NA Aziz, FA Rahim, KB Noh, H Mohamad

Abstract

Branchial anomalies are the second most common head and neck lesions in children, following thyroglossal duct cysts. They typically manifest as lateral neck masses with potential infection, intermittently draining sinus, or fistula. Identifying the tract of a branchial fistula presents a challenge to surgeons. Preoperative imaging, such as computed tomography of the neck with fistulogram, and direct laryngoscope procedures are immensely helpful in locating the fistula. However, difficulties arise when the tract's location deviates from the standard anatomical development, as encountered in this case. Internal openings of branchial fistula are commonly found in the ear canal, tonsillar fossa, or pyriform fossa. We present a rare case of a branchial sinus with internal opening over the base of tongue that later develop into a pseudofistula, which, to the best of our knowledge, has not been reported in the existing literature.

Introduction

Branchial cleft anomalies rank as the second most common congenital head and neck lesions in children, comprising about 30% of congenital neck diseases.¹ Although they present at birth, diagnosis may occur later in life.

These anomalies result from developmental disruptions of the branchial apparatus during the third and seventh weeks of gestation. Normally, the clefts of the branchial apparatus undergo obliteration as various structures evolve. However, when this obliteration fails, it can lead to the formation of branchial cleft cyst, sinuses, or fistulas.

Branchial fistulas are relatively uncommon, compared to cysts and sinuses.^2,3 This article reported a unique case of a branchial sinus with an unusual internal opening that later develop into pseudofistula, which has not been previously reported.

Case Report

One-year-old boy presented with a swelling over the left submandibular region since birth. There was one episode of infection where the swelling formed an abscess and spontaneously ruptured forming an external opening over the upper third of the neck, anterior to the sternocleidomastoid muscle. The infection responded well to antibiotic however the swelling and external skin opening persist with recurrent discharge.

Upon examination, a swelling measuring approximately 2 cm x 3 cm with an external opening seen over the left lateral upper neck. The rest of ear, nose and throat examinations including flexible nasopharyngolaryngoscopy showed normal finding. Neck ultrasound (USG) revealed a well-defined unilocular cystic lesion over the submandibular region, located anterior to the left sternocleidomastoid muscle and carotid vessels.

A computed tomography (CT) scan of the neck with fistulogram demonstrated an uniloculated hypodense lesion with enhancing wall, seen over the left submandibular region, anterior to left sternocleidomastoid muscle measuring 1.5 cm x 1.7 cm x 1.4 cm. The left submandibular gland is not well visualised. The lesion has an external opening over the skin and a blind-ended tract connecting to the sublingual region (Figure 1). It also has close proximity with the left external carotid artery posteriorly.

Figure 1 Coronal cut of CT neck and fistulogram shows the lesion having a blind-ended tract over the sublingual region (arrow).

Patient underwent examination under anaesthesia and instillation of methylene blue through the external opening was performed as a method to identify the possible internal opening. During procedure, a gushed of blue dye was noted coming out from an internal opening over the left lateral side of circumvallate papillae of the tongue (Figure 2). The internal opening was further identified with a small catheter cannulation and then cauterised using monopolar diathermy. Alas, despite cauterisation of the internal opening the child still experienced clear discharge from the external punctum during follow-up, prompting the planning of surgical excision of the fistulous tract.

Figure 2 (a) Shows methylene blue stained left base of tongue, originating from the internal opening over the circumvallate papillae (arrow). (b) Shows internal opening of branchial cleft fistula cannulated with suction tube 3 mm.

Discussion

Congenital neck masses in children can lead to a variety of diagnoses such as thyroglossal duct cyst (70%), branchial anomalies (30%), lymphangiomas, vascular malformations, dermoid cysts or even teratoid cysts.¹ Branchial anomalies are the second most common congenital head and neck lesions in children.^1,4 Although numerous theories are associated with their development, the prevailing view is that they result from a defective closure of arches and clefts during embryogenesis.^2,3 Other theories include pre-cervical sinus, thymopharyngeal ductal origin, and cystic lymph node origin. They can be diagnosed at any age but are mostly found in children from birth and may present as a sinus, fistula, or cyst. Typically, they appear unilaterally, but bilateral cases have been reported and are frequently familial.⁴ Patients usually presented with lateral neck swelling associated with intermittent mucopurulent discharge from the neck.

If structures of the branchial apparatus are unable to resolve and merge, they can result in the formation of a fistula, which is a connection between the skin and mucosa, a sinus tract, which is a connection with the skin, or a cyst, which does not have a connection with either the skin or mucosa.⁴ Fistula is defined by a communication between two epithelised surfaces. A congenital branchial fistula would require a connection between a persistent pouch and a cleft. A pseudo-fistula may form between a pouch internally and an external opening produced secondary to an infection or iatrogenic.^2,5 To be a congenital fistula, an external opening would need to be present at birth. True congenital branchial fistula does occur but is rare and most reported fistulae are either wrongly named or acquired in nature.⁵

Most branchial anomalies arise from the second pharyngeal arch, accounting for approximately 90% of cases, while anomalies from the first arch represent about 8%. Anomalies associated with the third and fourth arches are exceedingly rare.⁴ According to Bailey's classification, second branchial cyst can be divided into four subtypes based on their location in relation to the neck structures. Second branchial fistulas usually have an external opening on the lower neck, anterior to the sternocleidomastoid, and they extend proximally and medially between the internal and external carotid arteries and may communicate with the pharynx through the palatine tonsil.

