Common Pediatric Head and Neck Masses

Join us for our 28th episode, where we discuss common pediatric head and neck masses with a focus on the two most common presentations, including thyroglossal duct cysts and branchial cleft cysts! Tune in for another episode later this year for an episode on an approach to pediatric head and neck masses. Thank you to Dr. Mark Khoury for the reviewing of the content in this episode.

Show Notes

Introduction 

Welcome to The Oto Approach, a podcast created by medical students for medical students, where we cover all things in otolaryngology – head and neck surgery. I'm today’s host, Hassan, a third-year student at Ottawa U, and today we will talk a bit about branchial cleft cysts and thyroglossal duct cysts. Thank you to Dr. Mark Khoury for reviewing the content of this script.

Branchial Cleft Cysts

First, we should figure out what a branchial cyst and later we can discuss thyroglossal duct cysts. They’re both a part of the differential for pediatric neck masses, and fortunately, they both generally have one of the best prognoses. Branchial cysts are a lateral swelling in the upper part of the neck, generally anterior to the sternocleidomastoid but deep to the platysma. It can have a fistula (sometimes), and accounts for 20% of all neck masses in children (Although thyroglossal duct cysts are the most common neck mass by far, which we will get to!). Branchial cysts, however, are usually described as types one through four. Although, you’ll find that Types 3 and 4 are difficult to distinguish clinically and on imaging. So, let’s say they’re types 1, 2, and 3 + 4 (depending on where they are). Unfortunately, this means we must discuss everyone’s worst nightmare, embryology.

Embryology/Anatomy

Embryologically, we can jump straight to the fourth week of gestation and up to the seventh week. Branchia is the Latin word for gills, and the embryological branchial arches resemble gills, which is why it was given this name etymologically. Know you know! There are four arches, each with an accompanying pouch (internal) and cleft (external) to the arch (look at your knuckles, the knuckle is the arch, and the grooves are the clefts). The branchia are derived from the mesoderm, and covered in a layer of ectoderm, forming these arches at 4 weeks gestation. Each arch (made of a pouch and cleft) develops into a group of nerves, vessels, and muscles. As the embryo develops, these branchia will “obliterate,” a fancy term for narrow until they disappear. If they don’t fully close, then you can have either a space with fluid form (Cyst), a sinus, or a fistula (opens to the environment). Normally, these spaces will close off by the 7th week. The type of branchial cysts relates to corresponds the arch that was affected. They can present in such different locations because the cyst develops from the course that the branchial cleft migrates until it closes off. If you’re lucky you might be able to palpate the cord following the tract. Inside the cyst, you’ll find squamous epithelium lining with keratinous debris and lymphoid tissue inside. The most common branchial cleft cyst being the second type/arch, which we can talk about in a second. Fortunately, even if the embryology is intimidating, you can predictably find each type of branchial cleft cyst according to its embryological origin.

Presentation

Usually, this anomaly presents as a lateral neck mass in patients under five years old following an URTI (enlarges), and sometimes can have fistulas, which can really alert you to their presence. If a fistula tract forms, the connection is generally between the pharynx or larynx and the external skin. Generally, kids present with a painless mass either in the preauricular space (Type 1), or the angle of the mandible, or /anterior and medial to the SCM/submandibular (Type 2) (95% of branchial cleft cysts), lower anterior neck [more likely to present as abscess, fistula tracts, or with stridor] (Type 3), and the rarest, type 4, which presents similar to the third type, and is usually indistinguishable from Type 3. Knowing that the second type is overwhelmingly the most common, it’s also important to know anatomically where it’s tract can course. Generally, the course of a second brachial cleft cyst travels deep to the platysma and passes between the internal and external branches of the carotid artery, and courses superficially to the glossopharyngeal and hypoglossal nerves, and ultimately connects to the tonsillar fossa. You can have a cyst or sinus form anywhere along this course. Interestingly, the second type is also associated with some genetic syndromes, so if you have features of say branchio-oto-renal syndrome, such as bilateral skin pitting around the neck, you should increase your suspicion of this cyst.

Prevalence

The true incidence and prevalence of branchial cysts are unknown despite being relatively common. Partly, this is since they can present so differently and often do not cause any issues. In some cases, they may not present until late adulthood. 10% of cases present with bilateral anomalies. Although, if you find a presentation in adulthood, it is very important to rule out a head and neck malignancy, as they can present like branchial cleft cysts, but may represent cystic nodal metastases. Estimates suggest that it exists in 2-3% of the pediatric population.

Etiology

Branchial cleft cysts have an unknown etiology and are most commonly congenital malformations. However, treatment is still important despite the benign presentation to prevent future imaging and if it becomes infected, repeated courses of antibiotics.

