Fourth branchial pouch sinus: A report of 7 cases and review of the literature.
A fourth branchial pouch sinus often manifests quite late in life as a recurrent neck abscess, suppurative thyroiditis, or pseudothyroiditis. Demonstration of the sinus opening in the piriform fossa by hypopharyngoscopy in combination with ultrasonography of the neck provides adequate information to justify proceeding to surgery. The sinus tract usually courses through the thyroid cartilage. The most effective treatment is surgical excision of the tract up to the piriform fossa through the cartilage. This procedure is associated with very low complication and recurrence rates. A fourth branchial pouch sinus is an uncommon condition. Even so, it is still underdiagnosed as a result of poor awareness of its existence by medical practitioners, including otolaryngologists. Part of the reason is a lack of adequate coverage of this topic in otolaryngology and surgery textbooks. In this article, we add to the literature by describing our experience with 7 patients--4 males and 3 females, aged 5 to 45 years (mean: 25.6)--who were diagnosed with a fourth branchial pouch sinus over a 6-year period. The diagnosis was confirmed by identifying the sinus opening at the apex of the piriform sinus during hypopharyngoscopy. Definitive treatment consisted of surgical exploration of the neck and excision of the tract.
Branchial cleft anomalies are not uncommon in clinical practice. Most of these (~95%) originate in the second branchial cleft. (1) The remainder originate in the first, third, or fourth clefts. (2)
Fourth branchial cleft anomalies are rarely encountered, poorly understood, and often misdiagnosed. As a result, patients with this condition often undergo multiple consultations, referrals, and interventions before a definitive diagnosis is made and treatment instituted. The reason for this is a lack of awareness about this condition among the medical community--specifically, among otolaryngologists, general surgeons, and pediatricians, who are generally the first to attend these patients after referral by a general practitioner.
Fourth branchial pouch anomalies clinically manifest as a recurrent neck abscess, suppurative thyroiditis, or pseudothyroiditis. (3) They are almost always located on the left side of the midline in the anterior part of the neck. They present as a sinus tract with a proximal opening in the floor of the piriform fossa; from there they extend upward for various distances in the neck.
In this article, we report our experience with 7 cases of fourth branchial pouch sinus, and we discuss their presentation, diagnosis, and treatment. We also discuss the possible reasons for delays in establishing a definitive diagnosis, and we offer our suggestions for making an early diagnosis.
Patients and methods
Patients. Over a period of 6 years at our institution, 7 patients--4 males and 3 females--were diagnosed with and operated on for a fourth branchial pouch sinus by the team of authors. For this study, we retrieved their medical records and compiled, in addition to the demographic data, information on their patient profile, their age at the onset of symptoms, the type of symptoms, the interval between symptom onset and the definitive diagnosis, the side of the sinus, the number of symptomatic episodes, and the number and type of previous surgical interventions performed before the definitive diagnosis was established.
Surgical procedure. All patients were treated under general anesthesia with surgical excision of the sinus tract through a neck incision. In the operating room, patients were placed in the supine position with the neck extended. An incision was made in equal lengths on both sides of the midline in a transverse neck crease roughly corresponding to the lower end of the lesion. Subplatysmal flaps were raised superiorly and inferiorly for adequate exposure. Superiorly, the exposure extended to the upper border of the thyroid cartilage. The strap muscles were retracted, and the upper pole of the thyroid lobe was exposed.
All the sinus tracts ended roughly at the upper pole of the thyroid gland. The sinus tract was identified and carefully dissected out. The recurrent laryngeal nerve was dissected if the sinus tract extended below the level of the cricothyroid joint. The superior laryngeal nerve was dissected and preserved whenever possible. Thyroid lobectomy was not required in any of our cases because the tract could be dissected free off the thyroid gland in all of them. The tract was then traced superiorly.
In all cases, the tract was found to pierce the thyroid cartilage at its lower end before opening into the piriform fossa. Therefore, a small sliver of thyroid cartilage was cut from the posterior border of the thyroid ala to trace the sinus tract up to the floor of the piriform fossa (figure 1). The tract was then excised as close to the piriform fossa as possible, and the stump was ligated with nonabsorbable sutures. The wound was then closed in layers. No drains were required.
Postoperative recovery was uneventful in all patients, and nonsteroidal anti-inflammatory drugs were the only necessary prescribed medications.
Patients' age at the onset of symptoms ranged from 3 to 40 years (mean: 20.3), and their age at diagnosis ranged from 5 to 45 years (mean: 25.6) (table 1).
