Neck Cysts

Most neck masses in children are benign inflammatory lesions, which can be successfully treated medically with antibiotics. Most neck masses in children that require surgery for diagnostic and therapeutic purposes are congenital in origin. Thyroglossal duct cysts (TGDCs) and branchial cleft cysts are the 2 most common congenital lesions.

Baer first described the branchial apparatus in 1827. The branchial arches begin to develop during the second week of gestation. During the fourth week of fetal development, 5 ridges, known as branchial arches, form on the ventrolateral surface of the embryonic head. Each arch contains mesoderm from which cartilage, muscle, and bone develop. Each arch is separated from the other arches by an external cleft of ectodermal origin. Each arch also has an internal pouch of endodermal origin and an associated cranial nerve, artery, and cartilage.

The anatomic location of a branchial cleft abnormality represents the presumed branchial cleft of origin. Branchial cleft anomalies can manifest in several different forms, including the following:

• Fistula - Epithelial-lined tract with both an internal and an external opening

• Sinus - Incomplete fistula with either an internal or an external opening

• Cyst - Epithelial-lined cavity with neither an internal nor an external opening

Frequency

More than 90% of branchial cleft anomalies arise from the second branchial cleft system. Approximately 8% of branchial cleft anomalies arise from the first branchial cleft system. Cysts arising from the third and fourth branchial cleft system rarely occur.

Branchial cleft anomalies and thyroglossal duct cysts (TGDCs) occur with equal frequency in males and females. Branchial cysts are twice as common as either branchial sinuses or fistulas. TGDCs are the most common mass found in the midline of the neck in children.

Branchial cleft anomalies

Several theories are proposed to explain the genesis of branchial cleft anomalies. Incomplete closure of branchial clefts and pouches with failure of obliteration of the cervical sinus of His is suggested as a possible mechanism. Incomplete closure of branchial clefts and pouches with rupture of the branchial plate is another possible mechanism.

Thyroid gland anomalies

The thyroid gland forms as a diverticulum from the floor of the pharynx (tuberculum impar) at a site that later becomes the foramen cecum of the base of the tongue. The thyroid gland then forms 2 lobes and descends along a hollow canal called the thyroglossal duct in the midline of the neck. During the descent, the thyroglossal duct passes in close proximity to the developing hyoid bone. The thyroglossal duct normally involutes; however, when involution does not occur, the potential for development of a thyroglossal duct cyst (TGDC) increases. Arrest in the normal descent of the gland results in ectopic thyroid tissue.

The recognition of a cyst in the neck may not occur until decades later, commonly in association with a minor upper respiratory infection. This suggests that the potential for a cyst had existed for years. Many patients with a TGDC have some thyroid tissue in the cyst; therefore, thyroglossal duct anomalies might be a better term for their condition.

A study by Park et al indicated that adult patients, particularly men, who undergo radioactive iodine therapy may be more prone to TGDCs. However, the treatment did not seem to significantly affect the location, size, and shape of the cysts.[5]

Lymphatic malformations

Lymphatic malformations, which include lymphangioma and cystic hygroma, are areas of localized abnormal development of the lymphatic system. These malformations most commonly occur in the head and neck area. Although the exact embryonic origin of lymphatic malformations is unknown, several etiologies have been proposed. Possible causes include failure of the venous and lymphatic systems to connect, abnormal sequestration of the lymphatic tissue during embryogenesis, and abnormal budding of lymphatic structures from the cardinal vein. Other likely etiologies that focus on an acquired process include infection, trauma, and lymphatic obstruction.

Branchial system anomalies can manifest as a sinus, fistula, or cyst. Branchial cleft sinuses with external openings are usually associated with the first and second branchial cleft arches. Branchial cleft sinuses with internal openings are usually associated with the third and fourth arches.

First branchial cleft anomalies are subdivided into 2 types based on anatomic location. In type 1 first branchial cleft anomaly, the cyst or sinus opening can be located medial, inferior, or posterior to the conchal cartilage and pinna. A sinus tract, when present, parallels the external auditory meatus. In a type 2 first branchial cleft anomaly, the cyst and sinus tract are located in the anterior neck, always superior to the hyoid bone. A sinus tract or fistula, when present, travels over the angle of the mandible and through the parotid gland to terminate around the bony-cartilaginous junction in the external auditory meatus. The relationship to the facial nerve and parotid gland is variable with first branchial cleft cysts.

