Background: Central nervous system (CNS) tumors which constitute 12% of all tumors. They often present diagnostic dilemmas because tumors ofvarying histogenesis show considerable overlap in morphological features and divergent differentiation. Immunohistochemistry (IHC) has become an important tool in the diagnosisof brain tumors. The judicious use of a panel of selected immunostains is unquestionably helpful indiagnostically challenging cases as an accurate histologicdiagnosis helps in predicting the clinical outcome of various brain tumors. Materials and Methods: A total of 40 consecutive suspected CNS tumours wereevaluated using routine Hematoxylin and Eosin stain. In addition, an IHC panel comprising of glial fibrillary acidic protein (GFAP), S100 protein (S100), epithelial membrane antigen (EMA), vimentin (VIM), synaptophysin (Synapto), neurofilament (NFP), and cytokeratin(CK) were used for confirmation of diagnosis. Proliferation in all cases was assessed using MIB1 labelling index. Results: Astrocytomas occurred most frequently in the study, followed by meningiomas. Other rare tumors included primary CNS lymphomasand mesenchymal tumors. Single case of rare primary CNS synovial sarcoma was also encountered. Grading of the tumors wasdone as per the revised World Health Organization criteria. Conclusion: This study highlights the utility of immunohistochemistry as an adjunct to routine histologic diagnosis for proper classification and grading of CNS neoplasms.

Keywords: Brain Tumors; Histopathology; Immunohistochemistry.