Investigation of the relationship between microsatellite instability and immune control checkpoint inhibitors like pd-l1 and galectin-9 in intradermal nevi, primary and metastatic melanomas in selected cases diagnosed between 2010-2017 in Karadeniz Technical University Faculty of Medicine department of Medical pathology

Malignant melanoma; is the origin of the neural crest, that is the result of malign transformation of melanocytes responsible for pigment production in the basal layer of the epidermis, usually resistant to conventional treatments, with high metastatic capacity. In recent years, there has been an increase in the incidence of malignant melanoma worldwide. Although only 3 % of all skin cancers are melanoma, 65 % of deaths due to skin cancer are caused by melanoma. Although melanoma frequency is relatively rare compared to many other cancer types, it is of great importance due to high mortality rates. This is why melanoma prevention and early diagnosis should be done to ensure rapid access to potential treatment it is important. In our study, the relationship with MLH-1, PMS-2, MSH-2 and MSH-6 immunohistochemical profiles and PD-L1 and Galectin-9 immune control checkpoints inhibitors in 100 selected (intradermal nevi, primary and metastatic malign melanoma) cases between the years of 2010 to 2017 and are compared age, sex, morphological characteristics. Microsatellite instability was not detected in % 91,1 of malignant melanoma cases. Microsatellite instability was detected in % 8,9 of the cases. The incidence of microsatellite instability and the expression of PD-L1 and Galectin-9 were found to be higher in metastatic melanomas than in primers (primary melanomas). Distinct treatment modalities have been implicated in malignant melanoma, including tumor-infiltrating lymphocytes. Chemotherapy, palliative radiotherapy and immunotherapy, which has emerged as a promising treatment in recent times, are used in the treatment of advanced stage 3 or 4 patients. One of the main goals is to reactivate the immune system with immunocontrol inhibitors. Especially in metastatic cases, both microsatellite instability and PD-L1 and Galectin-9 expression were higher, suggesting that tumor immunogenicity was increased and immune checkpoint inhibitors were expressed more and these patients would benefit more from immunotherapy drugs. In addition to anti-PD-L1 immunotherapy, our study also brought up new treatment options targeting Galectin-9.