History: Signs and Symptoms

Typically, on history, a patient will complain of a painless lateral neck mass, that has been present but becomes more prominent as the child becomes older. Sometimes, they become enlarged, tender, or even form an abscess following a URTI, as mentioned previously. Reasons to be concerned on history and exam are if the patient describes any purulent drainage, stridor, dysphagia, or shortness of breath. Generally, these symptoms point to the possibility of airway compression from the cyst to varying degrees. After a URTI, a change in size can happen in ¼ of patients. Alternatively, a patient who has repeatedly undergone a neck I&D without resolution of symptoms should be investigated for a branchial cleft cyst. Patients and their parents should always be asked screening symptoms for lymphomas, regardless of the history.

Physical exam and diagnosis

A Good head and neck examination includes inspection of the head and neck, palpation, assessment of lymphadenopathy, and expression to see if there is any fluctuance or drainage. Any warmth, redness, fluctuance, and purulence should concern you for an abscess.

Imaging can confirm the presence of a branchial cyst, but the physical exam is the most important in diagnosis. Ultrasound can characterize the complexity and presence of a cyst, and MRI can provide better resolution if it is unclear. A CT technically also be done, although due to radiation concerns in young children it is generally not used. If there is a concern for a sinus tract, a sinogram can be done by using dye to determine the volume of the cyst. If you feel there may be a fistula, laryngoscopy may prove useful to visualize internally. If there is any concern for a malignancy, consider a CBC and FNA to help you. Remember that 80-90% of all pediatric neck masses are benign!

Differential

What else could this neck mass be? There is a long list of diagnoses for lateral pediatric neck masses, however, the easiest way to remember them is by breaking them down by etiology.

For example, vascular causes include hemangiomas, AVM, lymphatic malformations, while inflammatory causes include lymphadenitis, sarcoidosis, Kikuchi-Fujimoto. Congenital causes include branchial anomalies and laryngoceles. Malignant causes include thyroid malignancy, neuroblastoma, and lymphoma. Lastly, consider traumatic causes in infants, including pseudotumor if infancy.

Treatment

Treatment of a branchial cleft cyst involves elective excision, as branchial clefts may become infected, enlarge over time, or very rarely, may have a risk of malignancy. Urgent excision is only required if there is airway compromise or if the abscess is large. If the cyst is infected, you can usually treat with systemic antibiotics and aspiration, and surgery only once the infection is fully resolved. I&D is generally not required unless there is a significant abscess.

During the surgery, methylene blue can be injected to alert the surgeon to the presence of a fistula or sinus. If for whatever reason the patient cannot undergo surgery, ethanol ablation has been used as an alternative treatment but is not first line. Surgery involves injection of lidocaine, and ellipse incision around the tract opening, followed by horizontal stepladder incisions to fully dissect the tortuous path of the cyst. The subplatysmal flaps are raised, and blunt dissection is used to dissect the tract. Superior laryngeal, hypoglossal, and glossopharyngeal nerves are identified to avoid injury, followed by wound irrigation and hemostasis once the tract is excised. Penrose drains are placed, and the layers are closed.

Clinical pearl

Air around the thyroid in a child on ultrasound or CT is highly suggestive of a third/fourth branchial cleft cyst

Thyroglossal Duct Cyst

TGD are the most common congenital neck mass in the pediatric population. These are cysts, presenting as lumps that develops near the thyroid gland, and are diagnosed at birth or early childhood. The name of the thyroglossal duct cyst comes from the duct that connects the tongue and thyroid gland during fetal development, and if it does not close you can have fluid accumulate in this tract. Much like branchial cleft cysts, unless there is airway compression or infection, the cysts are benign!

Embryology/Anatomy

TDCs are the most common congenital neck mass in the pediatric population. At 3 weeks of gestation, the thyroid gland forms from a diverticulum at the oral tongue (the foramen cecum). As development continues this diverticulum descends to fuse with components of the fourth and fifth branchial pouch, anterior to or through the hyoid, and to the thyroid’s final location in the neck. At 5 to 8 weeks, the tract formed by this descent obliterates leaving the foramen cecum proximally and the pyramidal lobe of the thyroid distally. Incomplete obliteration results in a TDC anywhere along this tract. You can kind of think of it as a tube connecting the base of the tongue to the thyroid, and the tube must elongate downwards and anteriorly to bring the thyroid into its regular position, and then instead of disappearing, it stays. Because of this connection, a TDC generally elevates with extrusion of the tongue, because it is quite literally being stretched! In about half of all people with this anomaly, the end of the thyroglossal duct forms the pyramidal lobe of the thyroid.  In normal anatomy, the TD should disappear by 10 weeks. The TDC is usually lined with respiratory and squamous epithelium, and the distal end connected to the thyroid may have thyroid follicles. Interestingly, if there is complete failure of the thyroid to descend, you end up with a lingual thyroid!

