Branchial cleft anomalies are a common cause of congenital neck masses and can present as a cyst, sinus, or fistula. A comprehensive understanding of the embryologic basis of these anomalies aids in diagnosis and surgical excision. Fistulas tend to present at an earlier age than sinuses or cysts, with most lesions presenting as either a neck mass, draining sinus, or recurrent infections. The eventual management of each is complete surgical excision, which is curative. A history of recurrent preoperative infections leads to a higher rate of recurrence.
Key points
- •
Thorough knowledge of the embryology of branchial arch derivatives is essential for accurate diagnosis and surgical management of these anomalies.
- •
A history of preauricular infections and otorrhea with a normal tympanic membrane should raise suspicion of a first branchial arch anomaly.
- •
Always consider the diagnosis of a cystic metastasis in the differential of a presumed branchial cleft anomaly in an adult.
- •
CT scan with contrast, MRI, fistulograms, and ultrasound have all been used to aid in the diagnosis of congenital neck masses and predict the intraoperative findings before surgical excision.
- •
When managing first arch anomalies, be prepared to identify the facial nerve and perform a superficial or total parotidectomy (ie, informed consent, adequate sterile preparation, nerve monitoring, parotid instruments).
- •
Direct laryngoscopy and attention to the pyriform sinus with palpation on the ipsilateral neck can aid in pre-excision diagnosis of a third or fourth branchial cleft fistula.
| BCA | Branchial cleft anomalies |
| CT | Computed tomography |
| MRI | Magnetic resonance imaging |
| SCM | Sternocleidomastoid muscle |
Introduction
Branchial or pharyngeal cleft anomalies are an important diagnostic consideration in pediatric neck pathology. They represent the most common congenital lateral neck mass, and are second only to thyroglossal duct cysts when all cervical sites are included. These anomalies can occur as a cyst (epithelial-lined structure that lacks a connection to the skin or pharynx), a sinus (connecting either the skin or pharynx to a blind pouch in the neck), or a fistula (an open tract connecting the skin and pharynx).
The term branchial is derived from the Greek term “branchia,” meaning gills. This terminology stems from the transient structures that appear from the fourth to the seventh week of gestation on the lateral aspects of the developing fetus. They are thought to be phylogenetically related to gill slits in amphibians. The branchial or pharyngeal apparatus is composed of mesodermal arches that appear on the superior-lateral aspects of the developing fetus. These arches are separated by external clefts or grooves (found on the epithelial surface between each arch and, with the exception of the first cleft, obliterate during normal development) and internal pouches (endodermal-derived elements). Each of these numbered arches develops into an associated nerve, blood vessel, and muscle group ( Table 1 ). Aberrant development of these structures or incomplete obliteration of the clefts and grooves that divide them can lead to a variety of different anomalies. Here we present an overview of these anomalies and discuss their cause, presentation, and treatment.
| Arch | Skeletal | Nerve | Muscles | Artery | Pouch | Cleft |
|---|---|---|---|---|---|---|
| First (mandibular arch) |
| Trigeminal (V) | Muscles of mastication Tensor tympani Tensor palatini Mylohyoid Anterior belly of digastric | Maxillary | Eustachian tube Middle ear | External auditory canal |
| Second (hyoid arch) |
| Facial (VII) | Muscles of facial expression Stapedius Stylohyoid Posterior belly of digastric | Stapedial (normally obliterates) | Lining (crypts) of palatine tonsils | Obliterates |
| Third | Hyoid bone-greater horn, lower half of body | Glossopharyngeal (IX) | Stylopharyngeus | Common/internal carotid | Inferior parathyroid gland Thymus | Obliterates |
| Fourth | Thyroid cartilage Epiglottic cartilage | Vagus (X) Superior laryngeal nerve | Cricothyroid All muscles of pharynx (except stylopharyngeus) All muscles of soft palate (except tensor palatini) | Aortic arch and subclavian | Superior parathyroid gland C-cells of Thyroid | Obliterates |
| Fifth arch is transient and no structures are derived from this arch in mammals | ||||||
| Sixth | Cricoid cartilage Arytenoid complex | Vagus (X) Recurrent laryngeal nerve | Intrinsic muscles of the larynx except the cricothyroid | Pulmonary arteries and ductus arteriosis | — | Obliterates |
Introduction
Branchial or pharyngeal cleft anomalies are an important diagnostic consideration in pediatric neck pathology. They represent the most common congenital lateral neck mass, and are second only to thyroglossal duct cysts when all cervical sites are included. These anomalies can occur as a cyst (epithelial-lined structure that lacks a connection to the skin or pharynx), a sinus (connecting either the skin or pharynx to a blind pouch in the neck), or a fistula (an open tract connecting the skin and pharynx).
