How are fetuses with neck masses diagnosed and treated?
Fetal neck masses are generally of the following types:
- • Lymphangioma.
- • Hemangioma.
- • Cystic hygroma.
- • Teratoma.
Other masses (hemangioendothelioma, bronchogenic cyst, enlarged thyroid gland, and branchial cleft cyst) are uncommon.
Detection by US is straightforward, but characterization can be more problematic. Cystic hygromas and lymphangiomas can have a similar ultrasound appearance, although cystic hygromas are most often posterior and have a posterior midline septum. Lymphangiomas can be anterior or posterior in location, and color flow Doppler US may demonstrate some internal vascularity. Hemangiomas are usually more solid in appearance relative to lymphangiomas and can be anterior or posterior in location. Teratomas can be predominantly cystic but often are more mixed in appearance, and they may be almost entirely solid. Approximately 50% of teratomas have internal calcifications, which can help to differentiate a teratoma from a solid-appearing hemangioma.
A further division of fetal neck masses is based on anterior and posterior locations. The most important characteristic of a fetal neck mass is whether or not the mass is anterior in location. Anterior masses have the potential to obstruct or narrow the trachea and may also interfere with fetal swallowing, so this determines how these masses are treated.
Therapy for neck masses is surgical removal, although cystic hygromas usually regress spontaneously. If the fetus develops polyhydramnios because of interference with swallowing, amniocentesis for fluid reduction can be performed. For anteriorly located masses, if they obstruct the trachea, then EXIT is usually performed with the goal of establishing an airway.