First branchial cleft anomaly extending to parapharyngeal space

Abstract

First branchial cleft anomalies are quite rare, and the majority of them are found in and around the ear canal, mostly superficial to the facial nerve. Very rarely, the anomalous tract of the first branchial cleft can go deeper to the facial nerve, necessitating a meticulous and extensive surgery. A 21-year-old student presented with slowly increasing cystic swelling in the infra-auricular region. Findings of the magnetic resonance imaging were consistent with the first branchial cleft cyst, which also exhibited a deeper extent of the lesion into the parapharyngeal space. The entire tract was excised along with the superficial parotidectomy by an open approach. In addition to illustrating the presentation and management of this peculiar case, the present report also reviews the latest literature around their management.

Background

Branchial cleft anomalies are rare causes of neck swelling. Their pathogenesis is still elusive, as none of the existing theories are able to explain their origin with evidential support.¹ According to the most accepted hypothesis, these anomalies result from failed obliteration of the branchial apparatus during embryogenesis.¹ The majority of the branchial cleft anomalies seen in clinical practice are due to the persistence of the second branchial apparatus, but rarely, they could arise from the defect in the first branchial cleft instead.^{1 2} Furthermore, among the first branchial cleft anomalies, the lesions extending medial to the facial nerve are quite rare and present a peculiar surgical challenge.³ Here, we report a rare type of first branchial cleft cyst that was extending deep to the facial nerve till the parapharyngeal space. There are only a few reports in the literature that describe the parapharyngeal extension of the first branchial cleft anomaly.^{4 5} Apart from providing detailed illustrations of the clinical, radiological and pathological features of the first branchial cleft cyst seen in the index case, we have discussed the management principles of such lesions and have summarised the recent literature in this regard.

Case presentation

A 21-year-old male patient presented to our department with a history of left-sided facial swelling for 1½ years. The swelling, localised at the left parotid region, had started spontaneously without any history of trauma and had progressed slowly over the months to the present size of a golf ball. It was painless and did not vary in size with chewing or swallowing. The patient had no problems related to the ear, nose or throat. He had normal developmental history and uneventful childhood. On examination, the swelling was located just underneath the left ear lobule, measuring 3×4 cm in its maximum dimension, without exhibiting any signs of local inflammation (figure 1). It was cystic, mobile and non-tender on palpation. The examination of the ear was unremarkable with a normal external auditory canal and tympanic membrane. Nose and throat were also normal on flexible endoscopy. The neck examination did not reveal any discharging sinus or scar, and the motor function of the facial nerve was normal on both sides. A magentic resonance imaging (MRI) was advised to know the nature and extent of the cystic lesion.

Figure 1.

Clinical picture showing the diffuse swelling underneath the left ear lobule.

Investigations

Contrast-enhanced MRI of the face showed a well-encapsulated cystic lesion in the left parotid space, going deep to the deep lode of the parotid, till the left parapharyngeal space (figure 2), and having superior extension upto the cartilaginous part of ear canal (figure 3). The lesion was hyperintense on both T1-weighted and T2-weighted images and was hypointense on T1 fat-suppressed sequence.

Figure 2.

MRI demonstrating the radiological characteristics of the first branchial cleft cyst in the left parotid space extending till the parapharyngeal space (star). The lesion was hyperintense in both T1-weighted (A) and T2-weighted images (B), hypointense in fat-suppressed T1 sequence (C) and exhibited no restriction in diffusion-weighted sequence (D).

Figure 3.

Coronal sections of MRI, (A) T2-weighted and (B) eSTIR_long TE CLEAR sequences, showing the cystic lesion in the parapharyngeal space and its superior extension till the cartilaginous portion of external auditory canal (star).

