Lymphatic malformation is a condition where lymph vessels develop abnormally before birth, forming fluid-filled cysts that can appear anywhere in the body. Though these growths are not cancerous, they can cause swelling, discomfort, and sometimes serious complications depending on their location and size.
Understanding Lymphatic Malformations
A lymphatic malformation develops when abnormal lymph vessels form clusters of disorganized, spongy cysts. These unusual growths happen because the lymphatic system doesn’t develop properly during pregnancy. The lymphatic system is a network of tubes and organs that moves a clear, pale yellow fluid called lymph throughout the body. This system is crucial for fighting infections and maintaining the body’s fluid balance by draining extra fluid from tissues and returning it to the bloodstream.[1]
When lymphatic malformations form, the lymph fluid cannot drain properly from the abnormal vessels. These vessels usually remain separate from the normal lymphatic system, which means the fluid becomes trapped. As lymph accumulates, the vessels and cysts stretch and swell, causing the malformation to grow larger over time. This swelling is sometimes called a flare.[1]
The walls of lymphatic malformations contain fragile, malformed veins that bleed easily. When these vessels bleed internally, the malformation fills with blood, which adds to the pooling lymph and causes further stretching. If the malformation is close to the skin surface, it may appear bruised or discolored.[1]
Lymphatic malformations are entirely benign, meaning they are not cancerous and do not spread to other parts of the body. However, as they grow, they can put pressure on nearby structures such as the eyes, windpipe, or blood vessels, potentially causing functional problems.[1]
Where Lymphatic Malformations Occur
These malformations can develop in many different body tissues, including skin, fat, connective tissue, joints, organs, and even bones. They can form anywhere in the body except the brain. The most common location is the head and neck area, though they may also appear in the chest, abdomen, arms, legs, and other regions.[1][2]
When lymphatic malformations occur in the abdomen, they are quite rare and account for less than five percent of all cases. Within the abdominal cavity, they can arise from solid organs like the pancreas, liver, or spleen, or from the mesentery, retroperitoneum, or gastrointestinal tract. Isolated occurrences in the small intestine mesentery are especially uncommon, representing less than one percent of all lymphangiomas.[7]
Types of Lymphatic Malformations
Healthcare providers classify lymphatic malformations based on the size of the abnormal lymphatic channels they contain. There are two main types, though many patients have a combination of both.[1][3]
Microcystic lymphatic malformations are spongy in texture and contain small vessels with tiny cysts. They often appear closer to the surface of the skin and may look like an area of swelling. These malformations frequently have small bubbles on the skin called vesicles or lymphatic blebs. These vesicles look like tiny blisters and typically contain clear lymphatic fluid. However, if blood leaks into them, they can turn dark red, purple, or even black, resembling blood blisters.[1][2]
Macrocystic lymphatic malformations, also historically called cystic hygromas or lymphangiomas, have large, stretched vessels and cysts filled with lymph, blood from internal bleeding, or both. These appear as large, soft masses and are often found deeper within tissues, particularly in the neck, face, armpits, or chest. The skin over these malformations may appear normal or have a blue color. In newborns, large macrocystic malformations in the neck can grow so large that they obstruct the baby’s airway at birth.[1][3]
Mixed lymphatic malformations contain both microcystic and macrocystic components. Neck region malformations, in particular, often contain this combination of small and large cysts.[3][4]
Epidemiology
Lymphatic malformations are considered rare conditions. Most are identified either at birth or during early childhood. The majority of cases become apparent before a child reaches the age of two years. However, some smaller malformations or those located inside the body may not be noticed until the teenage years or even early adulthood.[2][3]
Some research suggests that lymphatic malformations may be slightly more common in male children, though this is not definitively established. The condition appears to be more common in babies born to older mothers.[3][7]
When lymphatic malformations occur in multiple locations throughout the body, affecting bones and soft tissues, the condition is called lymphangiomatosis. This widespread involvement is less common than isolated malformations.[3]
Causes
Lymphatic malformations develop before birth, during fetal development. They form when problems occur in the formation and development of the lymphatic vessels during pregnancy. Scientists believe these malformations arise when developing lymph vessels fail to properly connect to the venous system during embryonic development.[2][7]
The lymphatic system develops from lymphatic endothelial cells on the side of certain veins during the sixth week of embryonic development. Between the twelfth and fourteenth weeks of gestation, lymph sacs normally join together to form a lymphatic network that expands and remodels into branched capillaries, vessels, and ducts. When these developing sacs fail to communicate properly with the rest of the lymphatic system, the lymphatic vessels dilate and form masses as lymph fluid accumulates.[7]
Risk Factors
While lymphatic malformations are not inherited conditions, certain factors may increase the likelihood of their occurrence. Babies with chromosomal disorders have a higher risk of developing these malformations. Approximately half of all babies born with macrocystic lymphatic malformations in the neck have an associated chromosomal disorder.[3]
Specific genetic conditions associated with a higher risk of lymphatic malformations include Down syndrome, Noonan syndrome, and Turner syndrome. These chromosomal variations affect how the body’s systems develop, including the lymphatic system.[3]
Advanced maternal age appears to be another risk factor, as lymphatic malformations are more commonly observed in babies born to older mothers. However, the exact relationship between maternal age and malformation risk is not fully understood.[3]
Symptoms
The symptoms of lymphatic malformations vary greatly depending on the size and location of the abnormal vessels. Many children experience no symptoms beyond the visible or palpable mass itself. Lymphatic malformations usually do not cause pain under normal circumstances and should not be itchy.[1][3]
