Congenital Malformations of the Head and Neck

Key Points

1.
A Sistrunk procedure involves removal of a thyroglossal duct cyst along with the central portion of the hyoid bone, resulting in decreased recurrence rates of the congenital cyst.
2.
Tracheoesophageal anomalies are usually evident at birth because of significant feeding issues and require urgent intervention.
3.
Newborns are obligate nasal breathers for at least the first month of life, and the presence of bilateral choanal atresia is a life-threatening airway.
4.
Hemangiomas are typically absent at birth, proliferate over the first year of life, and eventually involute.
5.
Lymphatic malformations are not true tumors but grow proportionally with the patient and can rapidly expand with bleeding, infection, or trauma.

Pearls

1.
Branchial cleft anomalies track deep to the structures of their own arch and superficial to the structures of the subsequent arch.
2.
Always evaluate for a normal thyroid gland prior to removing a thyroglossal duct cyst.
3.
The pseudotumor of infancy (SCM tumor) responds to conservative treatment by 1 year of age in 80% of cases.
4.
A stridulous child with a concomitant hemangioma, particularly in the “beard distribution” of the face, should raise suspicion for a subglottic hemangioma.

Questions

1 What is the differential diagnosis for a congenital or pediatric neck mass?

The differential diagnosis for a pediatric mass of the head and neck can be organized based on anatomic distribution or possible etiology. The mnemonic “KITTENS” (K: congenital anomalies; I: infectious/inflammatory; T: trauma; T: toxic; E: endocrine; N: neoplasms; S: systemic disease) is useful for guiding a comprehensive list. The lesion varies according to anatomic distribution, age at presentation, and growth history.

Congenital lesions represent the most common neck mass in children and are most often cystic. Midline lesions may be dermoid cysts or thyroglossal duct cysts, while branchial cleft anomalies are observed in the lateral neck. Acquired masses, such as lymphadenitis or atypical mycobacterial infections, are most often infectious or inflammatory. Neoplasms are relatively rare in the pediatric population but must always be considered in the differential; Hodgkin and non-Hodgkin lymphomas, neuroblastoma or rhabdomyosarcoma may initially present as a neck. See Table 52.1 for a detailed list.

Table 52.1

Differential Diagnosis of Congenital Neck Mass

Adapted from Wetmore R, Potsic W: Differential diagnosis of neck masses. In: Cummings CW, Frederickson JM, Harker LA, et al, eds: Otolaryngology Head and Neck Surgery , 3rd ed, St. Louis, 1998, Mosby, pp 248–261.

LOCATION	DIAGNOSIS	FEATURES
MIDLINE
	Thyroglossal duct cyst	Overlies hyoid or thyroid notch, elevates with swallowing or tongue protrusion
	Dermoid cyst	Moves with skin, typically submental
	Teratoma	Firm, CT showing calcification, rare in neck
	Plunging ranula	Midline or slightly lateral, cystic, extends to floor of mouth
LATERAL
	Branchial cleft cyst	Along anterior border of SCM, fluctuant, periodic infections
	Lymphatic malformation	Soft, compressible, often extends posterior to SCM, transilluminate
	Pseudotumor of SCM	Firm, painless, discrete, fusiform mass in newborn
EXTENSIVE
	Lymphatic malformation	Thin-walled, macrocystic vs. microcystic, variable anatomic involvement
	Vascular malformations	Red/bluish mass, pulsatile (AVM), strawberry (hemangioma), size may increase with crying

All pediatric neck masses require a detailed history and physical examination. Laboratory analysis may be helpful in establishing a diagnosis or ruling out more aggressive lymphoproliferative processes. Ultrasound imaging is useful in differentiating solid or cystic lesions, while cross-sectional imaging by CT or MRI provides more details regarding anatomic considerations. While some masses may be diagnosed through noninvasive measures, many will require surgical biopsy for a definitive diagnosis.

2 How does a thyroglossal duct cyst develop?

During development, the thyroid diverticulum forms at the midline base of the tongue (foramen cecum). The developing thyroid descends through the neck, anterior to or through the hyoid bone, and comes to rest in its final position in the lower neck, inferior to the cricoid cartilage. The tract that the thyroid follows from the base of the tongue to the anterior neck (thyroglossal duct) normally obliterates; however, if this process is incomplete, a thyroglossal duct cyst may persist anywhere from the foramen cecum to the pyramidal lobe of the thyroid gland. The most common location is anterior or superior to the hyoid in the midline or slightly paramedian. Thyroglossal duct cysts are the most common congenital neck masses found in pediatric patients and may account for up to one-third of pediatric neck masses.

3 What needs to be seen on imaging before removing a thyroglossal duct cyst?

It is important to identify the presence of a normal thyroid gland prior to the excision of a thyroglossal duct cyst. In rare instances the thyroid gland can arrest its descent during development, and what is perceived as a thyroglossal duct cyst may actually be the patient’s only functional thyroid tissue. Surgery to excise this lesion could then leave the patient hypothyroid and require lifelong supplementation.

4 What are the complications of an untreated thyroglossal duct cyst?

An untreated thyroglossal duct cyst may become infected and require antibiotics, aspiration, or incision and drainage. Large cysts can result in dysphagia, dysphonia, and airway obstruction in severe cases. While uncommon (<1% of cases), thyroglossal duct cysts can harbor malignant thyroid cells, most commonly a well-differentiated thyroid cancer such as papillary thyroid carcinoma.

5 How is a thyroglossal duct cyst managed surgically?

The standard of care for thyroglossal duct cyst removal is a Sistrunk procedure in which the entire thyroglossal duct cyst, duct, central hyoid bone, and a cuff of the suprahyoid musculature from the base of the tongue are removed. Recurrence rates following this procedure are less than 5%.

6 What is the differential diagnosis for a midline congenital neck mass?

Thyroglossal duct cyst, dermoid, teratoma, plunging ranula, lymph node, thymic cyst, foregut duplication cyst, and laryngocele.

7 What is the difference between a teratoma and a dermoid?

Teratomas and dermoids may be differentiated histologically: a teratoma is made from all three germ cell layers (endoderm, ectoderm, and mesoderm) and dermoid cysts are only made from two germ cell layers (ectoderm and mesoderm). Teratomas are often larger and more symptomatic than dermoids and are frequently found on prenatal ultrasound. Dermoids are much more common than teratomas. Surgical excision is the preferred treatment for both, and incomplete excision may result in recurrence.

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