Second branchial arch anomalies typically opened into the tonsillar fossa, whereas third and fourth branchial arch anomalies opened into the pyriform fossa. Based on its location and the course of its tract, this patient presented with possibly a second branchial sinus, with an internal opening which later develop into a pseudofistula following an episode of infection. However, the internal opening which is located at the circumvallate papilla of the tongue, not only defies the standard anatomical development theories of branchial anomalies, but it also poses a challenge for surgeons to identify the opening. Across literature, there is no other case that reported such case of branchial pseudofistula with an unfamiliar inner opening.

In our case, the presence of an uncommon internal opening located over the circumvallate papilla of the tongue surface raises the possibility of a congenital thyroglossal duct cyst. Thyroglossal duct cysts are atypical remnants of thyroid gland that usually present as cyst, although some literature reports cases of thyroglossal duct sinus and fistula.⁶ Due to the embryological development of the thyroid gland, thyroglossal duct cyst usually occur along the midline of the neck anywhere along the thyroid migration route which extends from the base of tongue to the thyroid gland. Our case however showed the cyst to be situated laterally over the left side of the neck, contrary to the midline swelling usually seen in thyroglossal duct cyst. The internal opening was also located on the left side of the base of tongue, contradicting the site of the thyroglossal duct anomalies, which is at the foramen caecum. Apart from that, the external opening was located laterally, anterior to the sternocleidomastoid muscle, a common site for brachial cleft anomalies. These clinical findings rule out the possibility of a thyroglossal duct anomaly in our case.

The role of imaging is crucial in preoperative planning to delineated fistulous tract and identifies its relations to other important structure. The choice of common imaging modalities, ultrasound, barium swallow, CT fistulogram and magnetic resolution imaging (MRI) are frequently chosen for preoperative planning and excision of branchial cleft fistulas. USG is an effective initial imaging modality for evaluating neck masses in children. It is also used in centers where CT scanning and MRI are unavailable. Although ultrasound can confirm the cystic nature of the mass, it does not adequately evaluate the extend and depth of neck lesion and delineate its fistula tract.

Barium study is useful to identify fistulous tract if it is done about four to six weeks following an acute inflammatory phase. Despite that, drinking barium in an attempt to delineate the sinus tract may be falsely negative because the sinus opening may be occluded by oedema in acute phase.⁷ Conventional CT scan with intravenous contrast is also one of the modalities of choice in cases of branchial fistula. It is useful to rule out other cause of neck swelling. In comparison to MRI, CT is better in detection of gas in sinus tract. Few authors reported the usefulness of air CT where air was used as a contrast agent by drinking carbonated water instead of barium using modified Valsalva and trumpet manoeuvres.^8,9

CT fistulogram is a relatively new method and has been considered to be better than conventional CT in delineating the often-tortuous fistula course. However, cannulating the external opening during the procedure may require high cooperation from the patient. Apart from that, cannulation may cause scarring, inflammation, and infection that can yield a negative result. MRI is a helpful modality of choice and is preferable at certain centres as it provides superior soft tissue planes while minimising exposure to ionising radiation for children. MRI also provides the best soft tissue contrast and soft tissue delineation between the sinus, fistula, or cyst and the surrounding important structure of the neck which is essential in preoperative planning to avoid debilitating intra operative complication. However, MRI was not performed in our case in view of limited resources and long waiting list.

Treatment modalities for branchial cleft fistula include antibiotics with surgical incision and drainage in cases of infection, surgical tract excision as well as closure of the tract opening. Endoscopic branchial fistula closure using various techniques such as plasma ablation, laser cauterisation, electrocautery, chemical cauterisation, and internal orifice suturing have been reported.¹⁰ The aim is to seal the inner opening in order to prevent the entry of food residues, oropharyngeal secretions, bacteria, and viruses from the upper aerodigestive tract, thus preventing the occurrence of fistula infection. Endoscopic surgery, which is minimally invasive, cost-effectiveness, with a brief hospital stay, makes it an ideal choice of treatment. However, failure of endoscopic obliteration of the inner opening, as seen in this case may warrant surgical excision to prevent further recurrence and infection. In order to prevent recurrence, it is necessary to thoroughly trace the tract up to the internal opening and excise, ligate or seal it. Complete resection requires the detection of the tract up to the internal opening, and trials of a variety of techniques reported, including the insertion of catheter tubes and the injection of dyes, have been carried out in this regard. Externally, it is advised to do a complete surgical excision using a step ladder technique, involving two independent horizontal incisions. This approach provides excellent visibility of the fistulous tract while minimising the need for extensive tissue dissection.⁴

Conclusion

In conclusion, we presented a rare case of a branchial cleft sinus with an unusual internal opening at the base of the tongue that later develop into a pseudofitula. This atypical presentation challenges the conventional anatomical development theories of branchial anomalies and poses a significant challenge for surgeons in identifying the opening. Timely and accurate imaging, along with minimally invasive cauterisation, are crucial in managing such cases. Despite the rarity of our case, it highlights the importance of thorough examination and the potential for encountering uncommon presentations of branchial anomalies. Further research and reporting of such cases are necessary to expand our understanding and improve clinical management.

Conflict of Interest

All authors have disclosed no conflicts of interest.

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