Objective: To explore the incidence of perineural invasion (PNI) in hilar cholangiocarcinoma (HCCA) and summarize the distribution pattern of nerve plexuses around porta hepatis.
Methods: Reported series on PNI in HCCA were systematically reviewed. A clinicopathological study was conducted on sections from 75 HCCA patients to summarize the incidence and modes of PNI. Immunohistochemical stains for CD34 and D2-40 in tumor tissue were performed to clarify the association of PNI with microvessel and lymphoduct. Sections of different decks of hepatoduodenal ligament from 5 autopsy cases were scanned and computerized to display the distribution of nerve plexuses around porta hepatis.
Results: The incidence of PNI in HCCA in literature ranged from 59.2% to 100%. In the present study, the overall incidence of PNI was 92.0% (69/75). However, the incidence of PNI showed no remarkable differences among various differentiated groups and Bismuth-Corlette classification groups. Tumor cells could invade microvessels and lymphoduct in HCCA. But no invasion of nerves occurred via microvessels or lymphoduct as demonstrated by immunohistochemistry. Three nerve plexuses in hepatoduodenal ligament and Glisson's sheath were classified and they all surrounded great vessels very closely.
Conclusion: PNI is generally underreported in HCCA. A surgeon should handle diligently the nerve plexuses around porta hepatis.