A Rare Case of Parotid Swelling Presenting as Branchial Cleft Cyst

Abstract

First brachial cleft cyst arise due to incomplete fusion of first and second brachial arches. It is classified into type 1, which is thought to arise from the duplication of the membranous external ear canal and are composed of ectoderm only, and type 2 that have both ectoderm and mesoderm which presents as parotid swelling. As it is rare it is easily misdiagnosed and mismanaged. First branchial cleft cyst are rare causes of parotid swellings as in this case reports.

Introduction

Branchial cleft cysts are also called as lymphoepithelial cysts. The definition and origin of a branchial cyst remains as such a controversy [1, 2]. It has been postulated that the cyst represents the remains of pharyngeal pouches or clefts. [3, 4]. They appears at some uncommon anatomical sites like in the oral cavity, Major salivary glands, cervical lymph nodes, tonsils, thyroid gland, juxtabronchial and pancreas [5, 6]. They are often multicentric and may be unilateral or bilateral [7, 8].

First branchial cleft cyst are extremely rare cause of parotid swellings and is comprised of less than 1% of all branchial anomalies [9]. We present one of such rare case of parotid swelling.

Case Report

A 27 year old female patient presented to OPD with a history of swelling in left parotid region since childhood which was small to start with, but over the last 5 years the growth has progressed gradually to the present size. The swelling was solitary, painless. Upon local examination the swelling was of approximately 2*2 cm, well defined, nontender located at the angle of mandible in the left preauricular region over the parotid gland. There was a punctum of approximately 0.5cm on the surface of swelling. There was no history of discharge through the punctum. Skin over the punctum was loose and not adherent. The overlying skin was normal in color and freely mobile over the swelling. Facial nerve examination was within normal limit. Intraoral examination revealed normal salivary flow (Fig. 1).

Fig. 1.

Shows left infraauricular swelling involving left parotid gland with a punctum on its surface

Investigations

1. Elisa – (HIV) was nonreactive

2. Ultrasonography of Left Parotid Region revealed a welldefined intraparotid, round to oval cystic lesion in superficial lobe of parotid gland (Fig. 2).

3. Computerised Tomography of left parotid region with contrast enhancement was suggestive of a welldefined peripheral enhancing cystic lesion with discrete fat globules in left parotid region of aprox 29*27*30 mm which was suggesting of dermoid cyst (Fig. 3).

4. Fine Needle Aspiration Cytology revealed inflammatory cells comprising of macrophages, lymphocytes, neutrophils against necrotic background along with hyaline material.

Fig. 2.

Ultrasonography of left parotid gland showing round to oval cystic lesion in superficial lobe

Fig. 3.

Computerised tomography scan of left parotid region with contrast showing enhancing cystic lesion with fat globules in superficial lobe of parotid

Therefore on Basis of History, Clinical Examination and Investigations, Provisional Diagnosis of A benign Parotid Cyst was Made

Differential diagnosis for the above being sebaceous cyst, dermoid cyst, kaposis sarcoma (ruled out as HIV was nonreactive).

We then took the patient for Superficial parotidectomy under general anaesthesia.

Modified Blairs (lazy s shaped) parotid incision was taken. Intraoperatively there was a well-defined cystic lesion. Intraoperatively there was an accidental puncture of the cyst which revealed yellowish cheesy material inside. The cyst tract was attached to the inferior surface of tragal cartilage and ear cartilage. Another sinus tract through the punctum was blind of approx. 1cm. The cyst was infiltrating superficial lobe of parotid gland. Facial nerve was identified and traced all along its course. It was found inferior to the posterior belly of digastric. Facial nerve was abnormally tortuous. Superficial parotidectomy was performed with excision of the cartilage of the ear attached to the cyst and sent for histopathology examination. Facial nerve was preserved (Figs. 4, 5, 6, 7, 8).

Fig. 4.

Cyst sac is seen with cheesy pultaceous material within the sac in superficial lobe of parotid. The cyst is attached to the ear cartilage

Fig. 5.

The pointed arrow shows the facial nerve situated beneath the superficial lobe of parotid and the cyst

Fig. 6.

Facial nerve is seen lying over deep lobe of parotid post excision of superficial lobe of parotid along with cyst

Fig. 7.

Facial nerve with its abnormally tortuous course is preserved with all its branches intact

Fig. 8.

Postoperative image of the patient

Follow-up: Patient Recovered Fully with No Evidence of Facial Nerve Palsy (Fig. 9).

Fig. 9.

Shows patient on postoperative day 15 with well healed wound and facial nerve examination within normal limits

Histopathology report: (1) The cheesy material revealed amorphous granular material and leucocytes (Fig. 10). (2) Section of cyst shows lobules of salivary tissue with hyaline cartilage bars. Cyst with cuboidal epithelium lining was most likely suggestive of branchial cleft cyst (Fig. 11a, b).

Fig. 10.

Histopathology specimen shows amorphous material admixed with polymorphs (pink) within the salivay gland tissue (blue)

Fig. 11.

In this histopathology slide fibrocollagenous cyst wall is seen lined by cuboidal epithelium

Discussion

Hunczowski described the first branchial cyst in 1789 [10]. Lagenbeck reported the first surgical treatment of a branchial cyst in 1859 [11]. They are usually misdiagnosed due to their rarity.

