Application of EGFR, ki 67 and GFAP as a panel for the diagnosis and grading of astrocytomas

Background: Astrocytic tumors are the most common primary central nervous system tumors. WHO grading scheme is based on the presence or absence of the following four histological parameters using haematoxylin and eosin (H&E) staining: cellular atypia (WHO grade II), mitotic figures (WHO grade III), endothelial proliferation, and/or necrosis (WHO grade IV). Immunohistochemistry (IHC) has become an essential tool in diagnosis of brain tumors and helps in predicting the prognosis of certain brain including astrocytomas. Aim: Study the immunohistochemical expressions of (Epidermal growth factor receptor (EGFR), Ki67 and Glial fibrillary acidic protein (GFAP)) in different grades of astrocytomas. Materials and Methods: This study included 44 cases of astrocytomas classified as: 3 pilocytic astrocytomas, 6 diffuse low grade astrocytomas, 15 anaplastic astrocytomas and 20 glioblastoma multiforms. Immunohistochemical staining of all cases using EGFR, Ki67 and GFAP was done. Results: EGFR showed positive membranous and cytoplasmic expression in 33 (75%) cases, GFAP positive staining was detected in 38 (86.4%) of studied cases while all astrocytomas of different grades showed ki67 positivity with variable degrees with the mean ± SEM of Ki67 LI 17.76% ± 2.46. There was statistically significant relation between EGFR, Ki 67 and GFAP expression and tumor grade. Conclusions: EGFR, Ki 67 and GFAP should be used in combination as a panel side by side with established histological criteria of malignancy and WHO grading system for accurate diagnosis and grading of astrocytic tumors.