Lymphatic malformations or lymphangiomas are benign (non-cancerous) vascular lesions made of fluid-filled spaces (cysts) thought to occur due to abnormal development of the lymphatic system. In general, lymphatic malformations are categorized into macrocystic, microcystic, or combined depending on the size of the cysts; they are also classified in superficial lesions known as lymphangioma circumscriptum, and more deep-seated lesions (cavernous lymphangioma and cystic hygroma). They are present at birth, although they may be discovered later in life. They are most commonly located in the neck and axilla, but they also occur in the mouth, arm, mediastinum, lung, leg, abdomen and viscera. Some may appear as a tiny blue or red spot while others are massive and affect an entire arm or leg.

The signs and symptoms vary depending on the size and location of the mass; however, lymphangiomas can disfigure affected areas and disrupt the function of nearby organs or tissues. The exact underlying cause is unknown.

Treatment options vary based on the signs and symptoms present in each person but may include surgery.

A lymphatic malformation (lymphangioma) is thought to occur due to abnormal development of the lymphatic system; however, the exact underlying cause is unknown in most cases.

Cystic hygroma (cystic lymphangioma) may occur as part of a genetic syndrome such as Noonan syndrome, Turner syndrome and Down syndrome. In these cases, the lymphatic malformations are likely due to genetic causes, such as a change (mutation) in a gene or an abnormal number of chromosomes (a missing or extra chromosome).

The signs and symptoms of a lymphatic malformation (or lymphangioma) vary depending on the type, size and location of the mass. There are different ways of classifying lymphatic malformations. The classification most frequently used divides these lesions into 2 major groups based on the depth and the size of these abnormal lymph vessels. The superficial vesicles are called lymphangioma circumscriptum. The more deep-seated group includes cavernous lymphangioma and cystic hygroma:

• Cystic hygroma, which is also known as cystic lymphangioma or macrocystic lymphatic malformation, is a red or bluish swelling of the skin in the neck, armpit or groin region that consists of large, fluid-filled spaces. Some say it is a type of cavernous lymphangioma.
• Cavernous lymphangioma is also considered a macrocystic lesion. It is a a bluish or red rubbery swelling under the skin that can affect any area of the body, including the tongue.
• Lymphangioma circumscriptum is a microcystic lymphatic malformation. It appears as a cluster of small, firm blisters most commonly on the shoulders, neck, underarm area, limbs, and in the mouth, especially the tongue. It consists of tiny, fluid-filled spaces and ranges in color from clear to pink, dark red, brown or black.

Other classification includes macrocystic lymphatic malformation, microcystic lymphatic malformation and mixed type.

In general, lymphatic malformations are always present at birth, although they typically grow over time and may become more apparent with age. They are most commonly found in the head and neck region, but can affect almost any part of the body (except the brain). Some may appear as a tiny blue or red spot while others are massive and affect an entire limb (arm or leg). Symptoms usually develop if the lymphatic malformation compresses or blocks nearby body parts or organs. For example, lymphangiomas located in the mouth or neck region can cause dyspnea, speech problems, dysphagia and feeding problems. Certain complications can occur, including recurrent cellulitis, which can cause pain and disfigurement of the affected area, and bleeding, which may lead to pain, hardening or rapid enlargement of the mass.

The best treatment options for lymphatic malformations (lymphangiomas) depend on many factors including the size and location of the mass; the type of mass; whether or not the mass is causing symptoms; and/or the affected person's tolerance of certain procedures. Cystic hygromas and cavernous lymphangioma (bluish or red rubbery swellings under the skin) are often surgically removed; however, other procedures such as sclerotherapy (a solution is injected into the lymphatic malformation, causing it to shrink or collapse), laser therapy or radiofrequency ablation (a procedure where a needle is used to deliver a high-frequency alternating current that destroys abnormal tissue), may be tried depending on the size and location of the mass. Unfortunately, some of these masses may be difficult to remove and they often regrow after surgery.

Lymphangioma circumscriptum (clusters of small, firm blisters) usually require no treatment, although they can be removed with dermabrasion or laser therapy. Like other types of lymphatic malformations, they often recur after removal.