Second cleft anomalies are the most common of the branchial system. When an external opening is present in a second branchial cleft anomaly, the opening is located along the anterior border of the sternocleidomastoid muscle near the junction of the lower- and middle-third portions of the muscle, below the level of the hyoid bone. An internal opening, when present, is located in the tonsillar fossa. When present, a fistula ascends from the lower neck along the carotid sheath and crosses over the hypoglossal nerve and glossopharyngeal nerve. The fistula then passes between the internal and external carotid arteries to end in the tonsillar fossa. Second branchial cleft cysts are more common than sinuses or fistulas. The location of the cyst can be anywhere along the course of the fistula but most commonly is in the anterior triangle of the neck below the level of the hyoid bone.

Third branchial cleft anomalies are rare. When present, the external opening is located in the same location as a second branchial cleft anomaly; that is, along the anterior border of the sternocleidomastoid muscle at the junction of the middle and lower third portions of the muscle. The internal opening is located in the pyriform sinus rather than in the tonsillar fossa. The fistula tract ascends along the carotid sheath posterior to the internal carotid artery, then between the hypoglossal and glossopharyngeal nerves. The fistula tract then pierces through the thyrohyoid membrane and opens into the pyriform sinus. Cysts can occur at any location along this course but are usually found in the anteroinferior cervical triangle on the left side.

In 1972, Sanborn reported the first case of a fourth branchial arch anomaly.[6] If a fourth branchial arch anomaly occurs, it may have (1) an internal opening located near the apex of the pyriform sinus, (2) a fistula or sinus tract that travels between the superior and inferior laryngeal nerves, or (3) an external opening along the anterior border of the sternocleidomastoid muscle in the lower neck. The literature contains more than 30 cases of reputed fourth branchial cleft anomalies. Most are on the left side, with only 5 occurring on the right side.

Branchial cleft anomalies

Branchial cleft cysts manifest in a different manner than branchial sinuses and branchial fistulae. The typical branchial cleft cyst, in the absence of infection, manifests as a nontender, smooth, round mass located along the anterior border of, or just deep to, the sternocleidomastoid muscle. Depending on the arch of derivation, the location can be anywhere from the external auditory canal to the clavicle. Branchial cleft cysts usually enlarge gradually and often are not detectable until the second or third decade of life.

Branchial cleft cysts that manifest in early childhood usually occur with an acute and painful enlargement of the cysts secondary to an upper respiratory infection. Branchial cleft cysts commonly increase in size in the presence of an upper respiratory tract infection and then decrease in size as the infection resolves.

An infected branchial cleft cyst can progress into an abscess or rupture spontaneously to form a draining sinus tract. Neonatal patients and patients with larger cysts can present with aerodigestive tract compromise and associated symptoms of stridor, dyspnea, and dysphagia. Second and third branchial cleft cysts can cause stridor with life-threatening airway obstruction in neonates.

In contrast to those patients with branchial cleft cysts, patients with branchial cleft sinuses and fistulas often present soon after birth because the external opening is visible on the skin. Branchial cleft fistulas and sinuses may also be palpable as a fibrous cord extending along the anterior border of the sternocleidomastoid muscle. Mucus drainage may occur from the external opening. Secondary infections from cutaneous organisms, most commonly Staphylococcus aureus and group A beta-hemolytic streptococci, cause purulent drainage and erythema and edema.

An infected first branchial cleft sinus or fistula may cause aural drainage in the absence of otitis media or otitis externa. A child presenting with both a draining ear and a tender mass in the neck may rarely have a first branchial cleft cyst associated with a sinus or fistula tract. A child presenting with a mass in the neck and a draining tract along the anterior border of the sternocleidomastoid muscle may have a second or third branchial cleft anomaly. A child with paratracheal swelling associated with tenderness and fever may have acute suppurative thyroiditis. Multiple authors have documented the spread of bacteria from an internal opening in the pyriform sinus in third branchial cleft anomalies.

