Assessment of tumoral and peritumoral inflammatory reaction in cutaneous malignant melanomas.

Abstract

Skin cancer is one of the most common types of cancer, with an increasing worldwide incidence in recent decades. The main risk factor for increasing the skin cancer incidence is ultraviolet (UV) radiation. Of the two major forms of skin cancer (melanomas and non-melanotic cancers), the cutaneous melanoma (CM) is the most aggressive form, causing about 80% of the deaths resulted from this type of tumor. Malignant melanoma develops through malignant transformation of melanocytes in the skin because of prolonged exposure to solar or artificial UV. The malignant transformation of the melanocytes in the skin is accompanied by the presence of a local inflammatory reaction that, in the initial stages of carcinogenesis, would oppose to tumor development. Chronic exposure to UV or other etiopathogenic factors induces chronic inflammation, which, by producing inflammatory molecules (cytokines, chemokines, prostaglandins), constitutes a tumoral microenvironment that favors carcinogenesis, tumor invasion, metastasis, and the presence of neoplastic "mutant cells" that avoid the protective action of the immune system. Using immunohistochemistry techniques, we assessed the intra- and peritumoral inflammatory infiltrate cells in CM. The chronic inflammatory infiltrate presented more intense in the peritumoral stroma compared to the intratumoral one, heterogenous, more intensely composed of lymphocytes, plasma cells, macrophages, and mast cells (MCs), the most numerous cells in the inflammatory infiltrate being T-lymphocytes, plasma cells and macrophages; B-lymphocytes and MCs were in a small number, especially intratumorally. Inflammatory cells had a direct contact with tumor cells, blood vessels, connective matrix, suggesting that the inflammatory microenvironment plays an important role in carcinogenesis, tumor invasion, local angiogenesis, and tumor metastasis.