Primary and secondary lymphedema in children is relatively rare, but carries with it the significant and lifelong burden of having to manage chronic swelling and prevent secondary complications. Here I describe pediatric lymphedema (also called ‘paediatric lymphoedema’), and the special considerations for diagnosis, ongoing monitoring, treatment, and complications.
The majority of patients with lymphedema experience the same basic symptoms, and are managed using the same basic strategy. This is true regardless of whether they are an adult, child or infant. It is also true irrespective of whether they have primary lymphedema arising from a developmental abnormality, or secondary lymphedema acquired due to lymphatic damage (often cancer-related).
Although lymphedema symptoms and management strategies are broadly similar between patients, pediatric lymphedema does present some unique challenges and considerations.
The diagnosis and monitoring of pediatric lymphedema can be more difficult, novel complications can arise, and modifications for ongoing monitoring, treatment and self-management are required.
This brief guide is meant to provide caregivers with an overview of what current research and best practice tells us about the characteristics, diagnosis, and treatment of lymphedema in children (from infants to teenagers). I will also highlight how lymphedema in children differs from adult lymphedema.
What is Pediatric Lymphedema?
Lymphedema in children falls into two broad categories: (1) primary pediatric lymphedema, and (2) secondary pediatric lymphedema. The former is an abnormality that a patient is born with, while the latter is acquired due to an event or injury that resulted in lymphatic damage.
Type 1: Pediatric Primary Lymphedema
Primary lymphedema is a chronic swelling condition caused by an abnormal development of the lymphatic system in an area of the body. The prevalence of primary lymphedema in people under 20 is commonly reported as 1.15 per 100,000 people (ref1), but the methodology used to come up with this number is rather questionable (ref2) and it is likely to be significantly higher (ref3), perhaps even as high as 1 in 6000 (ref4).
The extent of lymphatic malformation varies between individuals, as does the area of the body affected. As a result, some patients are born with visible symptoms, while others develop swelling only later in childhood or adolescence. Others still will first develop symptoms of lymphedema as an adult, usually after some aggravating lymphatic event such as weight gain, injury or infection.
I) How does pediatric primary lymphedema occur?
The lymphatic system is comprised of lymphatic vessels and lymph nodes that normally act to clear excess fluid called ‘lymph’ from tissues of the body, recycling it back into the bloodstream. Along with the cardiovascular system (your arteries and veins), the lymphatic system is responsible for maintaining a normal fluid balance, clearing cellular waste, and participating in immune surveillance.
If the lymphatic system fails to function properly, lymph fluid will accumulate in the affected area, and swelling will result. The stagnant lymph fluid will also cause local immune system suppression and therefore increase the risk of infection.
If lymphedema is left unchecked, a patient will naturally progress through the stages of lymphedema (see more on the stages in Table 1). This process culminates in substantial swelling and permanent tissue changes to the affected area including fibrosis (scar formation) and adipose deposition (fat accumulation). See our post: “Untreated lymphatic swelling promotes weight gain by altering stem cell behaviour”.
Congenital lymphatic abnormalities that create primary lymphedema include:
- A decrease in the number of lymphatic vessels or lymph nodes.
- Changes in the size of lymphatic vessels or lymph nodes (either too big or too small).
- Poorly formed lymphatic vessels or lymph nodes.
II) When does pediatric primary lymphedema begin to show symptoms?
This varies. In some cases, swelling caused by primary lymphedema can be seen by ultrasound in utero during the third trimester of pregnancy (ref5).
Looking at the data from recent clinical studies, it appears that about one-third to one-half of children with pediatric primary lymphedema are born with symptoms or develop them as an infant (ages 0-1) (ref3,5,6). A smaller proportion of children appear to first develop symptoms during childhood (ages 1-8 in girls and 1-9 in boys), and the sizable remainder during adolescence (ages 9-21 in girls and 10-21 in boys).
But these numbers mask an apparent gender difference. The majority of boys with lymphedema have been found to be born with it or develop it in infancy, while the majority of girls develop it in early adolescence (around 10-12 years old) (ref5,6).
The timing, area affected, and extent of swelling depends on the location and degree of lymphatic malformation, which varies person to person. It may only initiate in a child or teenager after a growth spurt, while other patients with primary lymphedema only develop symptoms later in life as an adult.