The most common manifestation was recurrent neck abscess, which was seen in 5 of the 7 patients and which required multiple drainings. Recurrent thyroiditis or pseudothyroiditis was seen in 4 patients. One patient (patient 6) also had a pharyngeal fistula in addition to a recurrent abscess and thyroiditis; the fistula developed after she had undergone a total thyroidectomy at another institution for the treatment of suspected medullary thyroid cancer (table 1).
In all cases, the definitive diagnosis was made by viewing the sinus tract opening on the floor of the ipsilateral piriform sinus near its apex (figure 2). In the first 4 patients we tested, a barium swallow examination failed to demonstrate the sinus tract, even after the Valsalva maneuver, so we decided against administering a barium swallow test to the succeeding 3 patients.
Computed tomography (CT) was obtained in patients 1,2,3, and 4, followed by ultrasonography of the neck; both demonstrated a hypodense area in relation to the thyroid gland. Since CT provided no information beyond what we saw on ultrasonography, we did not obtain CT in patients 5, 6, and 7, and we relied on just the ultrasonographic findings.
As described, definitive treatment entailed surgical exploration of the neck and excision of the tract. The tracts were easily dissected off the thyroid lobes, and thyroidectomy of any description was not required in any patient. Electrocautery was attempted in 3 patients (patients 1,6, and 7), but it was unsuccessful in resolving the symptoms.
Follow-up ranged from 2 months to 6 years. No patient experienced any significant postoperative complications or recurrence (table 2).
Of the 7 patients, only 2 demonstrated the presence of lining epithelium, but all 7 exhibited inflammatory tissue and a tract lumen. The lining epithelium in both cases was stratified squamous epithelium; a focal presence of columnar epithelium was also seen in 1 of these 2 patients. However, even in the absence of any epithelial lining, the presence of a lumen and the preoperative demonstration of a tract opening in the piriform sinus left no doubt about the diagnosis.
Although it is theoretically possible, the presence of a complete fourth branchial cleft or pouch fistula has never been demonstrated. It generally presents as a sinus with a proximal opening in the apex of the piriform fossa and with the distal end extending to any point along the theoretical extent of the tract--that is, beginning at the piriform fossa, passing between the thyroid (fourth arch) and cricoid (fifth arch) cartilages, descending between the superior laryngeal nerve and the cricothyroid muscle (fourth arch), and thereafter extending between the trachea and the recurrent laryngeal nerve.
The tract then loops around the aortic arch on the left side and around the subclavian artery on the right side and rises in the cervical area posterior to the common carotid artery. Then it loops over the hypoglossal nerve and finally descends and opens on the skin of the lower neck along the anterior border of the sternocleidomastoid muscle. (4)
Based on the difference between the theoretical course and the actual course of the sinus tract, Thomas et al suggested that the branchial sinuses arising from the piriform sinuses do not originate in the true third or fourth arch pouches but that they are sinuses arising from a patent thymopharyngeal duct. (5) None of the fistulas described in their report were congenital; all were acquired secondary to infection and abscess formation, which was followed by spontaneous rupture or surgical drainage. The lone patient in our series who presented with a fistula had developed it secondary to a thyroidectomy performed at another hospital.
Lu et al suggested that there could be three different emerging pathways for the sinus tract from the piriform fossa. (6) The tract could emerge by penetrating either the thyroid cartilage near the inferior cornu, the inferior constrictor muscle of the pharynx, or the cricothyroid membrane as it emerges from the pharynx. In our series, all seven tracts emerged by penetrating the thyroid cartilage. This probably indicates that this is the most common course.
A third branchial pouch sinus is similar to a fourth branchial pouch sinus in its course and presentation. The difference is that the third pouch sinus opens in the cranial part of the piriform sinus, while the fourth opens more caudally at the apex of the piriform fossa. (7) The third pouch sinus then courses superiorly through the thyrohyoid membrane cranial to the superior laryngeal nerve, posterior to the carotid vessels, and deep to the sternocleidomastoid muscle. (4) In our series, all the sinus tracts were located caudal to the superior laryngeal nerve, and all opened at the apex of the piriform sinus.
A fourth branchial pouch sinus, like most congenital conditions, is generally believed to manifest as symptoms during the first or second decade of life. (8,9) In our series, however, only 3 of the 7 patients experienced an onset of symptoms within the first decade. In the other 4 patients, the initial symptoms manifested late--at the age of 20, 28, 37, and 40 years.
