First Branchial Cleft Anomaly Mimicking Cholesteatoma: A Pediatric Case Study and Surgical Approach

Introduction

Branchial cleft anomalies are common congenital diseases that occur when a part of the branchial cleft fails to involute, and the entrapped remnant forms an epithelium-lined cyst with or without a sinus tract to the overlying skin. The majority of these anomalies involve the second branchial arch [1]. First branchial cleft anomalies (FBCAs) are rare congenital disorders with an incidence of approximately 1/100 000, accounting for 8–10% of all branchial cleft anomalies. Among these, 68% are cysts, 16% are sinuses, and 16% are fistulas [2,3]. As early as 1972, Work proposed dividing the FBCAs into type I and type II. Type I anomalies are generally cysts of ectodermal origin and are considered to be duplications of the membranous external auditory canal; these cysts are commonly located near the ear and extend to the postauricular crease, running superior to the facial nerve. Type II anomalies are cysts, sinuses, or fistulas of ectodermal and mesodermal origin, which are considered to be duplications of the membranous external auditory canal and pinna, containing adnexal skin structures or cartilage that may extend to the face, upper neck, or external auditory canal and often lie medial to the facial nerve [4].

The opening of the sinus/fistula can occur anywhere on the lateral neck anterior to the sternocleidomastoid muscle, below the external auditory canal, posterior to the submandibular angle, and above the hyoid bone [5]. The typical clinical manifestation of FBCAs is swelling in the parotid or postauricular area, which can cause pain or purulency due to infection and inflammation. The external auditory canal may also have a purulent discharge [2]. However, due to anatomical diversity, the clinical manifestations of FBCAs are variable and complex, giving rise to broad possibilities for differential diagnosis of FBCA, including preauricular sinus, lymphadenitis, lymphatic malformation, parotid mass, and abscess of skin adnexa [1]. Therefore, FBCAs are often misdiagnosed and inappropriately treated if the doctor is inexperienced, and diagnosis can be challenging [2].

The purpose of this report was to share the diagnosis and treatment of an extremely rare case of a 4-year-old girl with an FBCA presenting as a painless mass of the left external auditory canal and an inconspicuous depression in the left mandibular angle, a presentation that could easily be misdiagnosed as “cholesteatoma of the middle ear”.

Case Report

A 4-year-old girl without any symptoms of ear discomfort presented to our department due to “finding a mass in the left ear canal more than 2 months ago”. Otoscopy revealed local uplift of the posterior wall of the middle part of the left external auditory canal, no secretions, and no tympanic membrane (Figure 1A). Hearing examination revealed no loss of hearing in either ear. Computed tomography (CT) of the temporal bone revealed a soft-tissue density shadow in the left external auditory canal and middle ear cavity (Figure 1B). Therefore, the outpatient doctor considered the diagnosis of middle ear cholesteatoma and decided to hospitalize the child to prepare for further treatment.

After hospitalization, the attending doctor believed that there were several contradictions between the preliminary examination results and the diagnosis of “middle ear cholesteatoma”: First, the CT image revealed a suspected mass in the middle ear but no loss of hearing. Second, the CT image revealed a soft-tissue density shadow in the middle ear and external ear canal but no obvious destruction of the surrounding bone. After careful physical examination, we found an inconspicuous depression in the left cheek near the mandibular angle (Figure 2). Moreover, the B-ultrasound image showed a fistula and a cystic mass at the junction with the external auditory canal (Figure 1C). Inner ear magnetic resonance imaging (MRI) revealed a sharply demarcated fistula in the parotid gland opening into the cheek area from the external auditory canal (Figure 1D). In summary, all imaging and physical examinations supported the diagnosis of FBCA. Surgical excision was performed as soon as possible before infection.

