Lymphatic malformations (LMs) constitute one subset of a larger group of so-called vascular malformations, which may affect any segment of the vascular tree, including arterial, venous, capillary, and lymphatic vessels. All vascular malformations can be considered to be the result of errors of embryonic development and can be categorized according to the particular vascular component involved as well as by physiologic flow properties. Thus, there exist slow-flow lesions (which include lymphatic, venous, and capillary malformations); fast-flow anomalies (which contain an arterial component); and complex, combined vascular malformations.