Dr. Kan is a Diagnostic Radiology resident at the
University of Chicago Hospitals, Chicago, IL.
Congenital pediatric neck masses can be classified based on
location and radiographic characteristics. In general, thyroglossal
duct cysts, branchial cleft cysts, ranulas, lymphatic
malformations, and dermoids tend to be cystic in nature; while
hemangiomas, teratomas, and fibromatosis colli have heterogeneous
morphology with solid and possible cystic components.
Teratomas and hemangiomas present anywhere within the neck.
Fibromatosis colli is a solid mass exclusively found within the
Thyroglossal duct cysts and dermoids are usually located
anterior and midline or paramedian within the anterior cervical
triangle. Branchial cleft cysts and ranulas are also found in the
anterior cervical triangle but are more lateral in location than
thyroglossal duct cysts. Lymphatic malformations are usually found
in the posterior cervical triangle.
This article will classify congenital neck masses on the basis
of radiographic characteristics and will review presentation,
embryology, imaging characteristics, and management.
Cystic neck masses
Thyroglossal duct cyst
For all etiologies for childhood neck masses, the incidence of
thyroglossal duct cysts is second only to infectious
Among the congenital neck masses, they are the most common (70%).
This disorder is the result of abnormal migration of the
embryologic thyroid tissue from the foramen cecum located at the
base of the tongue to its expected midanterior neck location.
It usually presents as an asymptomatic or an infected midline or
paramedian neck mass that moves cephalad with swallowing or tongue
extension. Thyroglossal duct cysts present as a simple cyst with an
associated connecting duct that can be demonstrated by either
computed tomography (CT) or ultrasound (US) (figures 1 and 2). If
infected, the US and CT presentations are variable. US may show
punctate echogenities representing infectious debris within the
lesion and potential irregular and unsharp posterior shadowing that
represents subcutaneous emphysema (figure 3). The internal
structure of the infected cyst may become complex with fluid-fluid
levels, septations, and a thickened wall, which can represent
hemorrhage, pus, and scarring. A loss of normal soft tissue planes,
as well as subcutaneous fat stranding, is visible on CT.
Preoperative neck US and/or Tc-99m pertechnetate imaging is
recommended to evaluate the thyroid gland, possible ectopic thyroid
tissue, and additional cysts along the location of the thyroglossal
duct tract. Approximately 80% of thyroglossal duct cysts are
located at or slightly below the level of the hyoid bone.
To prevent possible future development of ectopic papillary thyroid
carcinoma and a nidus for neck infections, surgical removal
includes complete excision of the cyst, associated duct, the core
of the tongue base, the central hyoid body, as well as possible
intra-ductal thyroid tissue.
Although rare, squamous cell carcinoma developing within the
thyroglossal duct cyst has also been reported.
Branchial cleft cysts
Branchial cleft cysts result from maldevelopment of the
embryonic branchial arches. Branchial clefts are the external
interposed spaces with respect to the embryonic branchial arches.
There are initially four clefts. Normally, the second through
fourth clefts are rudimentary and are absorbed by the adjacent
branchial arches. The first branchial cleft eventually develops
into the external auditory meatus.
Seconds are the most common, and first branchial cleft cysts are
the next most frequent. Third and fourth branchial cleft cysts are
First branchial cleft cysts are identified clinically in the
preauricular region with or without an external sinus tract.
Since the first branchial cleft normally leads to development of
the external auditory meatus, predictable anomalies may be seen in
the external auditory meatus, eustacian tube, tympanic cavity, and
mastoid air cells. Other associated lesions include middle ear
ossicle maldevelopment leading to sensori-neural hearing loss.
Aural atresia, cleft palate, and microtia can also occur.
Conditions to consider when microtia is seen include, but are not
limited to, Treacher-Collins syndrome, Goldenhar's syndrome, and
Second branchial cleft cysts are usually located along the
anterior border of the sternocleidomastoid muscle within the
lateral aspect of the anterior cervical triangle.
These cysts may have a deep or external fistulous tract. The
associated structural anomalies predictably are associated with
second and third branchial arch structure maldevelopment, which
includes the palatine tonsils, tonsillar fossa, and the hyoid bone.
US and CT are both helpful for delineation of the cyst and
fistulous tracts. When infected, proteinacous debri, hemorrhage,
wall thickening of the cyst, and loss of the normal soft tissue
planes can be demonstrated by CT or US (figures 4 and 5). Only
complete excision of both the cyst and sinus tract secures
effective treatment and prevents recurrence.
Carcinoma can rarely occur from unresected branchial cleft cysts.
Ranulas are uncommon congenital lesions that present as floor of
the mouth masses. They occur secondary to obstruction or an
imperforate sublingual salivary, and, less commonly, a
submandibular duct, presumably due to traumatic, congenital, or
Usually, ranulas are found in the sublingual space. If they are
large, they can present as an anterior cervical triangle mass. If
the ranula is not infected or ruptured, they are seen as large
simple cystic structures on US.
If they rupture, they tend to extravasate caudally, hence its name
of "plunging ranula." Similar findings can be assessed by CT
Ranulas are self-limiting lesions, as they sometimes
spontaneously regress or rupture.
Marsupialization via incision and free drainage into the oral
cavity is the preferred treatment.
The congenital form of cervical lymphatic malformations result
from incomplete or lack of drainage of the lymphatic system to the
superior vena cava (SVC). In general, these lesions may be
categorized according to their size as lymphangioma simplex,
cavernous lymphangioma, and cystic hygroma with the latter being
the largest one.
