Definition:

Lymphangiomas are congenital malformations of the lymphatic system, which is located mostly on the head and neck region. The lesions consist of dilated endothelium-lined spaces that vary in size from microscopic channels (cavernous lymphangioma) to large cysts (cystic hygroma). Although histologically benign, these lesions may expand into surrounding tissues and/or infiltrate vital structures similar to malignancies, sometimes causing life-threatening complications. The etiology of lymphangioma is not certain. The presence of lymphatic endothelial cell (LEC)-specific markers on the endothelial lining of lymphangiomas (e.g. the transcription factor Prox1) indicates that the neoplasm may result from transformed LECs and/or stromal cells. This transformation is modulated by VEGF-C, a specific lymphatic endothelial growth factor, and its receptor VEGFR-3.