Thyroglossal duct cysts

A thyroglossal duct cyst (TGDC) is the most common mass found in the midline of the neck. The mass is usually located at or below the level of the hyoid bone, although a TGDC can be located anywhere from the foramen cecum to the level of the thyroid gland.

Most patients with a TGDC present with asymptomatic masses in the midline of the neck. The literature reports that most of these lesions occur in patients younger than 30 years, although according to a study by Thompson et al of 685 TGDCs, the incidence of these lesions peaks in the first and fifth decades of life.[7]  Interestingly, over the last decade, a number of older patients are presenting with a TGDC, some of whom are aged 80-90 years. Recurrent inflammation associated with infection of a TGDC is not uncommon. When infection is present, the cyst often enlarges and an abscess may form. Spontaneous rupture with secondary sinus tract formation can also occur.

The study by Thompson et al found a skin fistula associated with about 10% of TGDCs, with the fistula occurring twice as often in pediatric patients as in adults.[7]

Lymphatic malformations

Approximately half of all lymphatic malformations are diagnosed at birth, and 90% are diagnosed by age 2 years. With today's use of prenatal ultrasonography, diagnosing lymphatic malformations before birth is not uncommon. Most of these neck cysts present as slow-growing cystic cervical masses. When the mass is located in the suprahyoid location, the patient can present with respiratory compromise. Infection and hemorrhage of the malformation can cause sudden enlargement with respiratory compromise.

Treat branchial cleft anomalies, thyroglossal duct cysts (TGDCs), and lymphatic malformations for several reasons, including the following:

• Removing the lesion provides a pathological diagnosis.

• When infected, branchial cleft anomalies and TGDCs can cause acute pain and aerodigestive tract compromise.

• Branchial cleft anomalies and TGDCs can cause cosmetic deformity.

• Malignancy may occur (rare).

First branchial cleft fistulas and sinuses have a variable relationship to the facial nerve. No reliable methods are currently available to determine definitively the relationship between the sinus tract or fistula and the facial nerve prior to surgery. Surgeons, therefore, must be prepared for dissection of the facial nerve prior to embarking upon surgery for a first branchial cleft anomaly. A facial nerve monitor may be helpful.

Acute infection is a relative contraindication for surgical excision. Acute infection makes dissection more difficult and increases the risk of injury to surrounding structures. If possible, treat acute infection with appropriate IV antibiotics. If the infection is unresponsive secondary to abscess formation, incision and drainage or repeated aspiration in conjunction with antibiotic treatment may be required.

To avoid complications, consider several studies in the preoperative evaluation of a thyroglossal duct cyst (TGDC). Confirmation of a normally functioning thyroid gland is important; therefore, always palpate the thyroid gland during the physical examination. If the gland is not palpated, ultrasonography or CT scanning may be valuable. If an ectopic thyroid gland is mistakenly diagnosed as a TGDC and removed, the patient requires lifelong thyroid replacement to prevent myxedema and complications of hypothyroidism.

Although not always the case, the patient with an ectopic thyroid often is hypothyroid and consequently has elevated thyroid-stimulating hormone (TSH). If hypothyroidism is suggested by the history, then a TSH test may be useful; however, an ectopic thyroid gland cannot be ruled out even in the presence of reference range TSH levels and a clinically euthyroid history. For this reason, ultrasonography, CT scanning, thyroid scanning, or MRI may be warranted to document a normal thyroid gland.

Preoperative imaging studies, including high-resolution CT scanning, contrast fistulography, and barium swallow esophagraphy, may be helpful in selective cases. These studies may be useful in defining the exact location, size, and course of the branchial cleft anomaly.

CT scanning is helpful in most situations. In the presence of an external sinus or fistula in the neck, fistulography may provide additional information on the course of the tract. In a patient with a history of recurrent lateral neck abscess, in which a branchial cleft anomaly with a possible internal sinus opening is suspected, a barium swallow esophagraphy may provide helpful information.

A study by Oyewumi et al indicated that ultrasonography can be used to differentiate thyroglossal duct cysts from midline dermoid cysts in children. According to the investigators, the study, which involved 91 patients, found three ultrasonographic variables — internal septae, an irregular wall, and solid components — that independently predict the presence of a thyroglossal duct cyst over a dermoid cyst.[8]

A thorough history and physical examination is usually all that is necessary to diagnose anomalies of the branchial cleft and thyroglossal duct. The history of a patient with a branchial cleft anomaly usually reveals a neck mass that may have fluctuated in size and level of pain and discomfort.

