RESUMEN
Context: Brain metastases are the most common intracranial neoplasms. They are often the first symptom of systemic malignancy. Hence, immunohistochemistry (IHC) is of importance in evaluating the origin of brain metastases. Aims: The aim was to detect the primary site of brain metastases and evaluate the role of IHC in diagnosing the same. Materials and Methods: Data of 74 patients of brain metastases with unknown primary was analyzed. IHC was performed in these cases. The histopathological findings were correlated with clinical and radiological data. Results: Of 74 cases in which IHC was done; the most common primary site was lung (51 cases). Even after applying IHC, the primary could not be diagnosed in 10 cases. Conclusion: Brain metastases are often the first indicator of systemic malignancy. Lung is the most common primary site in cases with unknown primary, as deduced by IHC findings.