Increased density and diameter of lymphatic microvessels correlate with lymph node metastasis in early stage invasive colorectal carcinoma

To determine whether lymphangiogenesis was associated with the development of colorectal carcinoma and whether the mean maximal diameter of lymphatic microvessels (LMMMD) or lymphatic microvessel density (LMVD) is associated with lymph node metastasis in early stage invasive colorectal carcinoma (T1 carcinoma), we used immunohistochemical staining with podoplanin to measure LMMMD and LMVD in intratumoral (LMMMDit, LMVDit) and peritumoral areas (LMMMDpt, LMVDpt) of T1 carcinomas (n=87). By comparing the LMMMD and LMVD in normal large intestine (n=10), adenoma (n=15), and Tis carcinoma (n=15), we found out that the LMVDpt in T1 carcinoma with lymphatic vessel invasion (LVI) was significantly high (P<0.001), and there was a significant decrease in LMMMDpt in T1 carcinoma (P=0.031). Both LMMMDpt and LMVDpt were significantly increased in the T1 carcinomas, with LVI compared with the T1 carcinomas without LVI (P=0.018, P=0.003). Multivariate analysis revealed that LVI and combined greater LMMMDpt and greater LMVDpt were associated with lymph node metastases (P=0.005, P=0.036). These results indicate that lymphangiogenesis might be induced in the surrounding tumor areas of the T1 colorectal carcinoma with LVI; thus, evaluation of the diameter and density of lymphatic microvessels is important in T1 colorectal carcinoma to predict lymph node metastases.