Differential diagnosis

Along with the young age of the patient, the slowly progressive cystic swelling in the parotid space, without pain or other signs of local inflammation led us to think of the first branchial cleft cyst. However, we did not find any sinus opening in and around the ear, prompting us to keep parotid cyst, sialocele or other cystic swellings of this region, or intraparotid lipoma as the possible differential diagnoses to the branchial cyst. Although in many such cases of non-specific cystic swellings of the parotid region, a fine needle aspiration cytology could provide the diagnostic clue, we did not have to do it in the index case as the radiological characteristics in MRI clearly suggested the diagnosis of first branchial cleft anomaly. Particularly, a well-encapsulated homogeneous cystic lesion, its extraglandular location, close proximity to the cartilaginous ear canal and typical hyperintensity in T2, all favoured the first branchial cleft cyst.

Treatment

Since the lesion was extending deep to the parotid gland and into the parapharyngeal space, the patient and his parents were explained in detail about the risk involved in the surgery, including that of possible facial nerve weakness. And, after obtaining a detailed informed written consent, the patient was taken up for excision of the cyst under general anaesthesia. During the procedure, after making the modified Blair’s incision, the entire tract of the branchial anomaly was exposed along with the surrounding parotid gland. The cyst had an abnormal cartilaginous lining adjacent to the cartilaginous part of the external auditory canal, but it did not open directly into the ear canal (figure 4). Nevertheless, after resecting a small cuff of ear canal cartilage at the attachment site of the cyst, the tract of the branchial anomaly was delineated medially, with the surrounding parotid tissue. Since the lesion was going deep to the parotid, a superficial parotidectomy had to be performed for achieving further exposure of the tract without risking the injury to the facial nerve. This was done by identifying the facial nerve at its exit point from the stylomastoid foramen and tracing all its distal branches until their emergence points out of the parotid gland (figure 4). Subsequently, the anomalous tract of the branchial cyst was identified going deep to the facial nerve trunk, till the parapharyngeal space (figure 4). By carrying out a meticulous dissection all around the lesion, the cyst and its entire tract (figure 5) were excised in toto along with the superficial parotidectomy specimen. After ensuring optimal haemostasis, a suction drain was placed, and the surgical wound was closed in layers.

Figure 4.

Intraoperative images showing, (A) the extent of the unobliterated portion of the first branchial cleft with cartilaginous lining (star) in close proximity to the parotid gland (triangle) and to the main trunk of facial nerve (black arrow), (B) its deeper extension medial to the facial nerve trunk till parapharyngeal space (star) after separation of the superficial lobe of the parotid gland (triangle), and (C) intact facial nerve trunk (black arrow) and its branches (white arrows) after excision of the entire tract with superficial parotidectomy.

Figure 5.

Gross picture of the excised branchial cleft cyst demonstrating the squamous-lined cavity with hair follicles (arrows) and attached cartilaginous remnants (star).

Outcome and follow-up

The patient had an uneventful postoperative recovery with normal facial nerve functioning and a well-healed surgical site. The pathological examination of the excised specimen showed squamous epithelium-lined cavity with hair follicles, sebaceous gland and mature cartilage (figure 6), confirming the diagnosis of the first branchial cleft anomaly. The patient is under regular follow-up, and at 5 months post surgery, he is symptom-free and doing well.

Figure 6.

Photomicrographs, H&E stained (40×), (A) demonstrating branchial cyst wall, lined by stratified squamous epithelium (white arrow), sebaceous glands (star) and mature cartilage (black arrow), and (B) denuded and fibrotic cyst wall lined (white arrow) by inflamed granulation tissue (black arrow).

Discussion

Based on the extent of the unobliterated portion of a branchial cleft, the anomalous tract could manifest itself as a cyst, sinus or fistula.^{1 2} Despite being congenital in origin, the first branchial cleft anomaly hardly manifests at birth. As in the index case, most of them become symptomatic during the later part of the first or second decades of life.^{2 6} Clinically, the majority of the first branchial cleft anomalies present as unilateral cystic swelling around the parotid region, with or without signs of recurrent infection, but, at times, there could be associated discharging sinus or fistula in and around the ear canal.^{1 2 6} If present, the opening of the first branchial sinus or fistula would be seen in the triangle between the external auditory meatus, hyoid bone and mentum of the mandible.⁷ Nevertheless, the typical location of the cystic swelling, along with the corroborating history, led us to suspect the first branchial cleft anomaly in the index case, which was further validated by MRI findings.

