[Vasculogenic mimicry in the bi-directional differentiation malignant tumors of digestive tract]

To investigate whether vasculogenic mimicry (VM) exists in the bi-directional differentiation malignant tumors of digestive tract.

111 specimens of bi-directional differentiation malignant tumors of digestive tract. including malignant gastrointestinal stromal tumors (GIST, n = 80), malignant melanoma (n = 18), and carcinosarcoma (n = 13), underwent periodic acid Schiff (PAS) staining and microscopy. Immunohistochemistry was used to examine the expression of vascular endothelial growth factor (VEGF), and CD31. Microvascular density (MVD) and vasculogenic mimicry density (VMD) were calculated.

PAS-positive patterned matrix-associated vascular channels with red blood cells therein were detected in 39.1% (31.5/111) of the tumor samples. (89 +/- 20) and MVD (47 +/- 12) both lower than without VM (76, 126 +/- 18, 78 +/- 13, all P < 0.05) the expression levels of VEGF and MVD in the tumors containing patterned channels were (89 +/- 20) and MVD (47 +/- 12) respectively, both significantly lower than those in the tumors without VM [(126 +/- 18) and (78 +/- 13) respectively, both P < 0. 05]. The higher the malignant degree of tumor, the higher the proportion of the tumor with VM. The levels of MVD and VMD of the GIST, malignant melanoma, and carcinosarcoma with low malignancy were 45 +/- 19, 15 +/- 8, and 38 +/- 25 respectively, all significantly lower than those of the GIST, malignant melanoma, and carcinosarcoma with high malignancy (128 +/- 42, 81 +/- 17, 122 +/- 39, all P < 0.05).

VM exists in the bi-directional differentiation malignant tumors of digestive tract. The tumor cells obtain blood supply and become metastatic via the mechanism of VM.