The term branchial is derived from the Greek term “branchia,” meaning gills. This terminology stems from the transient structures that appear from the fourth to the seventh week of gestation on the lateral aspects of the developing fetus. They are thought to be phylogenetically related to gill slits in amphibians. The branchial or pharyngeal apparatus is composed of mesodermal arches that appear on the superior-lateral aspects of the developing fetus. These arches are separated by external clefts or grooves (found on the epithelial surface between each arch and, with the exception of the first cleft, obliterate during normal development) and internal pouches (endodermal-derived elements). Each of these numbered arches develops into an associated nerve, blood vessel, and muscle group ( Table 1 ). Aberrant development of these structures or incomplete obliteration of the clefts and grooves that divide them can lead to a variety of different anomalies. Here we present an overview of these anomalies and discuss their cause, presentation, and treatment.
| Arch | Skeletal | Nerve | Muscles | Artery | Pouch | Cleft |
|---|---|---|---|---|---|---|
| First (mandibular arch) |
| Trigeminal (V) | Muscles of mastication Tensor tympani Tensor palatini Mylohyoid Anterior belly of digastric | Maxillary | Eustachian tube Middle ear | External auditory canal |
| Second (hyoid arch) |
| Facial (VII) | Muscles of facial expression Stapedius Stylohyoid Posterior belly of digastric | Stapedial (normally obliterates) | Lining (crypts) of palatine tonsils | Obliterates |
| Third | Hyoid bone-greater horn, lower half of body | Glossopharyngeal (IX) | Stylopharyngeus | Common/internal carotid | Inferior parathyroid gland Thymus | Obliterates |
| Fourth | Thyroid cartilage Epiglottic cartilage | Vagus (X) Superior laryngeal nerve | Cricothyroid All muscles of pharynx (except stylopharyngeus) All muscles of soft palate (except tensor palatini) | Aortic arch and subclavian | Superior parathyroid gland C-cells of Thyroid | Obliterates |
| Fifth arch is transient and no structures are derived from this arch in mammals | ||||||
| Sixth | Cricoid cartilage Arytenoid complex | Vagus (X) Recurrent laryngeal nerve | Intrinsic muscles of the larynx except the cricothyroid | Pulmonary arteries and ductus arteriosis | — | Obliterates |
Relevant anatomy and pathophysiology
As with any congenital condition, a complete understanding of the normal developmental process is critical to understanding the pathology that results when this process is interrupted in some way. During fetal development, six paired outpouchings (arches) originate on the ventrolateral aspect of the developing embryonic head and join in the midline. Each arch is separated externally by grooves or clefts, which are lined with ectodermal tissue. The internal surface of the arches is separated by pouches, which are lined by endodermal tissue. The individual arches themselves are composed of mesodermal tissue, which develops into an artery, nerve, muscular, and cartilageous elements (see Table 1 ). As the fetus matures, these elements form well-defined anatomic structures that are present at birth.
Initially during development the endodermal and ectodermal linings come into close contact, further separating the arches. As the fetus matures, most of the external cleft and internal pouches are obliterated as the adjacent arches subsequently fuse (see Table 1 ). Branchial cleft anomalies (BCAs) result from incomplete obliteration of the associated cleft or pouch during this process. The resulting cyst, sinus, or fistula is based on the specific arch and degree of obliteration that is completed. This embryologic basis means that each anomaly courses inferior to the anatomic derivatives of its associated arch and superior to all derivatives of the next arch (see Table 1 ). This knowledge allows the surgeon to identify correctly the associated arch and predict its tract intraoperatively. Depending on the arch of origin, these anomalies can present as a mass or draining tract anywhere from the preauricular skin down to the clavicle with the external opening at the anterior border of the sternocleidomastoid muscle (SCM).
