Vasculogenic mimicry is a major feature and novel predictor of poor prognosis in patients with orbital rhabdomyosarcoma.

Vasculogenic mimicry (VM) is a key developmental program, frequently activated during cancer invasion and metastasis. The aim of the present study was to evaluate the role of VM in orbital rhabdomyosarcoma (RMS), the correlation between VM and tumor differentiation, recurrence and survival duration, as well as the contribution of epithelial cell kinase (EphA2) and matrix metalloproteinase-2 (MMP-2) in VM initiation. A total of 32 patients were enrolled to investigate the associations between VM in orbital RMS tumors and clinical characteristics, as well as its impact on overall survival. VM was identified and confirmed by CD31/periodic acid-Schiff double staining, while the presence of EphA2 and MMP-2 were examined by immunohistochemical analysis. VM was identified in eleven patients, particularly those with poorly differentiated orbital RMS (P=0.001). Patients with VM exhibited significantly worse survival rates (P=0.001, log-rank test), a significantly increased risk of mortality (P=0.008) and EphA2 and MMP-2 expression levels were enhanced (P=0.005 and 0.001, respectively). The VM and mitotic rate were independent predictors of poor prognosis (P=0.001 and 0.004, respectively), indicated by multivariate Cox proportional hazards models. These results demonstrated that VM is present in orbital RMS and represents an independent prognostic factor for overall survival. In addition, overexpression of EphA2 and MMP-2 may promote VM formation in orbital RMS.