Cystic Hygroma: What It Is, Symptoms, Causes, Diagnosis, Treatment and Outlook — What You Need to Know
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026
Quick answer
A cystic hygroma is a benign, fluid-filled sac that most often forms on a newborn's neck when the lymphatic system is damaged or blocked during fetal development. It ranges in size from a grape to a grapefruit and can be life-threatening if it affects breathing or appears during pregnancy, where it raises the risk of miscarriage or stillbirth. Treatment, which may include surgery, drainage, sclerotherapy, laser therapy, or radiofrequency ablation, aims to remove the cyst. Early diagnosis and treatment lead to the best outcomes.
TL;DR
Cystic hygromas are rare, accounting for only 6% of benign tumors in early childhood, and usually appear at birth on the neck as a soft, sometimes blue-tinted bulge. The exact cause is unknown but may involve genetic changes or environmental factors such as smoking or alcohol during pregnancy. Treatment is individualized; if all abnormal tissue cannot be removed, there is roughly a 15% chance of recurrence.
Limitation statement: the only numerical data in the underlying clinical source are the 6% share of benign childhood tumors and the 15% recurrence figure; no other statistics exist in the source and none are presented elsewhere in this article.
EMERGENCY GUIDANCE: If your child has trouble breathing, call 911 or visit the emergency room immediately. A large cystic hygroma can obstruct the airway. Difficulty breathing is a medical emergency.
What is a cystic hygroma?
A cystic hygroma is a fluid-filled sac (cyst) that forms most often on your baby's neck. It develops due to a malformation or blockage of the lymphatic system.
The lymphatic system is a group of tissues and organs that move lymph fluid (a watery fluid full of white blood cells) through your bloodstream and circulatory system to remove waste and toxins. When this system is damaged, lymph fluid collects under the skin instead of flowing through your bloodstream, causing a bulge or sac-like growth.
Cystic hygromas are benign tumors. They are not cancerous. They can appear during pregnancy on an ultrasound or after your baby is born as a bump or bulge under their skin.
How common is cystic hygroma?
Cystic hygromas are rare. They account for only 6% of all non-cancerous (benign) tumors during early childhood, and adult cystic hygromas are extremely rare.
Quick fact | Detail |
Condition type | Benign (non-cancerous) fluid-filled tumor |
Most common location | The neck of a newborn |
Typical size range | From a grape to a grapefruit |
Early childhood tumor share | ~6% of benign tumors |
Adult cases | Extremely rare |
Recurrence risk if tissue not fully removed | ~15% |
When to act | Call 911 immediately if your child has trouble breathing |
What are the symptoms of cystic hygroma?
Symptoms of a cystic hygroma vary based on the size and location of the fluid-filled sac. A cystic hygroma could affect any baby, since it may be the result of a genetic change that affects how the lymphatic system forms during fetal development.
Symptoms could include a bulge under the skin, skin over the cyst with a blue tint, a soft cyst, and growth in size as the baby grows. The cyst most often appears on the neck, but it can form anywhere on the body.
What are the severe symptoms of cystic hygroma?
Severe symptoms of a cystic hygroma can physically disfigure part of the body or cause bone or organ damage. They may also cause feeding difficulties, difficulty breathing (airway obstruction), hemorrhage, or infection.
How serious is a cystic hygroma during pregnancy?
If a cystic hygroma is present during pregnancy, there is a risk of miscarriage or stillbirth. This happens due to complications from the cyst affecting how the fetus develops and grows.
The cyst could create an excess amount of fluid in the fetus' body, a condition called hydrops, which could cause early death. Your healthcare provider will monitor the progress of your developing fetus to make sure it is healthy during your pregnancy.
If you're at risk of having a miscarriage or your baby is stillborn, your provider can offer resources or guidance to help you cope with a loss.
What causes a cystic hygroma?
The exact cause of a cystic hygroma is unknown. The cyst forms as a result of damage to the lymphatic system during fetal development, or as a result of physical trauma or respiratory infection in cases that affect adults.
Often, cystic hygromas form on their own, but some form in combination with genetic conditions like Down syndrome, Turner syndrome, or Noonan syndrome. To understand how chromosome errors relate to conditions like Down syndrome and to miscarriage, see our guide on the chromosome counting error behind most miscarriages and conditions like Down syndrome.
Studies suggest two main explanations:
Possible cause | Explanation |
Environmental factors | Studies suggest smoking or drinking alcohol during pregnancy could contribute |
Genetic changes | Studies suggest genetic changes or mutations affecting lymphatic system development cause cystic hygromas |
How is a cystic hygroma diagnosed?
Diagnosis of a cystic hygroma occurs before your child reaches two years old.
