Immunohistochemical characterisation and histopathology of astrocytic neoplasms at a tertiary Nigerian hospital

Aim: To describe histological features and pattern of expression of selected markers including epithelial growth factor receptor (EGFR), mutant p53 and mutant isocitrate dehydrogenase-1 (IDH-1R132H) among astrocytic neoplasms at the University College Hospital, Ibadan, Nigeria. Design: A retrospective cross-sectional study involving histologically diagnosed Central Nervous System (CNS) neoplasms between January 2004 and December 2015. Haematoxylin and Eosin Slides of 81 cases of astrocytomas were retrieved, re-cut and reviewed. Ethical clearance was obtained from the ethical board of the hospital. Immunohistochemistry using the Biotin-Streptavidin system was performed with IDH-1 R132H, p53 and EGFR mouse monoclonal antibodies (MOABs) specific against all the cases of astrocytomas under review. All cases were graded and classified using the World Health Organisation (WHO) Classification of Central Nervous System tumours (2016). Membranous and cytoplasmic staining of EGFR and IDH-1R132H mouse monoclonal antibodies, respectively, were regarded as positive while nuclear staining of p53 mouse monoclonal antibody was regarded as positive. The data obtained were analysed with the level of statistical significance set at P <.05. Results: Males constituted a majority of cases, 50 (61.7%). Male-Female ratio was 1.6:1. Mean age was 30.6 years. Tumours were of a higher WHO grade with increasing age, albeit glioblastoma cases tended to present at younger ages. The higher WHO grades were more likely to be located supratentorially. Glioblastomas accounted for most of the diagnosis 39 (48.1%), followed by pilocytic astrocytomas at 23 (28.4%). There was a low positive cytoplasmic expression of IDH-1 with only three (3.7%) being positive, eight (9.9%) showed a positive nuclear expression for mutant p53 while 17 (21%) showed membranous positivity for EGFR expression. Conclusion: There are similar epidemiological trends between our cohort of patients and as described in most instances worldwide. Optimal stratification for astrocytomas can be achieved using a combination of IDH-1/EGFR immunohistochemistry.