. The recurrence-free survival rates and overall survival rates of patients with DIHI were poorer than the patients without DIHI (P＜0.0001, P =0.0038). Arterial invasion on the resected side could be an excellent predictor. A total of 105 liver lobes were resected from 62 PHCC patients. The invasion rates of the left lateral, left medial, right anterior, and right posterior lobe of PHCC were 79%, 100, 100%, and 69% respectively. Conclusion: The presence of DIHI in most PHCCs was a significant predictor of poor postoperative recurrence and survival. Based on the extent of intrahepatic infiltration, minor hepatectomy was not suitable as the curative surgery for PHCC. Major hepatectomy and liver transplantation were the ideal radical treatment.