By far, most fourth branchial pouch sinuses occur on the left side, probably as a result of the asymmetry in vascular development in this arch. (1) They are rarely seen on the right side, and there are only occasional reports of bilateral sinuses. (10) In our series, only 1 of the 7 was located on the right side.
The most common presentation is recurrent deep neck infections, (3) followed by thyroiditis-like features (pseudothyroiditis). (11) Two uncommon presentations that have been reported were stridor in a neonate (12) and suspected esophageal perforation in a 14-year-old boy. (13) Our study yielded similar findings, although we had the 1 case of iatrogenic fistula.
A fourth branchial pouch sinus should be high on the list of differential diagnoses for patients with recurrent thyroiditis or recurrent neck abscess, especially on the left side. The recommended investigations for confirming the diagnosis include a barium swallow examination, sonography with a Valsalva maneuver, fiberoptic laryngoscopy, CT, magnetic resonance imaging (MRI), and hypopharyngoscopy under general anesthesia.
In our series, the most definitive diagnosis was made by viewing the sinus tract opening on the floor of the ipsilateral piriform sinus near its apex. Barium swallow examination failed to demonstrate the sinus tract, even after the Valsalva maneuver in our first 4 patients, so we decided against performing this test in the 3 patients who presented later. The reason for the low yield of barium swallow skiagrams is probably because they require a quiescence of inflammation of the tract for the entry of the barium contrast into the sinus.
CT was performed in our first 4 patients, and it demonstrated a hypodense area in relation to the thyroid gland. Ultrasonography of the neck was also performed on these 4 patients, and the findings were similar to those of CT. Since CT provided no additional information beyond what we saw on ultrasonography, we decided that it was unnecessary for the final 3 patients, and we used only the ultrasonographic findings. MRI was not available at our institution.
We believe that the demonstration of the sinus opening in the apex of the piriform sinus with a flexible fiberoptic laryngoscope or bronchoscope or with an upper gastrointestinal endoscope is a simple, highly sensitive, and highly specific procedure for confirming the diagnosis of a fourth branchial pouch sinus. We also conclude that ultrasonography of the neck performed by an experienced and competent radiologist is sufficient to identify the extent of the sinus tract. The two procedures together provide us with adequate information with which to proceed to surgery. Other radiologic investigations yielded little additional information over and above what these two procedures did.
The most noteworthy finding of our study was that almost all of our patients presented with two or more episodes of pseudothyroiditis or abscess in the neck that required multiple drainings. One of our patients (patient 6) had undergone five previous surgical interventions at different hospitals, including a total thyroidectomy that led to the development of a nonhealing fistula in her neck, and yet a precise diagnosis was not made.
In an attempt to understand the low level of suspicion among physicians when it comes to recognizing and diagnosing fourth branchial pouch sinuses, we reviewed the world literature as available on PubMed. We found that the interval between the first appearance of symptoms and the final diagnosis ranged from 2 to 10 years, (14,15) excluding neonatal presentations (12,16) and incidental presentations. (13) In a case published in 2012, a young boy experienced 10 episodes of neck abscess during a 10-year span, and he had undergone seven surgical interventions before a diagnosis was finally reached. (6) This fact is astonishing given that more than 100 cases of fourth branchial sinus have been indexed on PubMed, with the first case having been reported more than 40 years ago. (2)
We also reviewed 6 reference books on otorhinolaryngology and head and neck surgery and found only 1 that contained a complete description, which consisted of 27 lines of text. (17) We found 3 to 8 lines of text tucked away in four other books. (18-21) We also checked 3 reference books in surgery along with 10 different textbooks used by undergraduate medical students in otorhinolaryngology, and none of them contained any mention of this condition. We believe that the description of this condition should not be limited to articles in peer-reviewed journals, but should be included in detail in all future textbooks, for undergraduates as well as for postgraduates, to raise the level of awareness of this condition.
The definitive treatment for a fourth branchial pouch sinus is an excision of the tract via a neck incision, sometimes accompanied byahemithyroidectomy, (6,9) an endoscopic transpharyngeal excision with a C[0.sub.2] laser, (22) chemocauterization with 10% trichloroacetic acid, (23) endoscopic monopolar diathermy, (24) or even KTP-laser-assisted endoscopic tissue fibrin glue biocauterization. (25) We managed all of our patients with surgical excision of the tract through a neck incision. In all cases, we could dissect the sinus tract from the thyroid gland and surrounding tissues, and therefore we did not have to perform a thyroid lobectomy in any patient.