The most common presentation is a growing, spongy-feeling lump or mass. This mass typically feels soft and smooth to the touch. While a child can have more than one lymphatic malformation, they usually occur in the same general area of the body.[1][2]
The skin over the malformation may have small vesicles that look like tiny blisters. These vesicles initially contain clear, colorless fluid, but can turn dark red, purple, or black if blood leaks into them. These skin bumps sometimes bleed from the surface, and when skin blisters rupture, they may leak bloody lymph fluid that does not clot like normal blood.[1][4]
Lymphatic malformations can suddenly increase in size due to bleeding or infection, causing rapid swelling and potentially pain. The malformations have a tendency to bleed internally with very mild trauma or sometimes even without any known injury.[1][2]
Many children with lymphatic malformations experience overgrowth or enlargement of the affected body part. This might involve the lips, tongue, jaws, cheeks, ears, arms, legs, fingers, or toes. This overgrowth occurs because the malformation affects the surrounding tissues.[1][2]
When lymphatic malformations affect specific body areas, they can cause location-specific symptoms. Malformations in the mouth or windpipe may cause feeding problems, speech issues, trouble swallowing, or difficulty breathing. Those affecting the chest can cause chest pain, shortness of breath, or wheezing. Malformations near the eyes may cause bulging eyes or double vision. When they affect bones, they may cause bone loss or abnormal bone overgrowth.[1][3]
Abdominal lymphatic malformations may present with abdominal pain, sometimes accompanied by a palpable abdominal mass that may be tender or non-tender. Some children experience symptoms suggesting an acute abdomen, including pain, distension, vomiting, constipation, or fever. These malformations can cause partial bowel obstruction, and in severe cases, complications such as bowel twisting, gastrointestinal obstruction, or bowel hemorrhage.[7]
Prevention
Because lymphatic malformations develop very early in pregnancy due to random developmental variations, there is no way to prevent their formation. The condition cannot be prevented through lifestyle changes, dietary modifications, or avoidance of specific exposures during pregnancy.[2]
However, some complications of lymphatic malformations can be prevented or minimized. Lymphatic malformations are prone to infection, particularly of the skin or soft tissues around them. These infections, called cellulitis, may occur frequently and can cause the malformation to swell and become tender or painful. Prompt identification and treatment of infections with antibiotics is important to prevent complications.[2][4]
Lymphatic malformations often swell when the body is fighting any infection, even infections not directly related to the malformation itself. Parents and caregivers should be aware that common childhood illnesses like colds or ear infections can trigger swelling episodes. Identifying and treating these infections promptly can help reduce the severity and frequency of swelling episodes.[5]
For children with diagnosed lymphatic malformations, careful monitoring and regular follow-up with healthcare providers can help detect potential complications early. Parents should be educated about signs of infection, including redness, warmth, pain, swelling, and drainage from the malformation site.[2]
Pathophysiology
The fundamental problem in lymphatic malformations involves the abnormal structure and function of lymphatic vessels. In the normal lymphatic system, thin tubes called lymphatic channels carry lymph fluid throughout the body. This fluid drains out of blood vessels in all body tissues and contains white blood cells called lymphocytes that help fight infection and disease. The lymphatic system collects this fluid from body tissues and returns it to the bloodstream, helping maintain proper fluid balance.[2]
In lymphatic malformations, the abnormal vessels are enlarged and misshapen, and they do not function correctly. The movement of lymphatic fluid through these malformed channels is slow or decreased. Because the fluid cannot drain properly, it accumulates and causes the lymphatic channels to enlarge further. This creates a cycle where fluid buildup leads to more stretching of the vessels, which in turn accommodates even more fluid accumulation.[2]
The malformed vessels typically exist as isolated structures separate from the normal lymphatic system. This separation means there is no effective drainage pathway for the trapped fluid. The accumulated lymph stretches the vessel walls and creates cysts, which are essentially pockets of fluid within the malformation.[1]
The walls of these abnormal vessels contain fragile, malformed veins that are prone to bleeding. Even minor trauma, or sometimes no trauma at all, can cause these vessels to rupture internally. When bleeding occurs, blood mixes with the lymph fluid inside the malformation. This internal bleeding adds volume to the malformation and causes further stretching of the cyst walls.[1][4]
The presence of blood within the malformation can change its appearance. When located close to the skin surface, blood-filled malformations may look bruised or discolored, appearing blue, purple, or black. The vesicles on the skin surface may also fill with blood, creating what look like blood blisters.[1][2]
As lymphatic malformations grow, they occupy more space and can compress or displace surrounding structures. When located near vital organs or structures, this pressure can interfere with normal function. For example, malformations near the windpipe can compress the airway and cause breathing difficulties. Those near the eyes can affect vision. Malformations in the chest can interfere with lung expansion or heart function.[1][3]
The immune system’s response to infection can also affect lymphatic malformations. When the body fights any infection, even one unrelated to the malformation, immune cells and fluid move through the lymphatic system. In malformations where drainage is already impaired, this increased fluid and cellular activity can cause acute swelling episodes. The malformation may become visibly larger, firmer, and sometimes painful during these episodes.[5]
In some cases, the malformation affects not only the lymphatic vessels but also the surrounding tissues. This can lead to overgrowth or enlargement of the affected body part. The exact mechanism of this overgrowth is not completely understood, but it appears related to the presence of abnormal lymphatic vessels affecting tissue development and growth patterns. This overgrowth may involve soft tissues, bones, or both, and can become more pronounced during childhood growth periods such as puberty.[4]
