A fetal neck mass is a condition in which there is an abnormal growth in the neck of the fetus. Many neck masses can be managed after the baby is delivered. However, giant neck masses can obstruct the airway or cause other complications in the developing baby.
C.S. Mott Children’s Hospital is home to one of the nation’s most comprehensive Fetal Diagnosis and Treatment Centers, with significant experience diagnosing and managing giant neck masses. Our team provides fetal diagnosis and counseling, individualized delivery planning, and fetal intervention when necessary. Our Vascular Anomalies Program provides a full spectrum of advanced postnatal treatment options.
What is a giant neck mass?
There are primarily two kinds of growths that are referred to as giant neck masses. The first is a teratoma. A teratoma is a rare mass made up of several different types of embryonic tissue. There are often solid and cystic components to the mass. When the mass is located in the neck of the fetus, it is referred to as a cervical teratoma. Cervical teratomas are rare, found once in every 20,000 births. The cause is unknown.
The second type of neck mass is called a lymphatic malformation (LM). This particular mass is sometimes referred to as a cystic hygroma or a cervical lymphangioma. A lymphatic malformation is an abnormal tangle of lymphatic vessels. Normally, lymphatic vessels carry fluid from the lymphatic tissue and they connect with the blood circulation. A lymphatic malformation contains small cysts (microcystic), large cysts (macrocystic), or a combination of both.
Both cervical teratomas and lymphatic malformation’s can cause a problem by compressing normal structures. For example, a giant neck mass can block the baby’s esophagus and affect the baby’s ability to swallow amniotic fluid. This can lead to an increase in the fluid level around the baby (polyhydramnios). Increased fluid can lead to preterm labor. Rarely, giant cervical teratomas have increased blood flow which can result in fetal heart failure (hydrops).
Diagnosis of fetal neck masses
These masses can be prenatally diagnosed using ultrasound. Ultrasound can assess the mass and the structures around it. A fetal MRI is essential to define the airway anatomy and the extent of the mass. If other abnormalities are detected, an amniocentesis may be offered.
A cervical teratoma may have a large blood supply. A Doppler study is a way to measure blood flow through large vessels. This can be done during the baby’s ultrasound. A fetal echocardiogram (heart ultrasound) is often recommended.
Management of pregnancy
Ultrasound is used to monitor the size of the mass, follow the baby’s growth, and evaluate the amount of amniotic fluid present. Increased amniotic fluid is common in 20 to 40% of these pregnancies. Additional prenatal testing is based on each individual mother and baby.
Fetal treatment of giant neck masses
A special delivery procedure called an EXIT (ex utero intrapartum therapy) is planned for those babies with a neck mass large enough to compromise the airway. This procedure was developed to provide a controlled delivery situation until there is a dependable airway. Some babies may need a tracheostomy (an airway through the neck) while others may be able to have a standard endotracheal tube inserted.
Delivery of a baby with a giant neck mass
Unless there is a special birth plan, a vaginal delivery is recommended and a cesarean section is reserved for obstetric reasons.
Airway management at birth is critical with any giant neck mass. Delivery should be planned at a hospital that is prepared for high-risk deliveries and experienced treating infants born with neck masses.
University of Michigan is one of only a few centers nationwide at which the birth center is co-located within a comprehensive children’s hospital. This unique setting allows for seamless integration between our private-room birth center, state-of-the-art newborn intensive care unit (NICU), and access to around-the-clock pediatric surgical services in one convenient location.
Treatment of neck masses after birth
After delivery, the baby will be admitted to the newborn intensive care unit (NICU) for continuing care.
A cervical teratoma can be removed after the baby has been stabilized. The pediatric surgery team will discuss the timing of the operation with you after the initial assessment.
A teratoma is often a non-threatening mass, but there is a small possibility of disease. A teratoma can have many different cell types. For this reason, all specimens are sent to the lab for examination. Cells from various tissues and glands may be found in the mass. A teratoma with immature cells presents a small risk of recurrence. Immature cells produce a protein called alpha-fetoprotein (AFP) which can be monitored with a blood test. AFP levels in the blood are used as a screening tool to check for tumor regrowth, in addition to regular check-ups and imaging.
The treatment of a giant lymphatic malformation is dependent on its features. Those masses with mostly small cysts (microcystic) often need surgical removal. Those lymphatic malformations with large cysts (macrocystic) may be treated with sclerotherapy. It may require several treatments to improve.
If the baby needs a tracheostomy to help with breathing, it may be in place for several months or more during the recovery period. Some of these babies may have trouble swallowing after the mass is removed. A feeding specialist is available in the NICU to work with your baby if problems arise.
Future pregnancy risk
The risk of a giant neck mass in a future pregnancy is extremely low. Your doctor and a genetic counselor will review your risk with you.
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