Correlation with lymphocyte infiltration, but lack of prognostic significance of MECA-79-positive high endothelial venules in primary malignant melanoma

High endothelial venules (HEVs) are specialized vessels in lymphoid organs, supporting lymphocyte trafficking from the blood. As the presence of these vessels was described recently in tumors, it was proposed that they could facilitate the development of antitumor immune response, resulting in improved prognosis. The aim of our study was to analyze the correlation of the density of HEVs with that of the different immune cell types as well as with the clinicopathologic parameters and the disease outcomes in patients with cutaneous melanoma. Primary melanoma samples of 118 patients were analyzed retrospectively by immunohistochemical labeling and quantitation of vessels stained with the MECA-79 antibody, as well as a panel of eight different immune cell types (CD8+ and CD45RO+ T cells, lymphocytes expressing the CD25, CD134, or CD137 activation markers, FOXP3+ regulatory T cells, CD20+ B cells, and DC-LAMP+ mature dendritic cells). Correlations of MECA-79+ vessel density with that of the immune cells, as well as with clinicopathologic parameters and disease outcomes were evaluated. We showed that the number of MECA-79+ vessels correlates strongly with the peritumoral density of B and T lymphocytes. Moreover, higher HEV numbers were detected in tumors hosting tertiary lymphoid structures as well as in those of axial location compared with the ones in the extremity and in men compared with women, whereas no association was found with patient age, tumor thickness, histologic type or ulceration, or with the survival of melanoma patients. The density of MECA-79+ HEVs in primary melanomas shows a correlation with B and T-lymphocyte density and differences according to the presence of tertiary lymphoid structures, tumor site, and the sex of the patient. However, it has no prognostic value.

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