An Uncommon Salivary Gland Swelling- Parotid Duct Cyst and Its Management

Abstract

Cysts in the parotid region are more common in the gland than in the duct. Isolated cyst of parotid duct is a rare presentation. The treatment for most of the cystic lesions of the parotid or the parotid duct is the excision of the cyst with superficial parotidectomy. However, these lesions can be approached intra-orally for marsupialization achieving the same surgical results with less morbidity. This paper presents a rare case of parotid duct cyst which was managed by intraoral drainage and marsupialization. A 53-year-old female presented with swelling in the right cheek, associated with frequent fluid drainage inside the oral cavity for four months. Radiology and Fine needle aspiration revealed a benign parotid duct cyst with normal parotid gland. It was managed by a simple surgical technique of marsupialization. The patient was followed up for 1 year with no evidence of recurrence. Marsupialization obviates the need for parotidectomy in the simple cystic lesion of the parotid duct, unlike the cystic lesion in the gland per se and also reduces risk of recurrence. The simplicity and lack of major complications make it an effective treatment for salivary duct cysts.

Introduction

Salivary duct cysts (SDC) are more common in the ducts of major salivary glands and rarely occur in the minor salivary glands. These are true cysts that have a congenital or acquired origin. The most common is acquired type, following obstruction of the duct. Cysts in the parotid region are more common in the gland than in the duct. Radiological imaging plays a vital role in differentiating these lesions. Fine needle aspiration biopsy helps in the diagnosis and to differentiate benign from malignant cysts. In the existing literature, the treatment for most cystic lesions of the parotid or the parotid duct is the excision of the cyst with superficial parotidectomy. We present a 53-year-old female with a parotid duct cyst managed by intraoral drainage and marsupialisation under local anaesthesia. The patient was followed up postoperatively for 1 year, and no recurrence was detected. This clinical record describes a rare pathology and its management.

Case Presentation

A 53-year-old female presented with swelling in the right cheek for the last four months, which gradually increased in size. The swelling was associated with pain and increased size while eating, followed by intermittent fluid drainage inside the oral cavity. There was no history of fever, pus discharge from the swelling. There was a history of recurrent episodes of pain in the right cheek in the past for which she got an ultrasound revealing a 4 mm calculi at the terminal end of the right parotid duct, which was treated conservatively with massaging and sialogogues. No history of diabetes mellitus or autoimmune disorder.

On examination, there was diffuse, soft 3 * 3 cm swelling over the right cheek at the level of ramus of the mandible. On intraoral palpation, there was a single, well-defined, localized swelling that was approximately 2* 2 cm which was smooth, fluctuant and uniformly cystic in consistency producing a bulge in the right buccal mucosa around the parotid duct orifice. On bimanual palpation, the parotid gland was palpable separate from the cystic lesion. No warmth or tenderness was appreciated. On compressing the swelling, clear serous fluid drained into the oral cavity via the papilla of the parotid duct along with a decrease in size of the swelling.

An ultrasound scan revealed a single, 2.5 cm x 2.5 cm well-defined anechoic area in front of the right parotid gland sparing the parenchyma of the gland. There was no evidence of calculi. There was no internal blood flow with colour Doppler. On contrast-enhanced CT, a well-defined fluid attenuating hypodense lesion measuring 3 × 2.9 × 2.8 cm was noted in the right cheek. No solid component was noted within the hypodense lesion. No calculi were noted. The lesion was abutting the lateral wall of the maxilla superomedially without bony erosion. The right parotid gland was normal and away from the cystic lesion. No significant cervical nodes were noted. The submandibular gland and the other side parotid gland were normal (Fig. 1A and B). Fine need aspiration from the right cheek swelling yielded clear serous discharge. On microscopy, it was sparsely cellular, showed some epithelial components without lymphoid tissue in a proteinaceous background. No atypical cells were seen, suggestive of a simple cyst.

Fig. 1.

