Introduction: Aquaporins and astrocytes are important in maintaining water hemostasis in brain. Upregulation of AQP-4 has been described in conditions associated with brain edema.

Aims: To study the expression of aquaporin-4 in brain tumors and its correlation with contrast enhancement and perilesional edema.

Material and methods: 30 cases of brain tumors, both benign and malignant were included in the study to look for expression of AQP-4.

Results: AQP-4 expression was increased in brain tumors compared to normal brain but distribution and intensity of expression depend upon the type of tumor. A trend toward increased AQP-4 expression in enhancing lesions with perilesional edema was noticed.

Conclusion: AQP-4 expression was seen in tumor tissue and perilesional reactive astrocytes in primary brain tumors, however only perilesional astrocytes showed positivity in secondary brain tumors. AQP-4 could be playing a role in alteration of blood-brain barrier leading to contrast enhancement and perilesional edema. Increased knowledge of Aquaporins may open new targeted therapy for brain edema.