Clinical presentation and examination
Many symptoms of BCA are nonspecific, including neck swelling, recurrent infections, and drainage. Because of the nonspecific nature of many of these complaints, most patients present initially to their primary care physician or pediatrician. Once the diagnosis is suspected, the surgeon is consulted. Only a small minority of these are discovered incidentally, either by physical examination or during imaging for a nonrelated complaint. The clinical presentation of each lesion ultimately depends on the arch involved and the exact anomaly present.
Most patients with a cyst (no connection to the external skin or pharynx) present with a firm, nontender mass, usually in the anterior cervical triangle anywhere from the preauricular region to the supraclavicular fossa. If the cyst is large, dysphagia, dyspnea, and stridor can be present. Infection or hemorrhage into a cyst can lead to an abrupt increase in size, worsening pain, or abscess formation. When a sinus connecting to the pharynx is present, these tend to present with recurrent infections. A connection to the skin can present with infections, drainage, or an external skin pit. A fistula usually presents with a draining skin pit.
Although BCAs can present at any age, most cases are diagnosed in early childhood. A 10-year review of pediatric BCAs showed that the average age of presentation was younger than 5 years with fistulas presenting at the youngest age. Sinuses and cysts tended to present at an older age. Second arch anomalies were the most common followed by first arch anomalies. Overall there is no predilection for sex (male or female) or side (left or right); however, complete second branchial cleft fistulas have recently been shown to be more common on the right, whereas third arch anomalies tend to affect the left. Most occur spontaneously; however, a minority is associated with a syndrome (most commonly branchio-oto-renal syndrome, which often presents with bilateral BCA, bilateral preauricular pits, and renal anomalies).
First Branchial Cleft Anomalies
Periauricular pits, sinuses, and tags are the most common first branchial arch anomalies. These lesions result from aberrant development of the first three hillocks of His, which form from the dorsal aspect of the first branchial arch and contribute to formation of the auricle. They do not involve the first branchial cleft and therefore are not true BCAs; however, it is important to know and recognize the distinction between these two conditions because preauricular pits are a common incidental finding in pediatric patients and often do not require surgical management. Preauricular pits and tags usually occur in the preauricular skin anterior to the tragus or the ascending rim of the helix. Although preauricular tags mostly present only cosmetic concerns, preauricular sinuses can have a history of drainage at the site of a skin pit. Recurrent infection with cellulitis and abscess formation also occurs, although most are asymptomatic. Physical examination should pay particular attention to the site of the lesion or skin opening and the presence of any signs of infection (erythema, tenderness, fluctuance, or induration of surrounding structures). The ear canal should be examined carefully to ensure that there are no signs of connection or duplication, which would represent a true first cleft anomaly. If the patient tolerates, gentle probing of the tract can give the surgeon valuable information about the extent of the anomaly.
First BCAs, which exclude pits and tags, are rare and account for less than 20% of all BCAs. The epithelial component of these anomalies is found above the hyoid bone with a tract coursing through the parotid gland. Because the gland and facial nerve are developing at the same time as the tract is obliterating, the relationship of the tract to the facial nerve is variable in these anomalies. This lesion can course either superficial or deep to the main trunk or even travel between nerve branches. If an internal communication is present, the opening courses into the external auditory canal or middle ear cleft.
Because of their location, first branchial cleft remnants can present with recurrent preauricular or upper neck swelling. If they rupture, a draining sinus often results. One should be suspicious of a first branchial anomaly when a child presents with recurrent otorrhea without evidence of middle ear disease or significant canal inflammation. The cysts may occur in the parotid gland itself thus leading to the misdiagnosis of salivary pathology.
Several authors have attempted to classify first BCAs; however, the most widely used scheme was published by Work in 1972. He proposed a system of dividing first branchial anomalies according to their embryologic derivative. Type I anomalies consisted only of ectodermal elements. In contradistinction type II anomalies consisted of ectodermal and mesodermal elements. This method adds a histologic component to the traditional anatomic classification. Several authors have proposed revisions of Work’s classification. Belenky and Medina proposed a modification where a type 1 anomaly is a preauricular cyst or sinus, which courses lateral or superior to the facial nerve and terminates without an opening in the external auditory canal. A type II anomaly can be a cyst, sinus, or fistula where the tract starts near the angle of the mandible and tracts superior medially to join or open into the cartilaginous external auditory canal. This tract can have a variable relationship to the facial nerve. This classification is purely anatomic and removes the histologic basis and is preferred by some authors.