In adults with a cystic mass in the neck, obtain a careful history of squamous cell cancer risk factors. A complete physical examination of the head and neck must be performed on all patients. Perform a direct laryngoscopy in all patients who might have a metastatic cervical neck cyst secondary to an unknown primary squamous cell carcinoma. Direct laryngoscopy with hypopharyngoscopy and barium swallow esophagraphy often are useful in the treatment of a patient with a history of recurrent lateral neck abscess in whom a branchial cleft anomaly with a possible internal sinus opening is suspected. If an internal opening is observed on laryngoscopy, intubate the tract with a probe or a balloon embolectomy catheter. This facilitates identification and dissection of the sinus tract or fistula at the time of surgery.

Movement of the mass with deglutition and tongue protrusion is suggestive but not 100% sensitive or specific for a thyroglossal duct cyst (TGDC).

If the mass is infected, a fine-needle aspiration can be performed to obtain a culture to direct antibiotic therapy; however, if too much fluid is aspirated, future dissection may be more difficult.

A study by Begbie et al indicated that frozen-section examination is more sensitive than fine-needle aspiration cytology (100% vs 75%, respectively) in detecting branchial cleft cysts.[9]

If the cyst is infected, treatment with an antibiotic is indicated before planning surgical excision. Complete resolution of inflammation allows for an easier and safer dissection.

Appropriate intravenous antibiotics that cover upper airway pathogens include ampicillin and sulbactam (Unasyn), clindamycin, and several other drugs. Oral antibiotics can be used after the infection has improved greatly on intravenous antibiotics and for minimally infected lesions. Appropriate oral antibiotics include amoxicillin (Augmentin), clindamycin, and several other agents.

Base the final choice of antibiotics for both intravenous treatment and oral treatment on culture and sensitivity results; therefore, needle aspiration of an acutely infected cyst early in the course of treatment is often helpful.

Macrocystic lymphatic malformations have been shown to be responsive to the sclerotherapy agent OK-432. OK-432 is a biologic preparation of lyophilized powder containing Streptococcus pyogens (group A streptococci) treated with benzylpenicillin potassium. Research with OK-432 is ongoing, but several authors have reported complete or substantial response with 4 injections of this agent given 6-8 weeks apart. Patients with microcystic disease did not respond to this treatment.

Complete surgical excision is the goal when treating branchial cleft anomalies and thyroglossal duct cysts (TGDCs). Unless dangerous compromise of the aerodigestive tract is present, avoid incision and drainage procedures. These procedures often obscure planes and make future complete surgical excision more difficult.

A study by Chung et al indicated that in the treatment of TGDCs, ethanol ablation has a higher rate of treatment failure than does surgery but results in fewer complications. According to the study, the treatment failure rate for ethanol ablation was 19.6%, compared with 2.4% for whole surgery and 1.2% for the Sistrunk operation. However, ethanol ablation had a complication rate of 1.8%, versus 10.0% for whole surgery and 10.2% for the Sistrunk operation.[10]

Surgical excision is an excellent option for lymphatic malformations that can be removed without sacrificing important adjacent structures. However, lymphangiomas and cystic hygromas frequently involve adjacent structures, which can lead to high complication rates. Infrahyoid lymphatic malformations without mediastinal involvement have been shown to have the most favorable outcome with surgical excision.

See Medical therapy.

First branchial anomalies

Excise branchial cleft anomalies under general anesthesia. Avoidance of paralytic agents by the anesthesia team is necessary in order to identify and dissect out the facial nerve. A parotidectomy incision is made with incorporation of an ellipse of skin around any prior surgical scars or sinus and fistula tracts. An s-shaped parotidectomy incision starting in the preauricular crease and extending under the mandible is appropriate.

When operating on younger children, be aware that the typical cartilaginous pointer and styloid process landmarks often are not present or are poorly developed. In these cases, the facial nerve is just deep to the parotid fascia; therefore, locating the nerve first in the neck is safer. The facial nerve is found in the triangle formed by the anterior border of the sternocleidomastoid muscle, the posterior belly of the digastric muscle, and the cartilage of the external auditory meatus.

