A lymphatic malformation (LM) is a cluster of abnormal blood vessels filled with lymphatic fluid. A lymphatic malformation can happen anywhere on the body but are most common on the neck and face. LMs are present at birth, or can appear by two years of age.
The lymphatics serve as a collection and transfer system for tissue fluids. When something disturbs this system, a lymphatic malformation is formed. The excess fluid accumulates and the affected lymphatic vessels enlarge and you see a mass. If the lymph vessels in the face are affected, the face swells because the normal active transport mechanism has been disturbed. These lesions have the following characteristics:
Lymphangioma, hemangiolymphangioma, and cystic hygroma are old terms describing lymphatic malformations. Lymphangioma was a more common term for Lymphatic Malformations, which used to be called cystic hygroma or hemangiolymphangioma.
The lymphatics collect excess fluid from the tissues and transport it through a series of small vessels back into the venous system. With lymphatic malformations, the transfer of this fluid through these vessels is slowed by an unknown process. The excess fluid accumulates within these vessels and dilates them, resulting in a swelling of the affected area. For example, if the lymph vessels within a particular area of the face are affected, that side of the face will swell up because the normal active transport process has been disrupted, and the malformation results.
Lymphatic malformations can involve any part of the body, but most of them occur in the head and neck area. In certain locations, the dilated lymph vessels (or cystic spaces) tend to be large, known as “macrocystic.” In other areas, they tend to be small, known as “microcystic.” Microcystic lymphatic malformations tend to occur in the facial area. Macrocystic lesions, previously know as cystic hygromas, are more common in the neck. Microcystic lymphatic lesions tend to be more widespread than macrocystic lesions.
As with all other vascular lesions, lymphatic malformations may be superficial or deep, localized or diffused. Superficial lesions in the mucous membrane of the mouth are small fluid filled vesicles, sometimes referred to as “frog’s eggs” (see picture at right). Superficial lesions on the skin are small, fluid-filled vesicles. Medical texts refer to them as lymphangioma circumscriptum. It’s important to remember that these vesicles are usually connected to much larger, deeper cystic spaces. Destroying only the superficial vesicles, without any treatment of the underlying malformation, will result in a recurrence.
Lymphatic malformations steadily increase in size. Some will enlarge more rapidly than others. Certain conditions such as infection and trauma can result in a sudden, but temporary, expansion of the lesion. It’s common for a lymphatic malformation of the head and neck to enlarge due to an upper respiratory infection, and then diminish when the infection subsides. No one knows why this happens. In extremely rare cases, a lymphatic malformation can disappear. It’s unwise to delay treatment in the hope the lesion will spontaneously disappear since it happens so rarely.