Gliomas: Immunohistochemical Grading And Clinico-pathologic Correlations At Kenyatta National Hospital

Abstract

Background: Gliomas are the most common primary central nervous systemtumors, accounting for 48% of primary brain neoplasms. These are tumours arising from glial cells in the brain namely astrocytes, oligodendrocytes and ependymal cells all grouped into 24 tumour variants in the World Health Organization 2000 classitication Broad objective: To carry out immunohistochemical studies on all gliomas, and classify them according to the WHO grading system 2000 and correlate these with surgical and radiological diagnosis. Design: A retrospective cross-sectional study. Study subjects All 102 patients operated on and diagnosed as having gliomas at KNH over a period of five years from January 2002 to December 2006. Setting: Kenyatta National Hospital histopathology laboratory and Kenya Medical Research Institute- Mbagathi Nairobi. Methods: Patients' data and histological reports were analyzed in order to identify those who had been diagnosed to have gliomas. Patients , diagnosed with gliomas during the study period were included. The patients' surgical and radiological diagnoses were retrieved from their files. A proforma form was used to key in patients' clinical and radiologic information. Histology was done using paraffin embedded blocks, which were retrieved from the library using the backup reports in the laboratory library. Routine HIE staininq was done first, then immunohistochemical markers, glial fibrillary acid protein (GFAP), and Ki67 a cellular proliferative marker for grading. The data collected was entered into spreadsheets in the computer and processed using statistical package for social sciences. The results were then presented in form of charts, tables and figures. Results: The most prevalent glioma analyzed was grade I (pilocytic) astrocytoma at 25%, followed by glioblastoma multiforme at 17.8%. Majority of the patients were male at 57%. High-grade lesions, grades III and IV gliomas were common among patients above 15 years and also amongst male patients. Correlations between radiological, surgical and histological diagnosis was very poor at 16%. All gliomas analyzed were reactive to GFAP and ki67 staining was useful in grading of the tumours and in differentiating low-grade astrocytomas from gliosis. The project was carried out over a period of one year. Conclusion: The use of Immunohistochemistry is usefulin the routine histological diagnosis and grading of gliomas at Kenyatta national hospital and the need for complete clinical and radiological detail of the patient is important for correct histological interpretation. We recommend that a standard proforma or request form be developed and adhered to for reporting brain tumours and that GFAP and ki67 Immunohistochemical panels be introduced in the laboratory for diagnosis of gliomas.