Once the facial nerve is identified, the bifurcation and the upper and lower divisions are exposed completely with meticulous dissection. The sinus or fistula tract is dissected with a narrow cuff of normal tissue. Lacrimal probes and dilators can help identify and facilitate the dissection of a first branchial cleft fistula. The tract may be located either superficial or deep to the facial nerve.

If required, the freely dissected branchial cleft anomaly is passed over or under the main branches of the facial nerve. For complete removal, a small portion of the external auditory cartilaginous canal may need to be excised along with the tract. The tract rarely involves the tympanic membrane, which requires a tympanoplasty for complete removal.

Second and third branchial anomalies

A horizontal skin incision is made in a natural skin crease, incorporating any prior incisions or sinus tracts in an ellipse. Flaps are raised, paying close attention to protect the marginal mandibular branch of the facial nerve. After the inferior aspect of the cyst is dissected free, the dissection is carried superiorly along the tract. As the tract crosses over the hypoglossal nerve, bleeding is often encountered from the lingual venous plexus. When controlling this bleeding, care must be taken not to injure the hypoglossal nerve.

The tract is then followed between the internal and external carotid arteries with second arch anomalies or posterior to the internal carotid artery with third arch anomalies. If no internal opening is present, the tract can be ligated just as it passes deep to the posterior belly of the digastric muscle. A tonsillectomy may be required for complete excision of second branchial arch anomalies with an internal opening present in the tonsillar fossa. A thyroid lobectomy is required during the excision of a third branchial cleft anomaly.

If the fistula tract is long, a useful technique involves making 2 separate horizontal skin incisions. This stepladder technique, with one low cervical incision and a higher incision at the level of the hyoid bone, allows for excellent exposure without excessive trauma from heavy traction on the skin flaps. Avoid vertical skin incisions because the resultant scar is cosmetically unappealing.

Fourth branchial anomalies

Although controversy remains regarding the identification of third and fourth branchial sinuses, most authors recommend complete excision of the cyst along with the sinus tract. Verret et al reported a series of 10 patients with fourth branchial cleft anomalies who were treated with endoscopic cauterization of the sinus tract.[11] In this procedure, a direct laryngoscopy is performed and an intravenous balloon catheter, or angiocath, is passed into the sinus tract located at the apex of the pyriform sinus. The balloon is then inflated to dilate the opening of the sinus. An electrocautery ball coagulator is placed into the sinus tract opening and, with coagulation and manipulation, the tract is closed.

Thyroglossal duct cysts

The suggested surgical approach to the TGDC is the Sistrunk operation. The operation includes excision of the cyst in continuity with the mid portion of the body of the hyoid bone and a small block of muscle around the foramen cecum. The procedure is performed under general anesthesia with a shoulder roll in place.

A skin incision is made in a natural skin crease near the cyst; any previous incisions or sinus tracts are included in the ellipse. A superior flap is raised to the level of the hyoid bone, and an inferior flap is raised until the inferior aspect of the cyst is identified. The strap muscles are separated, and the cyst is dissected from the surrounding structures until it is attached only to the hyoid bone superiorly. The body of the hyoid bone is skeletonized and then transected on each side of the pedicle. A curved retractor is placed transorally, which facilitates excision of the tract up to the base of tongue with the inclusion of a 5-10 mm core of muscle.

A Penrose drain, or suction drain, is placed in the incision, and the neck is wrapped with a pressure dressing at the end of the operation. On postoperative day 1, the dressing can be removed and the patient is usually sent home later that day, after tolerating an oral diet. Some patients are discharged home on the same day as the surgery.

Patients are usually seen in the office 2-3 weeks after the procedure to make sure that the wound is well healed and that no problems are encountered.

Complications from operating on a branchial cleft or thyroglossal duct anomaly include infection, hematoma, and recurrence.

Branchial cleft anomalies

Ideally, remove the cyst intact without entering the cystic cavity. Removing these lesions in a piecemeal manner increases the chance of leaving residual epithelial tissue and, therefore, increases the risk of recurrence. Take care also in obtaining meticulous intraoperative hemostasis.