During pregnancy, a cystic hygroma diagnosis is possible with a routine prenatal ultrasound. A blood test to detect alpha-fetoprotein between 15 to 20 weeks helps confirm the diagnosis.
If prenatal tests suggest that your child has an abnormal number of chromosomes, your child may have a predisposition to cystic hygromas and your provider will carefully monitor the development of your fetus.
After your baby is born, a physical examination of the cyst, along with an X-ray, ultrasound, or an MRI, will help your provider confirm the diagnosis and offer a treatment plan unique to your child's condition.
How is a cystic hygroma treated?
Treatment is unique for each child diagnosed with a cystic hygroma. Your provider's goal is to remove the cyst, if possible.
Treatment option | What it does |
Surgery | Removes the cyst |
Percutaneous drainage | Drains fluid from the cyst |
Sclerotherapy | Reroutes the cyst's fluid through the body |
Laser therapy | Removes the cyst with a laser |
Radiofrequency ablation | Shrinks the size of the cyst |
In some cases, no treatment is necessary because the cyst could go away on its own. In other cases, the cyst could return after treatment if there is damage to the lymphatic system. The success of treatment varies and is most often positive if your surgeon can remove all of the excess and abnormal tissue from the cyst.
There is a possibility of scarring after surgical treatment, which depends on the size and location of the cyst. Less-invasive treatment options like laser therapy produce less scarring.
How do I care for the cyst after treatment?
Treat your child's cyst like a wound, especially if your child is healing from surgery. There is a risk of infection with any treatment, so monitor the cystic hygroma and make sure it isn't leaking clear or yellow pus, changing color or size, or is warm or tender to the touch. Contact your provider if you suspect your child has an infection.
What is the prognosis for cystic hygroma?
The prognosis depends on when your provider diagnoses the cystic hygroma, whether the cyst is the result of an underlying condition, and the location and size of the cyst.
Surgery to remove the cyst leads to a good prognosis if your surgeon can safely remove excess tissue within the cyst. If your surgeon is unable to safely remove the excess tissue surrounding the cyst, there is a 15% chance that the cyst could return.
Early diagnosis and treatment lead to the best outcome and reduce your child's risk of developing complications from the cyst, like organ damage and cosmetic abnormalities.
There is an increased risk of miscarriage and stillbirth in cystic hygroma cases that form in combination with chromosome abnormalities like Down syndrome.
Can cystic hygroma be prevented?
It's difficult to prevent a cystic hygroma since the cause is unknown. However, you can take steps to make sure your developing child is healthy:
Prevention step | Why it helps |
Genetic test before pregnancy | Understand your risk of having a child with a genetic condition, in consultation with your provider |
Don't smoke during pregnancy | Studies link smoking during pregnancy to cystic hygromas |
Don't drink alcohol during pregnancy | Studies link alcohol during pregnancy to cystic hygromas |
Attend regular prenatal checkups | Monitor the health of your developing fetus |
Eat a well-balanced diet | Support overall health for you and your developing child |
When should I contact my healthcare provider?
Visit your healthcare provider if you notice your child's cyst increases in size, changes color, leaks a yellow or clear fluid, is red, tender, or warm to the touch, causes pain and discomfort, or prevents your child from eating.
EMERGENCY: Call 911 now. If your child has trouble breathing, call 911 or visit the emergency room immediately. A cystic hygroma can obstruct the airway, and breathing difficulty is a life-threatening emergency.
Good questions to ask your provider include: Does my child need surgery to remove their cyst? Did the cyst cause any organ, bone, or nerve damage? What are the side effects of the treatment you suggest?
Conclusion: early diagnosis makes the difference
Cystic hygroma is a rare, benign, fluid-filled tumor that most often appears on a newborn's neck. While the exact cause is unknown and the condition can be frightening, particularly when found during pregnancy or when it interferes with breathing, treatment is highly individualized and outcomes are best when diagnosis happens early.
Five treatment paths exist, from surgery to laser therapy, and in some cases the cyst resolves without intervention. The most important steps for parents are: monitor the cyst for signs of infection, watch for airway obstruction, keep every follow-up appointment, and call 911 immediately if your child has trouble breathing.
Your next step: If your baby has been diagnosed with a cystic hygroma, or if you've noticed a growing, soft, blue-tinted bulge on your newborn's neck, schedule an evaluation with your child's healthcare provider. If you're planning a pregnancy and are concerned about genetic risks, ask your provider about genetic testing.
Frequently asked questions
What is a cystic hygroma in simple terms? A cystic hygroma is a benign, fluid-filled sac that forms most often on a newborn's neck due to a malformation or blockage of the lymphatic system. It is not cancerous.