From the diagnosis point of view, although ultrasonography and computed tomography could aid in diagnosing the first branchial cleft anomaly with reasonable reliability, MRI is the most appropriate choice owing to its superior soft tissue delineation ability.⁸ In MRI, the characteristics of branchial cyst could vary depending on its fluid and protein content. Usually, they tend to be low-to-intermediate intensity on T1-weighted images and exhibit high intensity in T2-weighted images. In the index case, the lesion was hyperintense in both T1-weighted and T2-weighted sequences, but had low intensity in fat suppression sequence, suggesting protein-rich content. Also, there was no diffusion restriction in the first branchial cleft anomaly reflecting its non-proliferative nature. The MRI not only helps in differentiating the branchial cleft cyst from other cystic and solid lesions of the neck or parotid, but also demonstrates its surrounding extensions, enabling an appropriate planning of surgical approach.

By reviewing the internal morphology of anomalous tracts in six cases of first branchial cleft anomalies, Work in 1972 classified these lesions into two distinct types, a classification scheme that has been validated by subsequent studies for its clinical relevance.³ The case described in this report had a type II first branchial cleft anomaly, which is much rarer than a type I anomaly.¹ Irrespective of whether it is type I or II, the treatment of choice for the first branchial cleft anomaly is to surgically excise it; however, the extent of the surgery may vary between them.¹ The primary objective of surgical intervention is to remove the entire tract without leaving behind any remnants and to do so without harming the facial nerve function; and to achieve this objective, unlike the type I first branchial cleft anomalies, most of the type II anomalies necessitate an extensive surgery like a superficial parotidectomy.^{1 6 9} In some of these cases, superficial parotidectomy can be avoided, particularly, if the lesion is not involving parotid tissue and is not going close to the facial nerve. In fact, whenever feasible, attempt should be made to preserve the part of the superficial lobe of the parotid gland that is located away from the anomalous tract even in type II lesions. The case presented here was not only going medial to the facial nerve, but had an unusual deeper extension into parapharyngeal space, which has been reported sparsely in the literature.^{4 5} Interestingly, previous studies have employed combined approach excision for deeper cysts, particularly for those with the significant pharyngeal component.^{4 5} Contrarily, the present report highlights that the transcervical excision can be safe and effective even in large lesions with parapharyngeal extension. Nevertheless, in large first branchial cleft anomalies with deeper extension, the intraoperative use of a facial nerve monitor could assist the surgeon in maintaining the intactness of the nerve throughout the transcervical procedure and can be taken advantage of, if available.⁶

Finally, a few of the recent reports have revisited the alternate therapeutic options like repeated needle decompression with or without injection of sclerosant agents for treating the cystic lesions of the neck, including a few second branchial cleft cysts.^{10 11} However, since the safety profile of injection sclerotherapy in first branchial cleft anomalies that extend close to the facial nerve is still questionable. Also, considering the lack of clarity about the malignant potential of a sclerosed branchial cyst, the surgical excision of the entire tract seems to be a safer bet than offering the sclerotherapy for first branchial cleft cysts.

Patient’s perspective.

I was concerned about the asymmetry of my face due to the swelling below my left ear. After consulting the doctor, I was a bit worried about the surgical morbidity, but fortunately, the procedure was successful without any postoperative problems. I was having intermittent throat pain on the left side at times, which has also subsided after the surgery.

Learning points.

• Though first branchial cleft anomalies are rare, they should be considered in young patients in their first or second decades of life who present with a typical cystic swelling.

• The absence of sinus opening in and around the ear canal does not rule out the first branchial cleft anomaly.

• MRI should be the investigation of choice, particularly in large type II lesions with deeper extension.

• Most of the type II first branchial cleft anomaly may necessitate superficial parotidectomy for complete removal with preservation of the facial nerve.

Ethics statements

Patient consent for publication

Obtained.