The microcystic type consists of cysts that are less than two centimeters while the macrocystic type consists of cysts larger than two centimeters.
Since the lymphatic system fails to form properly, there are blockages in the lymphatic network and fluid filled sacs form usually between the ninth to 16th week of pregnancy.
Cystic hygromas affect approximately 1 per 6000 live births and can affect children of any race and both boys and girls equally.
What are the Causes of Cystic Hygroma?
The exact cause of cystic hygroma remains unclear. They can develop due to genetic disorders or environmental influences. One or more growths may be noted at the time of diagnosis.
Common environmental causes of cystic hygromas include
- Viral infections transmitted during pregnancy from the mother to the baby
- Ingestion of drugs or alcohol during pregnancy
Notably, cystic hygromas are seen more often in infants with genetic conditions. They are especially seen in infants with chromosomal abnormalities. Some of the conditions associated with cystic hygromas include
- Trisomy 13, 18, or 21, (conditions due to chromosomal defects), where children are born with an extra copy of a chromosome
- Turners syndrome, in which girls are born with one X chromosome instead of two
- Noonan syndrome, a disorder caused by a mutation in one of seven specific genes
What are the Symptoms and Signs of Cystic Hygroma?
- Many cystic hygromas are present at birth or in early infancy, with almost all being diagnosed before the child is two years old.
- Some cystic hygromas that develop after birth may not be evident when the baby is born. They may become visible as they enlarge in size (with increasing fluid) and as the child gets older
- The main symptom is the presence of a soft, spongy and translucent swelling. This lump most commonly appears on the neck but can also develop in the armpits and groin region
- Clusters of small clear, black, or red vesicles (tiny fluid filled lesions) on the tongue or buccal mucosa (microcystic type)
- Larger cysts with overlying normal-appearing or bluish skin (macrocystic form)
- Cystic hygromas may vary in size from smaller than a penny coin to as large as a baseball. Large cystic hygromas may affect movement or cause other pressure related symptoms.
- Large neck swellings may interfere with breathing, sleep apnea episodes, feeding difficulties and failure to thrive (due to poor feeding)
- Deformation of adjacent bone and teeth due to pressure effects
- Rarely bleeding into the sac
How do you Diagnose Cystic Hygroma?
- Occasionally a cystic hygroma in the fetus may be picked up during maternal ultrasound during pregnancy. The doctor may then recommend an amniocentesis test to rule out fetal genetic abnormalities.
- During amniocentesis, a sample of amniotic fluid is obtained by introducing a needle via the pregnant abdomen into the uterus under ultrasound guidance. The amniotic fluid is then tested for genetic abnormalities
This refers to diagnosis after the baby is born.
- Some children have visible lesions which enable readily making a diagnosis on physical examination
- In children where the swelling is not readily visible, or thought to compress other structures, these can be demonstrated with imaging investigations such as MRI scan, CT scan, ultrasound, and occasionally even with x-rays
- Other specialized studies such as airway fluoroscopy and lymphoscintigraphy (to outline the lymph network by radiographic imaging) have been occasionally used.
- Rarely endoscopic biopsy to remove a sample of the swelling has been performed for confirmation of diagnosis
How do you Treat Cystic Hygroma?
Prenatal Cystic Hygromas
Cystic hygromas diagnosed when the baby is in the womb are not treated. Instead the doctor will closely monitor the babys health. There is an increased risk of miscarriage and intrauterine fetal death. Sometimes prenatal cystic hygromas disappear before birth. If there is spontaneous disappearance of the cystic hygroma by 20 weeks of pregnancy, the chances of chromosomal abnormalities are less.
It is advisable to schedule the delivery in a specialist center to avoid complications during birth
Postnatal Cystic Hygromas
- In babies with no symptoms due to the swelling, the doctors may adopt a watch and wait approach
- In babies with symptomatic swelling, surgical removal of the swelling under general anesthesia is performed. The entire swelling should be excised to prevent future recurrences. Surgery requires hospital stay for a few days.
- In larger lesions, sclerotherapy using chemicals to scar or shrink the growth is another method. Once the growth becomes smaller, it may be surgically excised. If the growth recurs, multiple sclerotherapy sessions may be necessary. The procedure is performed by an interventional radiologist under general anesthesia. It may be done as a day procedure.
- Other treatment modalities such as radiofrequency ablation, laser induced thermotherapy, chemotherapy and steroid medications have also been employed to shrink the lesion
One should not puncture the cyst or drain the swelling without medical supervision. It can lead to severe bleeding or infection.
Complications of Various Treatments
- Bleeding and infection can occur during any invasive procedure
- Surgery – complications related to anesthesia, damage to nerve, muscle or other tissues during surgery
- Sclerotherapy – Allergic reactions to injected chemical, recurrence, scar formation
What is the Prognosis of Cystic Hygroma?
The outlook of cystic hygromas is highly variable and can range from good to poor.
The prognosis is favorable if the growth is completely excised. However, if the entire cystic hygroma tissue is not removed, there is a 15% chance of recurrence.
Longterm outlook is less favorable when the cystic hygroma occurs in fetuses and in children with excessive neck thickening. Also, if the fetus also has associated genetic abnormalities the prognosis is poorer.