The sinus tract is said to be lined with columnar epithelium. In our series, most patients exhibited a denudation of the epithelial lining, owing to recurrent inflammation. Two of our patients had a stratified squamous epithelium. This might have been attributable to a metaplastic change in the normal columnar epithelial lining of the branchial sinus secondary to recurrent inflammation. (3,26) In such a circumstance, histopathology provides little clue as to the diagnosis of a fourth branchial pouch sinus.
In conclusion, a fourth branchial pouch sinus is an uncommon yet underdiagnosed condition. Awareness of its existence is low, and thus so is a suspicion for it among medical practitioners, including otolaryngologists. The problem is compounded by a lack of adequate coverage of this topic in otorhinolaryngology and surgery textbooks, a deficiency that needs to be corrected in the future.
The most common presentation of this condition is a recurrent neck abscess on the left side. Symptoms often manifest quite late in life, unlike the case with most congenital sinuses, fistulae, and cysts.
A fourth branchial pouch sinus is best diagnosed by demonstration of the sinus opening in the piriform fossa. Hypopharyngoscopy in combination with ultrasonography of the neck provides adequate information with which to proceed to surgery.
The tract most commonly courses through the thyroid cartilage. Surgical excision of the tract up to the piriform fossa through the cartilage is the most effective treatment, and it is associated with very low complication and recurrence rates.
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Indranil Pal, MS; Saumitra Kumar, MS; Ankur Mukherjee, MS, DNB; Bibhas Mondai, MS; Anindita Sinha Babu, MD
From the Department of Otorhinolaryngology (Dr. Pal, Dr. Kumar, Dr. Mukherjee, and Dr. Mondai) and the Department of Pathology (Dr. Babu), College of Medicine & JNM Hospital, West Bengal University of Health Sciences, Kalyani, Nadia, West Bengal, India.
Corresponding author: Dr. Indranil Pal, Department of Otorhinolaryngology, College of Medicine & JNM Hospital, West Bengal University of Health Sciences, Kalyani, Nadia, West Bengal 741235, India. Email: firstname.lastname@example.org
Caption: Figure 1. The tract of the right-sided fourth branchial pouch sinus in patient 5 extends behind the ala of the thyroid cartilage and enters the apex of the piriform sinus. A sliver of thyroid cartilage was excised to trace the tract into the piriform fossa (SCM = sternocleidomastoid muscle).
Caption: Figure 2. Endoscopic views show the proximal openings of sinus tracts at the apex of the right piriform fossa (A) and the left piriform fossa (B).
Table 1. Clinical data obtained at presentation Sex/age at Age at Pt. presentation, onset, Symptom Side yr yr 1 M/20 20 RT Left 2 F/5 3 RNA Left 3 M/45 40 RNA Left 4 M/10 8 RNA Left 5 M/30 28 RT + RNA Right 6 F/29 6 RT + RNA + fistula Left 7 F/40 37 RT Left Symptomatic Previous Pt. episodes, n surgeries, n 1 2 0 2 4 3 3 5 2 4 3 1 5 4 3 6 6 5 7 4 3 Key: RT = recurrent thyroiditis or pseudothyroiditis; RNA = recurrent neck abscess. Table 2. Investigations, treatments, and outcomes Thyroid Vocal fold Pt. Scope findings * Site of tract exit lobectomy paralysis 1 Opening identified Thyroid cartilage Not done No 2 Opening identified Thyroid cartilage Not done No 3 Opening identified Thyroid cartilage Not done No 4 Opening identified Thyroid cartilage Not done No 5 Opening identified Thyroid cartilage Not done No 6 Opening identified Thyroid cartilage Not done No 7 Opening identified Thyroid cartilage Not done No Pt. Scope findings * Follow-up Recurrence 1 Opening identified 6 yr No 2 Opening identified 4 yr No 3 Opening identified 3 yr No 4 Opening identified 3 yr No 5 Opening identified 2 yr No 6 Opening identified 3 mo No 7 Opening identified 2 mo No * Hypopharyngoscopy.
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|Title Annotation:||ORIGINAL ARTICLE|
|Author:||Pal, Indranil; Kumar, Saumitra; Mukherjee, Ankur; Mondai, Bibhas; Babu, Anindita Sinha|
|Publication:||Ear, Nose and Throat Journal|
|Article Type:||Case study|
|Date:||Aug 1, 2018|
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