Glial fibrillary acidic protein, CD34, Ki-67, and p53 immunohistochemistry expression study to estimate the concordance between the morphology and the awarded grades of the brain gliomas

Background: The 2007 WHO grading system of gliomas recognizes four prognostic grades of the latter. Based exclusively on morphological patterns, this classification remains unsatisfactory with rates of diagnostic conflicts between pathologists ranging from 20% to 50%, particularly between Grades II and III. Misestimating the grade implies impertinent care decisions. We evaluated the concordance between grades and morphological characteristics of our series. Methods: Our study is a retrospective covering 3 years and wherein the biopsies of 32 formalin-fixed paraffin-embedded brain gliomas were explored. The histopathological diagnosis had been revised, and all cases were stained by immunohistochemical (IHC) technique with glial fibrillary acidic protein (GFAP), Ki-67, p53, and CD34 tumor markers. Comparisons were made between the grades and the IHC results and between the latter and the morphological characteristics of the studied gliomas. We used Kolmogorov–Smirnov test for normal distribution, Chi-square test of Pearson and Fisher test for qualitative variables, Mann–Whitney U-test, and Kruskal–Wallis test for continuous variables. The significance is retained for P< 0.05. Results: GFAP is expressed in all of the 32 studied tumors. Our markers are more expressive in high-grade gliomas (GFAP [P = 0.149], Ki-67 [P = 0.001], p53 [P = 0.012], and CD34 [P = 0,004]). Labeling index increases with the cellular density (Ki-67 [P = 0.001], p53 [P = 0.031]) and with the mitotic activity (Ki-67 [P = 0.001], p53 [P = 0.056]). CD34 is more expressive in the presence of endothelial-capillary proliferation (P = 0.02), of palisading necrosis (P = 0.015), and of nonpalisading necrosis (P = 0.076). Ki-67 is more specific and more sensitive than p53 (P < 0.001). The value of ideal expression of Ki-67 proposed for our sample is 8.5% (P < 0.001). It allows 93.7% of specificity and 75% of sensibility and separates the low grade (I, II) of the high grade (III, IV). Conclusion: The results prove the concordance of the established grades and gliomas morphology of our series.