Is cystic hygroma a tumor? Yes, it is classified as a benign (non-cancerous) tumor that appears as a fluid-filled sac.
Where does cystic hygroma appear? It most often appears on the neck, but it can form anywhere on the body.
What does a cystic hygroma look like? It appears as a bulge under the skin that is soft to the touch, sometimes with a blue tint. Size ranges from a grape to a grapefruit and can increase as the baby grows.
How common is cystic hygroma? Cystic hygromas are rare, accounting for only 6% of all benign tumors during early childhood. Adult cases are extremely rare.
What causes a cystic hygroma? The exact cause is unknown. It forms from damage to the lymphatic system during fetal development, or from physical trauma or respiratory infection in adult cases. Studies suggest environmental factors (smoking or alcohol during pregnancy) or genetic changes may be responsible.
Is cystic hygroma genetic? It may be the result of a genetic change that affects how the lymphatic system forms during fetal development. It can also occur in combination with genetic conditions like Down syndrome, Turner syndrome, or Noonan syndrome.
Is cystic hygroma associated with Down syndrome? Yes. Cystic hygromas can form in combination with genetic conditions including Down syndrome, Turner syndrome, and Noonan syndrome, and cases combined with chromosome abnormalities carry an increased risk of miscarriage and stillbirth.
Can cystic hygroma be detected during pregnancy? Yes. It can be detected during pregnancy on a routine prenatal ultrasound, and an alpha-fetoprotein blood test between 15 to 20 weeks helps confirm the diagnosis.
What is hydrops in cystic hygroma? The cyst could create an excess amount of fluid in the fetus' body (hydrops), which could cause early death.
Does cystic hygroma cause miscarriage or stillbirth? If present during pregnancy, there is a risk of miscarriage or stillbirth due to complications affecting how the fetus develops and grows.
When is cystic hygroma diagnosed? Diagnosis occurs before the child reaches two years old, through prenatal ultrasound, blood testing, or after birth via physical exam plus X-ray, ultrasound, or MRI.
How is cystic hygroma diagnosed after birth? A physical examination of the cyst, along with an X-ray, ultrasound, or MRI, helps the provider confirm the diagnosis and plan treatment.
How is a cystic hygroma treated? Treatment is unique per child and may include surgery, percutaneous drainage, sclerotherapy, laser therapy, or radiofrequency ablation. In some cases no treatment is needed, as the cyst could go away on its own.
What is sclerotherapy for cystic hygroma? Sclerotherapy is a treatment that reroutes the cyst's fluid through the body.
What is the best treatment for cystic hygroma? Treatment success is most often positive if the surgeon can remove all of the excess and abnormal tissue from the cyst. The best option depends on the individual child's condition.
Will the cystic hygroma come back? It could return after treatment if there is damage to the lymphatic system. If the surgeon cannot safely remove all excess tissue, there is a 15% chance the cyst could return.
Does cystic hygroma treatment cause scarring? There is a possibility of scarring after surgical treatment, depending on the cyst's size and location. Less-invasive options like laser therapy produce less scarring.
Can a cystic hygroma go away on its own? Yes, in some cases no treatment is necessary because the cyst could go away on its own.
Can cystic hygroma affect breathing? Yes. Severe symptoms can include difficulty breathing due to airway obstruction, a life-threatening situation that requires calling 911 or going to the emergency room immediately.
What should I watch for after treatment? Treat the cyst like a wound and monitor for infection: leaking clear or yellow pus, color or size changes, warmth, or tenderness. Contact your provider if you suspect infection.
Can cystic hygroma be prevented? It's difficult to prevent since the cause is unknown, but you can reduce risks by not smoking or drinking alcohol during pregnancy, attending regular prenatal checkups, eating a well-balanced diet, and considering genetic testing before pregnancy.
Is cystic hygroma dangerous? Cystic hygromas can be life-threatening, especially when they obstruct the airway or appear during pregnancy with associated chromosomal abnormalities. However, early diagnosis and treatment reduce the risk of serious complications like organ damage.
What questions should I ask my provider about cystic hygroma? Ask whether your child needs surgery, whether the cyst caused organ, bone, or nerve damage, and what the side effects of the suggested treatment are.
Does my newborn with cystic hygroma need surgery? Treatment is unique for each child. Your provider's goal is to remove the cyst if possible, using the option (surgery, drainage, sclerotherapy, laser therapy, or radiofrequency ablation) that best fits your child's condition.
External references
Medical disclaimer: This article is for general educational purposes only and does not constitute medical advice. It is based on a single referenced clinical source and should not replace professional diagnosis or treatment. If your child has a cystic hygroma or any new lump, please consult a qualified healthcare provider. If your child has trouble breathing, call 911 or go to the nearest emergency room immediately.
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