Pathogenesis of lymphangiomas.

Based on various hypotheses concerning lymphangiogenesis published in the literature, different putative mechanisms of lymphangioma development are discussed including failure of the lymphatic system to connect with or separate from the venous system, abnormal budding of the lymphatic system from the cardinal vein, or acquired processes such as traumata, infections, chronic inflammations, and obstructions. Increasingly, the possible influence of lymphangiogenic growth factors on the development of lymphangiomas is discussed. The proved expression of different growth factors in the endothelium of lymphangiomas leads to new hypotheses regarding the pathogenesis of lymphangiomas. Thus, further studies on the lymphangiogenesis and the development of lymphangiomas will have to clarify as to whether lymphangiomas are true malformations or neoplastic in nature.