Objective: To explore if vasculogenic mimicry (VM) exists in bi-directional differentiation malignant tumor.
Methods: New sections were made from 158 paraffin sections of bi-directional malignant tumors, including malignant melanoma (n = 60), synoviosarcoma (n = 39), rhabdomyosarcoma (n = 29), malignant mesothelioma (n = 26), and epithelioid sarcoma (n = 4). The representative points in the paraffin sections were labeled and two tissue microarrays were made, one including 60 cases of malignant melanoma, and the other including the other tumors. Immunohistochemical staining of platelet-endothelial cell adhesion molecule (CD31 antigen) and periodic acid Schiff (PAS) staining were conducted. Microscopy was made and the areas of vessel-like channels consisted of CD31 antigen-positive tumor cells and of PAS positive material were calculated.
Results: PAS positive material or CD31 positive material were observed in these bi-directional tumor cells. In the tumors vessel-like channels could be found, made of PAS positive material lined with CD31 negative tumor cells and red blood cells inside the channel, or made of tumor cells with CD31 positive material. The area of the former vessel-like channels was significantly smaller than that of the latter (P < 0.01). VM was found in 16 of the 39 cases of the highly malignant synoviosarcoma and acinar type rhabdomyosarcoma, a ratio higher than that among the cases of synoviosarcoma and acinar type rhabdomyosarcoma with lower malignancy (5/29) (P < 0.05).
Conclusion: VM exists in bi-directional differentiation malignant tumors.