Detection of Epstein-Barr Virus in Idiopathic Orbital Inflammatory Pseudotumor

Purpose: The etiology of idiopathic orbital inflammatory pseudotumors (IOIP) is unknown. Epstein-Barr virus (EBV) infection, which causes significant lymphocyte infiltration, has been proposed to be involved in IOIP. This study tries to validate the relationship between EBV infection and the development of IOIP. Methods: Eleven surgical samples from IOIP patients and four non-IOIP control samples from surgery removal of eye due to trauma were analyzed by microarray. The data were confirmed by real time RT-PCR. The existence of EBV-DNA segments in IOIP samples was determined by PCR. Results: Hierarchical clustering of microarray data successfully distinguished the IOIP group and the non-IOIP control group. The gene EBI2, usually induced by EBV infection, was significantly up-regulated in the IOIP group (max = 11.7-fold over control). EBV-DNA was detected in 9/10 (90%) of the IOIP samples and in 0/4 of the control samples. Up-regulation of EB12, the immunoglobulin kappa light chain (IGKC) and the immunoglobulin heavy chain gene 1(IGHA1) were detected in the IOIP group compared to the control group. Conclusion: Collectively, these findings suggest that IOIP may be related to EBV infection and IGKC and IGHA1 activation. Furthermore, we hypothesize that the expression of the EBI2 gene may serve as a molecular marker for IOIP. More IOIP patient samples and detection of EBV related genes ( EBER1, EBNA2 and LMP1) expression need to be investigated.