Perineural invasion of hilar cholangiocarcinoma in Chinese population: One center’s experience

BACKGROUND: Hilar cholangiocarcinoma (HCCA) often produces perineural invasion (PNI) extending to extra-biliary sites, while significant confusion in the incidence of PNI in HCCA has occurred in the literature, and the mechanism of that procedure remains unclear. AIM: To summarize the incidence of PNI in HCCA and to provide the distribution of nerve plexuses around hepatic portal to clinical surgeons. METHODS: Reported series with PNI in HCCA since 1996 were reviewed. A clinicopathological study was conducted on sections from 75 patients with HCCA to summarize the incidence and modes of PNI. Immunohistochemical stains for CD34 and D2-40 in the cancer tissue were performed to clarify the association of PNI with microvessel and lymph duct. Sections of the hepatoduodenal ligament from autopsy cases were scanned and handled by computer to display the distribution of nerve plexuses around the hepatic portal. RESULTS: The overall incidence of PNI in this study was 92% (69 of 75 patients), while the rate of PNI in HCCA in the literature ranging from 38% to 100%. The incidence of PNI did not show any remarkable differences among various differentiated groups and Bismuth-Corlette classification groups. Logistic regression analysis identified the depth of tumor invasion was the only factor that correlated significantly with PNI (P < 0.01). In spite of finding tumor cells that could invade microvessels and lymph ducts in HCCA, we did not find tumor cells invaded nerves via microvessels or lymph ducts. Three nerve plexuses in the hepatoduodenal ligament and Glisson’s sheath were classified, and they all surrounded the great vessels very closely. CONCLUSION: The incidence of PNI of HCCA in Chinese population is around 92% and correlated significantly with a depth of tumor invasion. It also should be considered when stratifying HCCA patients for further treatment.