PRIMARY MELANOMA OF THE SKIN AND CUTANEOUS MELANOMA METASTASES: COMPARATIVE STUDY OF TUMOR MICROENVIRONMENT

Melanoma incidence is steadily increasing in the Western world. Surgery largely controls melanomas in early stages, whereas advanced disease is still a therapy challenge. Cutaneous melanoma comprises different subgroups according to epidemiology, biological behavior, prognostic features, and molecular profiles. The tumor microenvironment rich in lymphocytes (TILs brisk) represents a complex signaling network with a controversial prognostic role. Notwithstanding the continuous crosstalk of melanoma cells with dendritic cells and T-cells in both peripheral blood and lymph nodes, the immune editing (intra and extra cellular signals interaction) is progressively lost. This event represents the main cause of the uncontrolled proliferation of tumor cells as well as of their migration capability to distant sites. Our aim is to investigate the immune cell microenvironment of primary melanoma and their metastasis, to recognize early those patients with a higher risk of systemic recurrence. Skin primary melanomas and their own metastases of the last ten years with a minimum follow up of five years were included in the study. Sections were cut from the most representative paraffin block of each case. A large panel of antibodies is used to identify immune cell subsets (CD4; CD8; TIA-1; Granzyme B; CD25; FOXP3, CD20+, dendritic cells CD1aS100, CD68, CD15). The comparison among these variables and to histopathological parameters (thickness, ulcer, mitosis) and tumor infiltrating immune cells grading (TI-ICs), was realized to define whether a specific immunological hallmark may explain a different behavior among various TI-ICs grades and if they may represent a useful prognostic tool to predict in early stage, high risk melanoma patients.