Presentation

Unlike branchial cysts, which are lateral masses, TDC’s present at mobile, cystic, and midline mass inferior to the hyoid (25-65% of presentations). They are mostly asymptomatic, but like branchial cysts, can present with abscess or sinus formation. It is extremely rare for them to have malignant transformation (Approximately 1% of all cases) but is something to consider. Fortunately, the surgical procedure if it is malignant is the same. It is also worthwhile to consider that TCDs can recur even after excision, so if someone has had surgery you should keep it on your differential.

Prevalence

TDC’s are the most common pediatric neck mass by far and are present in 7% in the population! That’s a lot of TDC’s! They occur equally in males and females.

Etiology

TDCs have an unknown etiology and are cryptic in their cause, meaning that they are congenital anomaly without anyone really knowing why they happen, only how they happen.

 However, treatment is still important despite the benign presentation to prevent the rare chance of malignant transformation, recurrent infections, repeat antibiotics, and excess radiation through unnecessary imaging.

History: Signs and Symptoms

On history, it’s very common for parent to come in mentioning their child has a painless midline mass from birth that has become more pronounced, usually after an infection. Sometimes, like branchial cysts, they may present as abscess of the neck. If this is the case, make sure to rule out a deep space neck infection. However, most children usually feel unbothered by it and may feel that cosmetically it is bothersome (Moreso to the parent, usually!).

Physical exam and diagnosis

Just like branchial cysts, a good head and neck examination is key. Inspect the mass, palpate it, assess for lymphadenopathy, or if there is any fluctuance or drainage. Any warmth, redness should point you to the possibility of an abscess.

The key diagnostic imaging that can be used is ultrasound. It is painless, has no radiation, and can be done at the bedside. On imaging, it will show a cystic mass with clear borders. CT and MRI can also be used to assess the thyroid tissue but is usually not needed. Thyroid testing/labs are generally not needed unless you suspect significant ectopic thyroid tissue and clinical manifestations of thyroid disease. Biopsy can be helpful if the diagnosis is not clear or if there are any concerning features of malignancy.

Differential

Midline neck masses, what could it be? Always keep in mind your lateral neck mass differentials, as they are not always perfectly lateral. However, for pediatric midline masses, a similar etiological approach is useful.

Things to consider include vascular causes, such as hemangiomas, AVM, lymphatic malformation, pseudotumor of infancy. Consider infections like a plunging ranula or lymphadenitis. You should also consider of course... TCD’s, and things like lingual or ectopic thyroids, dermoid cysts, teratomas, thymic cysts. Lastly, always make sure there is no malignancy, particularly thyroid or salivary malignancies for this midline presentation

Treatment

Emergency treatment is almost always unnecessary unless there is airway compromise or recurrent infections! That means you have time to take your time and treat it surgically electively rather than urgently. To treat TCD’s, there is a surgical procedure called the Sistrunk procedure. It can only be done if there is no acute infection. If there is, treat with antibiotics and the surgery should always be done after resolution. This surgery is quite safe and has an excellent prognosis. Rarely, recurrence can occur if there is incomplete excision or intraoperative rupture. There can also be laryngotracheal injury, although this is incredibly rare. The Sistrunk procedure involves incision into the platysma, the cyst will be below the sternohyoid muscles, and then it gets dissected from surrounding tissues. The mid-portion of the hyoid is also removed, as well as a core of tissue from the base of the tongue. The wound is then closed, and a drain is placed if the cyst was sufficiently large enough to warrant it. Patients are discharged and usually only one post-operative follow-up is required. You may be wondering why the hyoid is removed, and that’s a great question. Recurrence rates before taking a part of the hyoid out used to be as high as 50%, but with excision of the hyoid, the rates of recurrence became closer to 10%. The procedure pioneer, Walter Sistrunk, did this so that the tract of the cyst could be adequately resected to ensure there was no connection between the cyst and foramen cecum. Now you know!

Ending

Thank you so much for listening to our podcast today on pediatric neck masses! If you stuck around, thanks for listening all the way through and we hope you’ll tune in to our next episode. Please head to our website at www.theotoapproach.com for our show notes, and to sign up for our newsletter to stay up to date with our latest episodes.

References

1.      Pasha R, Golub JS, editors. Otolaryngology-head and neck surgery: clinical reference guide. Plural publishing; 2021 Sep 8.

2.      Scholes MA, Ramakrishnan VR. ENT Secrets E-Book. Elsevier Health Sciences; 2022 May 9.

3.      Bluestone CD, Simons JP, Healy GB, editors. Pediatric otolaryngology. PMPH-USA; 2014.

4.      Coste AH, Lofgren DH, Shermetaro C. Branchial Cleft Cyst. InStatPearls [Internet] 2023 Jun 30. StatPearls Publishing.

5.      Amos J, Shermetaro C. Thyroglossal duct cyst. InStatPearls [Internet] 2023 Jun 26. StatPearls Publishing.