Medulloblastom Subtiplendirmesinde İmmunohistokimyasal Yaklaşım

Abstract

While medulloblastomas being the most observed malign brain tumor of childhood are classified based on histomorphology in DSÖ 2007 classification, they suggest the reaching of diagnosis by integrating DSÖ 2016 molecular group and histological phenotype. The use of molecular subtypes is suggested by taking the gene expression and methylation profiles in direction of the developments experienced in molecular pathology in recent years. In this respect, 4 subtypes have been determined under the names of WNT, SHH, Group 3 and Group 4. In this study, medulloblastoma cases between 1981-2015 at Pathology Department of Hacettepe University Medical School have been examined. Cases that can be reached in terms of demographic data and that include sufficient amount of tissue in paraffin embedded blocks are included in the study. Sections obtained from tissue indexes to be created by tissues embedded in formalin fixed paraffin have been used for immunohistochemical protein (β-katanin, GAB1, YAP1, Filamin A and p53 antibody panel) expression and FISH methods (N-myc and C-myc amplification existence). Tumors have been re-evaluated according to epidemiologic features such as age, gender and clinical features such as recurrence and showing dissemination. At our department, sections belonging to 218 patients with medulloblastoma diagnosis have been re-examined according to their histomorphological features; the relationship between molecular medulloblastoma subtypes and histopathological phenotypes with clinical information such as survival and prognosis of patients. Defining statistical studies for all variables have been done and the relationships among categorized variables have been evaluated with Fischer exact and Fischer-Freeman-Halton tests; for survival analysis Kaplan Meier survival curve has been used. In this study, tangible data will be reached in medulloblastoma subtypology by combining immunohistochemical method results and histomorphological features without needing molecular methods. This situation will provide patients in a more aggressive group with an intense treatment protocol and prevent the unnecessary treatment of patients in subgroups with a better prognosis.