Co-expression of VEGF-C and its receptors, VEGFR-2 and VEGFR-3, in endothelial cells of lymphangioma. Implication in autocrine or paracrine regulation of lymphangioma.

Lymphangioma has long been thought of as congenital malformations resulting from the failure of lymphatic vessels communicating with the venous system in the fetal period. Alternatively, it is proposed to be true neoplasm originated from the transformation of lymphatic endothelia. To extend the molecular basis of the pathogenesis of lymphangioma, we have characterized the expression of vascular endothelial growth factor (VEGF) and VEGF receptors (VEGFR) in 29 cases of lymphangioma by RNA in situ hybridization. Endothelial cells of lymphangioma co-express transcripts of VEGF-C and its receptors VEGFR-3 (Flt4) and VEGFR-2 (Flk1), which are not detectable in the adjacent connective tissue. In contrast, there is little or no expression of VEGF-C, VEGFR-3, and VEGFR-2 mRNA in endothelial cells of hemangiomas, angiosarcomas, or normal lymphatic vessels of the small or large intestines. The results suggest that VEGF-C and its receptors may take active parts in the formation of lymphangioma by autocrine or paracrine regulation.