Surgical excision was performed under general anesthesia, and the facial nerve was monitored. Intraoperative findings revealed that the facial nerve straddled the fistula surface and that the fistula extended from the bottom oblique to the inferior wall of the external auditory canal (Figure 3). The fistula tissues were carefully dissected from the facial nerve and surrounding structures. After incising and separating part of the external ear canal cartilage, the fistula and sac found in the inferior wall of the external ear canal were completely removed. After the preauricular incision was sutured, otoscopy revealed local skin damage near the tympanic membrane on the back wall of the left external auditory canal and a duplicate external auditory canal (Figure 4A). Finally, canalplasty was performed. The postoperative diagnosis was “first branchial cleft fistula (Work type II)”.

The pathological examination showed “lumen is seen between the muscle tissues, lined with squamous epithelium and surrounded by inflammatory cell infiltration”, which confirmed that the pathology sample from the operation was consistent with branchial fistula. During the 8-month follow-up period, there was no facial nerve palsy or signs of clinical recurrence (Figure 4B). At the end of the 8-month follow-up period, the surgical scar had healed, and there was no constriction of the left ear canal.

Discussion

FBCAs present as cysts, sinuses, or fistulae in the lateral neck between the sternocleidomastoid muscle and mandibular angle, below the external auditory canal, and/or above the hyoid bone. Failure of embryological tract closure or duplication of the embryological tract is the likely etiology of FBCAs [2]. The timing of cleft closure coincides throughout embryonic development, with the appearance of the developing parotid gland arising from the second branchial arch and the migration of the facial nerve; therefore, the relationship of FBCAs with the external auditory canal and facial nerve of the parotid region will usually be intimate [2]. The tract can pass deep or superficially to the facial nerve, or between the branches of the facial nerve, and then protrude into the cartilage of the external acoustic meatus [5]. Surgical management of FBCAs can result in multiple complications including permanent or temporary facial nerve palsy, the incidence of which can be as high as 21 to 41% [5]. Therefore, during surgery in this case, we attached great importance to the protection of the facial nerve, and used facial nerve monitoring throughout the operation. Intraoperative findings revealed that the facial nerve straddles the fistula surface, which is anatomically consistent with Work type II.

The tympanic membrane is considered a fusion point for the 3 primary vestigial layers of the first branchial apparatus, so abnormal embryologic development in this region often leads to congenital otologic abnormalities [6]. Justin R. Shinn et al reviewed several cases in which children with FBCAs most commonly presented with a variety of otologic complaints (40.7%), ranging from external auditory canal cysts to cholesteatomas. Even if not the main complaint, the occurrence of otitis media was found in previous medical records [7]. Anatomic malformations of the external auditory canal were observed in more than 50% of patients. In the present case, the mother of the child saw the external ear canal mass despite no report of otologic symptoms; under these circumstances, diagnosing FBCAs is rather difficult because such anomalies are quite rare. Misdiagnosis and inadequate treatment of FBCAs may lead to recurrent infection, cicatricial contracture due to multiple incision drainage procedures, and facial nerve injury [7]. When a mass was found in the external auditory canal, careful otologic evaluation with otologic endoscopy, CT, or MRI helps clinicians correctly diagnose FBCAs. MRI is especially helpful for preoperative evaluation of the relationship between the facial nerve and tract [7]. Focused ultrasound is also a useful tool for quick diagnosis. The sonographic features of FBCAs include a smooth outline and uniform anechoic nature with posterior enhancement [8]. Incomplete removal of the internal fistula is the primary cause for the high recurrence rate associated with first branchial fistula resection. Many studies have confirmed that FBCAs are closely related to the external auditory canal. Therefore, it is very important to carefully examine the external auditory canal for abnormalities before surgery [6]. If preoperative examination reveals a connection between the superficial skin and tympanic membrane or external auditory canal, concurrent tympanoplasty or canalplasty should be performed. The facial nerve should be monitored in all cases to avoid facial nerve injury [7].

Conclusions

Because of their rarity, FBCAs are often misdiagnosed and inappropriately treated. This report has highlighted the importance of the correct diagnosis and treatment of FBCAs and awareness of anatomical associations and complications. Careful and comprehensive otologic evaluation can help clinicians make a correct diagnosis. If preoperative examination reveals a connection between the superficial skin and external auditory canal, concurrent canalplasty should be performed.