Characteristics of tumor infiltrating lymphocytes in sinonasal mucosal melanoma and prognosis for patients

The significance of tumor infiltrating lymphocytes (TILs) in melanoma has been studied for a long time, but, to date, there has been insufficient research on TILs in sinonasal mucosal melanoma. The purpose of this study was to analyze the correlation between TILs and prognosis for Chinese patients with sinonasal mucosal melanoma, and to clarify the significance of TILs in prognosis. As a retrospective cohort study, 44 cases of malignant melanoma in head and neck mucosa were studied by immunohistochemical staining. The correlation between TIL classification (immune cell infiltration types), CD3, CD4, CD8, CD20, CD45, CD56, and CD68 positive cells, disease progression and prognosis for survival was analyzed. By pairing various factors, RNA sequencing and xCell analysis were performed in another 8 patients with different prognoses to further verify the expression of immune cell subsets in these patients. Immunohistochemistry and cell counting showed that the TIL classification and content of CD3, CD4, CD8, CD20, CD45, CD56, and CD68 positive cells were independent factors influencing progression-free survival, but there was no clear correlation with overall survival. RNA sequencing and xCell immunocyte analysis further confirmed the role of TILs in the prediction of disease progression. CD8+ T cells and natural killer T cells were highly expressed in patients with no disease progression, while Th2 T cells, macrophages and M2 macrophages were highly expressed in patients with disease progression. TILs can be used to predict the prognosis for patients with sinonasal mucosal melanoma. Different degrees and distributions of immune cell infiltration influence disease progression in patients with sinonasal mucosal melanoma. Patients with a diffuse distribution and a high density of infiltrating cells have a better prognosis. A high expression of CD8+ T cells and natural killer T cells, which have an immune killing effect, are beneficial in controlling progression of the disease.