What are cystic hygromas?

Cystic hygromas are abnormal growths that usually appear on a baby’s neck or head. They consist of one or more cysts and tend to grow larger over time. This disorder most often develops while the baby is still in the womb. However, a cystic hygroma can also appear after birth.

Cystic hygromas are fluid-filled sacs caused by blockages in the lymphatic system. This system is a network of organs and tissues that helps move fluids through the body and transport white blood cells. The sacs usually form between the 9th and 16th week of pregnancy.

Approximately half of all fetuses with a cystic hygroma have chromosomal abnormalities. Chromosomes are the cells that house our DNA, and when large segments of them are missing or damaged, serious medical complications can occur. However, your baby is less likely to have a chromosomal abnormality if the cystic hygroma goes away by week 20.

Cystic hygromas can also increase the risk of miscarriage and may even be life-threatening. Doctors recommend that you schedule your delivery in a major medical center if a hygroma is detected during pregnancy.

What causes cystic hygromas to form?

Cystic hygromas can develop due to genetic disorders or environmental factors. One or more growths may be present at the time of diagnosis.

Common environmental causes of cystic hygromas are:

Cystic hygromas are seen more often in infants with genetic diseases. They are particularly common in infants with chromosomal abnormalities. Some genetic conditions associated with hygromas include:

  • Turner’s syndrome, in which female children have one X chromosome instead of two
  • Trisomy 13, 18, or 21, conditions where children have an extra copy of a chromosome
  • Noonan syndrome, a disorder caused by a change (mutation) in one of seven particular genes

What are the symptoms of cystic hygromas?

Cystic hygromas that develop after birth may not be noticeable when the baby is born. They can become visible as they grow larger and the child gets older. Cystic hygromas will usually appear by the time the child is 2 years old.

The main symptom of a cystic hygroma is the presence of a soft, spongy lump. This lump most commonly appears on the neck. However, a cystic hygroma can also form in the armpits and groin area.

Cystic hygromas range in size from smaller than a quarter to as large as a baseball. Larger growths may interfere with movement or cause other difficulties.

Diagnosing cystic hygromas

Your doctor will order an amniocentesis if they notice a cystic hygroma during an ultrasound. An amniocentesis can check for genetic abnormalities in your fetus.

During this test, you’ll lie on an exam table while your doctor cleans your belly with an iodine solution. Using ultrasound as a guide, your doctor will then use a needle to take a sample of fluid from the amniotic sac.

Other tests will be used to make a diagnosis if cystic hygromas aren’t found until after the child is born. These include:

Treating cystic hygromas

Cystic hygromas aren’t treated while the baby is in the womb. Instead, your doctor will closely monitor your baby’s health. Cystic hygromas found early in pregnancy sometimes go away before birth. You’ll likely need to schedule your delivery at a major medical center in case there are complications at the time of birth.

A cystic hygroma is usually treatable if it’s present at birth or develops later. The first step of treatment is surgery. The entire growth must be removed to prevent it from coming back.

In some cases, however, your doctor may not want to remove large cystic hygromas. These growths usually aren’t cancerous, so doctors won’t want to get rid of them if there’s a risk of damaging any healthy tissue. Instead, other techniques may be used to shrink large cystic hygromas:

These methods aren’t very effective in treating small cystic hygromas, but they may be useful in shrinking large growths. Once the growth is small enough, it’s easier to remove surgically.

You should never try to puncture or drain a cystic hygroma yourself. It may cause severe bleeding and lead to an infection.

Long-term outlook for babies with cystic hygromas

The main potential complications of cystic hygromas are:

  • recurring growths
  • bleeding
  • infection in the affected area
  • damage to muscles, nerves, or tissues from surgery to remove the hygroma

However, the outlook for babies with cystic hygromas is generally good if the growths appear after birth. This is especially true if the growths can be completely removed. If they can’t be removed, cystic hygromas may return or spread to other areas.