Lymphatic spread is related to VEGF-C expression and D2-40-positive myofibroblasts in intrahepatic cholangiocarcinoma

Lymph node metastasis via lymphatic vessels is related with an adverse outcome in many tumors. It is unclear whether lymphatic spread needs the development of the new lymphatic vessels or the expression of lymphangiogenetic factor in intrahepatic cholangiocarcinoma. The aim of this study was to assess the role of lymphangiogenesis, vascular endothelial growth factor-C (VEGF-C) expression, and D2-40-positive myofibroblastic cells for lymphatic spread and patient outcome in 88 cases of intrahepatic cholangiocarcinoma. We also assessed VEGF-C expression in 15 cases of metastatic lymph nodes. There was a significant correlation between lower lymphatic vessel density in the tumor center and positive lymphatic invasion (P=0.0100). Poorly differentiated cholangiocarcinoma showed higher lymphatic vessel density in the tumor periphery and in the peritumoral area (P=0.0315 and P=0.0360, respectively). Lymphatic invasion was observed higher in the peritumoral area (63%, 24/38) and in the tumor periphery (79%, 30/38) than in the tumor center (27%, 9/38). There was no significant correlation between the proliferative lymphatic vessels and pathologic features; however, lymphatic invasion was significantly associated with VEGF-C expression (P=0.0006), and the VEGF-C expression was seen in 12 of 15 cases (80%) of metastatic lymph node. Nodal metastasis was correlated with D2-40-positive myofibroblasts (P=0.0161). VEGF-C expression was an independent prognostic factor by multivariate survival analysis (P=0.0131). Our findings suggest that VEGF-C has an important role in lymphatic invasion via the preexisting lymphatic vessels in the tumor margin, and that lymphangiogenesis does not play a direct role in lymphatic metastasis. D2-40-positive myofibroblasts may contribute to lymphatic metastasis.