Transient, and even permanent, injury to the facial nerve can be a complication of operating on first branchial cleft anomalies. The internal and external carotid arteries, internal jugular vein, and cranial nerves IX, X, XI, and XII all are at risk when dissecting second and third branchial cleft anomalies. The recurrent laryngeal nerve especially is at risk when dissecting along the tract of a third branchial cleft anomaly.

A retrospective study by Mattioni et al using the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database found that at least one 30-day postoperative complication, predominantly superficial surgical site infection, occurred in 45 out of 895 patients (5.0%) who underwent pediatric branchial cleft cyst excision. The 30-day complication rate was higher in patients with a history of developmental delay.[12]

Similarly, a study by Moroco et al using the pediatric and adult NSQIP databases found postoperative complications associated with branchial cleft cyst excision to be relatively uncommon in adults and children. Complication rates of 3.9% and less than 1% were reported in children and adults, respectively, while readmission rates were 1.1% and 1.2%, respectively. The evidence also indicated that in adults, smoking status significantly impacts postoperative complications (odds ratio 6.25).[13]

Thyroglossal duct cysts

The greatest risk of recurrence of a thyroglossal duct cyst (TGDC) is associated with failure to follow the surgical principles described by Sistrunk. For example, a study by Danau et al indicated that in pediatric patients with TGDCs, there is less risk of recurrence in those treated with the Sistrunk operation than in individuals who undergo treatment with only simple excision or marsupialization. With recurrence found in 12 out of 104 cases (11.5%), five recurrences (41.7%) developed patients who had not undergone the Sistrunk procedure.[14]

Rates of recurrence are also increased when a TGDC is ruptured during dissection. Previous infection, prior incision and drainage procedures, and adherence of the cyst to the skin all are associated with an increased rate of rupture with dissection. Wound infections can also occur when the cyst is ruptured or when the pharynx is entered.

With no history of infection or prior surgery, the recurrence rate after operating on a branchial cleft anomaly is approximately 3%. The recurrence rate increases to approximately 20% after prior unsuccessful attempts at surgical removal. The recurrence rate associated with simple excision of a thyroglossal duct cyst (TGDC) is approximately 50%. The recurrence rate with a formal Sistrunk procedure is approximately 5%.

Branchial cleft anomalies

The risk of malignancy arising from a branchial cleft cyst has been a topic of debate for years. Von Volkmann first described branchial cleft cyst carcinoma in 1882; however, the consensus today is that branchial cleft carcinoma rarely, if ever, occurs.

In 1950, Martin et al reviewed the literature and rejected all of the previous reports of branchial cleft cyst carcinoma.[15] They proposed that most of these patients had a metastatic squamous cell carcinoma cyst from an undiagnosed primary lesion. Before diagnosing a patient with a branchial cleft cystic carcinoma, the patient must meet the following criteria:

• The cystic tumor must be located along the line from anterior to the tragus, downward along the anterior border of the sternocleidomastoid muscle, to the clavicle.

• Histologic examination reveals cancer developing in the wall of an epithelial-lined cyst. Transition from benign cyst epithelium to squamous cell carcinoma along the wall of the cystic cavity is evident.

• The patient must have survived at least 5 years without developing any other lesions that could possibly be the primary tumor.

In 1979, Batsakis estimated that, even when including questionable cases of branchial cleft carcinoma, the incidence of branchial cleft carcinoma is approximately 0.3% of all malignant head and neck neoplasms.[16] On the other hand, metastatic cystic lymph nodes are quite common; therefore, patients with cystic carcinoma in the neck are assumed to have carcinoma metastatic to cervical lymph nodes from an unknown primary site.

Thyroglossal duct cysts

Literature regarding carcinoma arising from a thyroglossal duct cyst (TGDC) does not share the same controversy as reports of branchial cleft cyst carcinoma. In 1925, Ashurst and White first reported a case of carcinoma arising in a thyroglossal duct remnant.[17] Since that time, more than 100 cases have been reported, with the overall incidence of TGDC cancer being less than 1%. For unclear reasons, cancer in a TGDC is more common in females than in males. The diagnosis of carcinoma arising in a TGDC is usually made histologically only after the tumor has been removed.