Of these three, cystic hygroma is the most common and will be
Cystic hygromas usually occur in the posterior cervical triangle
and present clinically as a soft, painless mass that can grow
slowly with age.
Radiographically, cystic hygromas have a variable presentation.
Uncomplicated cystic hygromas will present as a large simple cystic
mass by US and CT with or without septations (figure 7). They can
sometimes undergo spontaneous or traumatic hemorrhage or become
infected, manifesting as a complex, heterogeneously echogenic
cystic mass with possible septations. The wall may be thickened
with or without adjacent fat stranding by CT or demonstrate poorly
defined boundaries of surrounding tissue by US.
Because cystic hygromas may be associated with genetic
conditions such as Turner's, Klinefelter's, and Down's syndromes,
as well as partial trisomies, screening for concomitant
extracervical lesions should be performed.
Prior to surgery, the extent and relationship with the
neighboring structures and vascularity of the mass should be
assessed. To minimize the chance for recurrence, the mass should be
excised completely. Nonsurgical approaches such as intralesional
bleomycin injection have results similar to surgical excision.
The lesions generally recur after simple needle aspiration.
Dermoid and epidermoid cysts are rare. When they occur, they are
due to entrapment of ectodermal elements underneath the skin.
Epidermoids contain stratified squamous epithelium. Dermoids
contain stratified squamous epithelium in addition to skin
appendages, which can include sebaceous glands, sweat glands, and
hair follicles. When they occur in the neck, they are usually found
at the floor of the mouth, similar to ranulas, and less commonly
appear as an anterior midline mass that lies over the hyoid bone
and can be mistaken for a thyroglossal duct cyst.
Preoperative radiographic evaluation should center on
delineation of the cystic margins and assessment of possible occult
deep and superficial draining sinuses.
By US, dermoid and epidermoid cysts are known to have internal
echoes with or without posterior acoustic enhancement.
The internal echogenicity is expected because they can potentially
have secretory, glandular tissue, and keratinous debris. By CT,
dermoid and epidermoids are known to variably enhance as well as
demonstrate fat and dystrophic calcifications.
Therapy for dermoid and epidermoid cysts is complete excision of
the cyst and potential sinus tracts.
Mixed neck masses
Congenital vascular anomalies are a result of abnormal
endothelial proliferation and are classified into two
subcategories: hemangiomas and vascular malformations.
Hemangiomas consist of hyperplastic endothelial cells that grow
rapidly in size during the first year of life, but usually regress
spontaneously, except in 10% to 20% of cases.
Kassabach-Merritt syndrome is thrombocytopenic coagulopathy in
association with large hemangiomas. This syndrome carries a poor
prognosis with a 30% to 40% mortality rate.
Vascular malformations, unlike hemangiomas, are composed of
morphologically normal vascular tissue, which can include arterial,
capillary, venous, lymphatic, or a combination of the four tissue
types. They do not regress spontaneously but tend to grow
proportionately with the child.
By contrast-enhanced CT, both vascular anomalies demonstrate an
intense clustering of enhancing vessels (figure 8). By ultrasound,
both are usually homogenous and hyperechoic. Hemangiomas
demonstrate a high diastolic flow and low resistive index. Vascular
malformation Doppler findings are variable and are dependent of the
predominant vascular tissue type present.
Management for most hemangiomas is conservative since they
usually regress spontaneously. Corticosteroids, interferon, laser,
embolization, and surgical excision are potential therapies, if
vital structures such as the airway is compromised.
Therapy for symptomatic vascular malformations is necessary,
however, given that they do not regress spontaneously. Therapy can
include embolization, surgical resection, and laser ablation.
The neck is the second most common location for teratomas after
Neck teratomas have malignant characteristics less frequently than
those found in the sacrum. Because of their tendency to increase in
size rapidly and their potential adverse location, such as near the
airway, work-up and therapy is for prompt complete excision.
On CT, these lesions can have a variable presentation. They can
present as large, enhancing, heterogeneous masses with both
soft-tissue and cystic components (figure 9). Given the high
morbidity and mortality associated with recurrence secondary to
incomplete resection, preoperative delineation of tumor extent and
relationship with neighboring structures is important.
Fibromatosis colli represents fibrosis and shortening of the
sternocleidomastoid muscle that causes torticollis. It is felt to
occur secondary to abnormal fetal positioning. Predictably, it is
seen in higher frequency in patients who have congenital dysplasia
of the hip.
Clinically, fibromatosis colli presents in the newborn period
with tilting of the head to the affected side of the neck with an
associated ipsilateral sternocleidomastoid soft-tissue mass.
By ultrasound, it shows a near homogeneous, predominently
hyperechoic mass surrounded on all sides by a thin rim of
hypoechoic, normal sternocleidomastoid muscle
(figure 10). Fine-needle aspiration of the mass is usually
performed for diagnosis.
Physical therapy is the first line of treatment.
Surgical transection of the affected sternocleidomastoid muscle is
indicated if there is persistent facial hemihypoplasia.
In summary, location and radiographic morphology of congenital
neck masses help narrow the differential diagnosis. Given the
superficial nature of neck masses and patient age, initial work-up
with ultrasound is ideal. Axial imaging is helpful for delineating
presurgical anatomy or when ultrasound findings are equivocal.