III) How did my child get primary lymphedema?
Primary lymphedema is the result of abnormalities in the lymphatic system likely caused by one or more genetic mutations. But the exact underlying cause of the condition is unclear. Since a wide selection of genes have been potentially implicated in the development of primary lymphedema (ref5), the underlying reason for its appearance could differ between patients.
A genetic mutation implicated in primary lymphedema may be inherited from a parent, thereby predisposing them to getting the condition, or it may arise sporadically in the patient (occurring by chance rather than inherited). Primary lymphedema could also be just one symptom of a larger inherited genetic disorder.
Recent evidence suggests that possibly as many as one-quarter of pediatric primary lymphedema patients inherited their condition. In three recent independent studies of pediatric primary lymphedema, 12-27% of patients were found to have a family history of the disease, or found to suffer from an inherited genetic disorder that can include lymphedema as a symptom (ref3,5,6). Some of these inherited disorders are listed below.
- Gorham disease
- Hennekam syndrome
- Klippel Trenaunay Weber syndrome
- Lymphedema-distichiasis syndrome
- Meige disease
- Milroy’s disease
- Noonan syndrome
- Triple-X syndrome
- Turner’s syndrome
V) How similar is my child’s experience of primary lymphedema to that of other children?
How does primary lymphedema usually present in children? Is my child’s lymphedema ‘typical’? Below is a breakdown of how primary lymphedema in children typically manifests:
- Girls appear to get primary pediatric lymphedema more frequently than boys (58-70% of patients in three recent studies were female (ref3,5,6).
- Girls usually first exhibit symptoms during early adolescence, rather than being born with it or developing it as an infant, which is the more common pattern seen in boys (ref5,6).
- Primary lymphedema in children tends to occur in specific areas of the body, but at different frequencies (data compiled from ref3,5,6 unless otherwise noted):
- Limbs. Primary lymphedema usually involves a limb (88-96% of the time), sometimes the arms (8-12%), but most frequently in one or both legs (92-97% ref3,6). About half the time if lymphedema is present in one arm or leg, it will also be present in the other. Lymphedema of the leg can affect the foot only, the foot and calf, the thigh only, or the whole leg.
- Genitalia. Genitalia is another frequent site of lymphedema (6-14%), although it usually occurs in combination with leg lymphedema. The vulva, scrotum, penis and testicles can be affected.
- Other sites. Total body lymphedema has been reported, but very rarely (0.5%). Primary lymphedema has also been reported in the torso (8%) and the face (5%) (ref3).
- Lymphedema in infants does not progress differently nor have a worse prognosis than lymphedema that develops later in life (ref6).
VI) Triggers of swelling onset in children with primary lymphedema
For a child with primary lymphedema, initial onset may have no apparent triggering event. As a result, the swelling is discovered by chance and is not accompanied by any other symptoms, nor is it painful. In such cases, it is likely that lymphatic function has been suboptimal for some time, but not enough to be symptomatic.
Triggers for the initial onset of primary lymphedema in children include events that cause local swelling:
- Minor trauma, such as a sprained ankle. Children with primary lymphedema have a reduced capacity to remove lymph fluid. This reduced capacity may only be revealed after a minor injury that causes acute inflammation and swelling, which in turn overloads the lymphatic system with fluid. The result is swelling that does not subside normally, thereby initiating lymphedema symptoms. Minor trauma could also initiate lymphedema by temporarily damaging functioning lymphatic vessels themselves, thereby overloading the already sub-optimal lymphatic system.
- Medical procedures. Much like minor trauma, minor surgery can cause swelling and inflammation, and thereby initiate the symptoms of lymphedema. For example, this could include circumcision in the case of genital lymphedema.
- Insect bites cause local swelling and inflammation, and could, therefore, initiate lymphedema symptoms.
- Infection in the area of the body with reduced lymphatic capacity can initiate primary lymphedema. Even before symptoms of primary lymphedema are apparent, decreased lymphatic capacity may be contributing to suppressed immune function, thus predisposing the area to infection.
- Sedentary periods. Immobility for a prolonged period of time, such as during an aeroplane flight, can cause swelling in the legs. In patients with asymptomatic primary lymphedema, this swelling might overwhelm a child’s already reduced lymphatic functional capacity, thereby initiating lymphedema symptoms.