Expression of vascular endothelial growth factor in human ocular adnexal lymphoma

To examine the expression of VEGF in extranodal marginal zone B-cell lymphoma (EMZL) and reactive lymphoid hyperplasia (RLH) of human ocular adnexa, and analyze the correlation with the intratumoral microvessel density (MVD).

Twenty-two EMZL and 16 RLH tissues were examined in this study. Paraformaldehyde-fixed, paraffin-embedded tissue sections were processed for immunohistochemistry with antibodies against VEGF and CD20. Vascular endothelial growth factor expression was analyzed using the ELISA and RT-PCR in the EMZL tissues. Microvessel density was determined based on the immunoreactivity for anti-CD34 antibody.

Vascular endothelial growth factor immunoreactivity was detected in the cytoplasm of lymphoid cells in EMZL and RLH. ELISA and RT-PCR confirmed VEGF protein and mRNA expressions in the EMZL tissue, respectively. Vascular endothelial growth factor-immunopositive rate in B-cells was significantly higher in 12 conjunctival EMZLs than four RLHs (P < 0.01) and 10 orbital EMZLs than 12 RLHs (P < 0.05). The MVD showed a significant positive correlation with the VEGF-immunopositive rate in conjunctival and orbital EMZLs.

This study demonstrated increased VEGF expression in human conjunctival and orbital EMZL compared with that in RLH, suggesting that VEGF plays a significant role in the pathogenesis and tumor angiogenesis of ocular adnexal lymphoma.