However one classifies the anomaly, the relationship of the lesion or tract to the facial nerve is a critically important one and there is not currently an accurate way for the clinician to determine this relationship before surgery. Given this, if a surgeon is not prepared or capable of identifying, preserving, and protecting the facial nerve during surgery, then no attempt should be made at removal of first BCAs.
Second Branchial Cleft Anomalies
Most (70%–90%) BCAs originate from the second cleft. The skin opening of a second BCA is lower in the neck at the anterior border of SCM. Clinically, these anomalies have much in common with some third arch anomalies; however, the diagnosis is made clear during surgical excision. The tract of the second cleft anomaly starts in the tonsillar fossa, courses inferior-laterally, and travels superior-lateral to the glossopharyngeal and hypoglossal nerves. The tract courses between the internal and external carotid arteries and terminates at a skin opening anterior to the SCM. Cleft anomalies can present anywhere along this tract.
Cysts are the most common second BCA, followed by sinuses and then fistulas. Second branchial cleft cysts present most commonly with a cystic neck mass located deep to the SCM. When the anomaly involves a tract (ie, sinus or fistula), the most common presenting complaint is an external skin opening with drainage, followed by recurrent infections. Abscess formation can also occur, and in patients with a history of infection, they tend to be recurrent in nature.
Third Branchial Cleft Anomalies
Third BCAs are rare but can have many similarities with second arch anomalies. Cysts again present with a mass deep to the SCM, as with second arch anomalies. The skin opening again is low in the lateral neck anterior to the SCM. These tend to occur on the left side of the neck. The theoretic tract of a third BCA originates in the apex of the piriform sinus, pierces the thyrohyoid membrane, and travels inferior and posterior to the glossopharyngeal nerve and superior to the hypoglossal nerve. The tract courses posterior to the internal carotid artery and exits the skin just anterior to the SCM.
A key clinical piece of information that can lead to suspicion of a third arch anomaly is the close relation of these arch elements to the thyroid gland. Inflammation of these anomalies can often lead to recurrent bouts of thyroiditis. Furthermore, an abscess in the neck located within or surrounding the thyroid gland should raise suspicion of a third arch anomaly. Although not always typical in second branchial cleft sinuses, a neck abscess is typical of a third branchial cleft sinus. The connection to the dependent pyriform sinus leads to frequent contamination by oropharyngeal secretions in third branchial cleft sinuses, whereas the lateral location of the tonsillar crypts without dependent drainage makes this rarer in second cleft anomalies.
Cervical Thymic Anomalies
Cervical thymic anomalies are themselves branchial arch anomalies because of their embryologic derivative from the third arch (see Table 1 ). Although ectopic cervical thymic tissue can be seen anywhere along the course of the thymic descent, this condition is exceedingly rare. Cervical thymic cysts are more common than ectopic thymic tissue but remain a rare presentation of congenital neck lesions. A review of 20 cases at Cincinnati Children’s Hospital revealed the most common presentation of cervical thymic anomalies is a mass with associated compressive symptoms. There was a predilection for these anomalies on the left side; however, midline and right-sided anomalies were seen. Most patients were male with age ranges from 1 to 16 years. An association with lymphoma or its treatment has been suggested but this condition is so rare that finding consistent associations can be difficult.
Fourth Branchial Cleft Anomalies
Fourth BCAs are without question the rarest with few having been described in the literature. These cysts and sinuses present with recurrent lower neck or upper chest infections. Thyroiditis also can be seen and these patients have frequently been misdiagnosed and had inappropriate surgical interventions. Although cysts and sinuses have been reported, a fourth branchial cleft fistula is thought to have never occurred because of the long tortuous course that this anomaly would have to take from the pyriform sinus to the skin. The theoretic path of this tract originates in the pyriform sinus and courses inferiorly, deep to the superior laryngeal nerve and superficial to the recurrent laryngeal nerve and tracts inferiorly to wrap around the aortic arch on the left and subclavian artery on the right, then ascends superiorly, posterior to the carotid artery and attaches to the skin low in the neck anterior to the SCM.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