Anomalies of the first branchial cleft are rare, accounting for less than 8% of all branchial anomalies  [12, 13], with an annual incidence of ∼1/1 000 000  [14] and are more common in the female population compared with the male population  [15].

Branchial cleft anomalies result due to incomplete closure or obliteration of the cervical sinus of “His” during 6th and 7th week of embryogenesis. They can be cyst, sinuses or fistulae. Specifically, the lack of degeneration of the cervical sinus created by the growth of the second arch over the third and fourth arches is the proposed cause. These anomalies represent fusional lesions [9].

The location of the branchial cleft cyst is determined by which branchial cleft failed to obliterate, second cleft cyst being more common. The clinical presentation of a first branchial cleft cyst includes swelling in the preauricular region (24%), parotid (35%) or cervical region (41%) [16].

Broadly First cleft anomalies are classified as type I or type II lesions [17, 18]. Type I lesions are duplications of the membranous external auditory canal and contain ectodermal elements only. Type II lesions are composed of ectoderm and mesoderm and therefore may contain cartilage.

Type I lesions course lateral to the facial nerve, whereas type II lesions pass medial to the nerve and may present as preauricular, infraauricular, or postauricular swellings or cysts inferior to the angle of the mandible [16].

There were many studies regarding the classification of branchial cleft cysts:

Arnot, in 1971, classified branchial cleft cyst into two anatomical types: type1 presenting with a defect in the parotid region in early to mid adulthood and type 2 presenting in childhood with defect in the anterior triangle of neck and a tract communicating with external auditory meatus. Type1 defects is the result of burial of cell rests during the closure of the ventral portion of the first cleft. Type 2 defects are due to incomplete obliteration of the cleft [17].

Work in 1972 described two similar classification on the basis of histology and embryology. Type 1 defects are cystic and of ectodermal in origin and lined by stratified squamous epithelium. They are generally anteroinferior to the ear lobe in association with the parotid gland and superficial to facial nerve. Type2 are of both ectodermal and mesodermal in origin [18].

Finally, Olsen in 1980 ¹⁹ proposed a simpler classification system based on the clinical presentation of the lesion:

• Cyst.

• Sinus.

• Fistula.

The first branchial cyst of parotid gland was described by Hildebrandt in 1895 [20].

First branchial cleft cysts are an extremely rare cause of parotid swellings and comprise less than 1% of all branchial anomalies [9].

The first branchial apparatus gives rise to specific adult anatomical structures. It develops into the maxilla, mandible, eustachian tube, external auditory canal, and portions of the middle ear structures. This developmental process is completed by 6–7 weeks. From 6 to 8 weeks, the parotid gland forms from endoderm within the mouth and branches posteriorly toward the ear. At the same time, the facial nerve and muscle migrate anteriorly. Because the parotid gland and facial nerve have a somewhat later embryologic development, a vestigial first branchial anomaly can insinuate itself in a variable relation to the parotid gland or facial nerve [21].

In 1959, Bhaskar and Bernier examined 468 specimens submitted as branchial cleft cysts and interpreted 96 percent of them to be cystic changes in regional lymph nodes. The cystic change was caused by epithelial entrapment within the node at the time of development. In addition, these authors noted that the parotid gland develops at the same time as the regional lymph nodes and speculated that this was the origin of the entrapped epithelium [22].

The first branchial cleft cyst is in close association with the parotid gland. The sinus opening is usually in the Pochet’s triangle which is bounded by the EAC above, the mental region anteriorly and hyoid bone inferiorly [23, 24]

Branchial cyst in parotid gland are more common in third decade of life with a mean of 44 years [25]. Branchial cleft cyst occur within the lymph nodes of parotid gland or on the surface of the gland [7]. The cyst is mostly painless, slow growing, firm, elastic and fluctuant mass and vary from 0.5 to 5 cm in diameter [26]. The superficial lobe of parotid gland is involved in most of the cases [27].

Investigations

A number of preoperative investigations may be useful in establishing the diagnosis. CT scan is useful differentiating solid from cystic lesions of the parotid gland although it sometimes carries a risk of false positive results [28]. CT may be particularly useful not only to visualize the full extent of the lesion, but also to delineate its association with adjacent structures. An ultrasound scan has also been proved to be a rapid, inexpensive and readily available tool in differentiating solid from cystic lesions [29, 30]. Fine needle aspiration has also been useful in some cases.

Management

The management of first branchial cleft cyst is complete surgical excision with preservation of facial nerve and to reconstruct the otological structures if necessary [32, 33].

One should also be prepared to remove parts of noncritical structures intimately related to the cyst or its tract, such as a section of the cartilaginous EAC or the posterior mandible.

The reported recurrence rate can be as high as 14–22% after surgical excision when there is a history of prior infection or incomplete excision [33, 34].

Conclusion

The branchial cleft cyst, or cervical lymphoepithelial cyst, is a pathological entity whose etiology has yet to be delineated. It shares a clinical presentation with other pathological entities of the neck, making diagnosis difficult at times. Therefore one should always keep in mind and rule out all the differential diagnosis in cases of swellings of parotid glands or cervical swellings etc. Surgical excision of these lesions is considered curative, with recurrence unlikely if all remnants are removed.