Expression of Annexin A1 and UCH-L1 in central nervous system neuroepithelial tumors

Background: Pathological diagnosis of CNS neuroepithelial tumors can be problematic due to morphological similarity, and many tumors in the group share immunohistochemical profile. New markers are needed to enhance histologic diagnosis.

Objective: We studied Annexin A1 and UCH-L1 expression in CNS neuroepithelial tumors, with regard to a possible application for practical usage.

Methods: Expression of Annexin A1 and UCH-L1 was evaluated in 224 various neuroepithelial tumors by immunohistochemistry using tissue microarrays.

Results: Annexin A1 was expressed by the majority of ependymoma (92%) but none of central neurocytoma (p = 0.0000002) and medulloblastoma (p <10^-8). Absence of Annexin A1 and/or UCH-L1 was associated with low-grade astrocytoma rather than ependymoma (p = 0.0000009). Percentage of positive Annexin A1 and UCHL1 paralleled increasing histologic grades in diffuse astrocytomas.

Conclusion: Expression of Annexin A1 distinguishes ependymoma from central neurocytoma, and from medulloblastoma. Demonstration of Annexin A1 and/or UCH-L1 might be helpful to differentiate ependymoma from low-grade astrocytoma. Up-regulation of Annexin A1 and UCH-L1 in increasing histologic grade of diffuse astrocytomas suggests their roles in the malignant transformation.