Radiological Images

A- Contrast CT Coronal view showing well defined hypodense lesion in right cheek abutting buccal mucosa bounded supero-medially by maxilla(White arrow). B- Axial view of same CT scan showing the hypodense cystic lesion in right side at the level masseter separate from the right parotid gland(White arrow)

The patient was planned for a right parotid duct cyst exploration and Marsupialization under local anaesthesia. Using a 0-degree endoscope via the oral cavity, the cyst and the duct opening was visualised, and around 10ml of clear serous fluid was expressed on applying pressure over the cyst. Using pencil tip cautery, a circular incision was made over mucosa overlying the medial wall of the cyst, and overlying mucosa was removed. The medial wall of the cyst was visualized (Fig. 2A). A linear incision was given over the medial wall till the lower extent of the cyst cavity. The cyst wall was sutured to the adjacent mucosa using 3 − 0 vicryl to marsupialize the cyst cavity into the oral cavity (Fig. 2B). The cyst wall was sent for histo-pathology which showed cyst with mucinous secretion with cuboidal to columnar lining epithelium suggestive of salivary duct cyst (Fig. 3A and B). Post-surgery the patient was discharged on the same day. She was allowed to take a semi-solid diet from the 2nd postoperative day after ensuring wound healing at the operated side.

Fig. 2.

Intra and Post-Operative Images. A- Endoscopic picture of the parotid duct cyst after removal of overlying mucosa showing the cyst wall(Blue arrow). B- Marsupialized cyst after removal of part of the cyst wall. C- Post operative picture showing healed cavity(Black arrow)

Fig. 3.

Histopathological images of the Cyst wall. A- 4x. B- 40x– H&E sections show cyst with mucinous secretion lined by cuboidal to columnar lining epithelium

The postoperative period was uneventful. The patient was followed up for 1 year and no recurrence was detected. The patient was initially complaining of food particles getting stuck in the maruspialized cavity, which was no longer present after the complete wound healing (Fig. 2C).

Discussion

Cystic lesion of the parotid gland is a rare entity and account for 2–5% of primary parotid lesions [1]. Salivary duct cysts ( SDC), also known as sialocysts or simple cysts, are rarer than parotid gland cysts. It occurs with wide age distribution, with most patients above 30 years of age without sex predilection. These are mostly retention cysts that have a congenital or acquired origin. The most common is acquired type following obstruction of the duct that leads to the formation of these cysts [2]. About 80% of the cystic lesions of salivary glands are seen in the parotid gland. This may be due to various causes, like calculi, mucous plugs, postoperative and post-inflammatory stricture. They can present as swelling in the cheek with an intermittent increase in size and pain while eating. In our case, the patient presented with similar complaints, along with drainage of clear fluid into the oral cavity.

The etiopathogenesis of the formation of SDC is a complex phenomenon. Crystals can form within the saliva that create a nidus for stone formation. These stones can lead to obstruction of the duct, which can be transient or persistent. In a study conducted by Stojanov IJ et al., [3] out of 177 cases of salivary duct cyst, intra-luminal mucosal stasis was seen in 41.8% cases, incipient calcification in 4.5%, and chronic obstructive sialadenitis in 90.2% cases. However, in most cases, the source of obstruction is often not apparent. In our patient, there was a previous history of small calculi in the parotid duct, which was managed conservatively along with recurrent episodes of pain and swelling while eating, suggestive of chronic sialadenitis. This would have probably led to sialocyst formation. However, there were no calculi noted at the time of preoperative imaging or intra-operatively.

Contrast-enhanced CT (CECT) is often the initial investigation done to delineate the extent of swelling and assess the duct anatomy related to parotid and the surrounding vascular structures. CT scan often helps differentiate these lesions from parotid gland cysts, where the hypodense lesion will be visualised within the gland. Wall thickening may be observed in complicated situations such as haemorrhage or infection. CT scan in our patient showed a well-defined cystic lesion separate from the parotid gland, which helped us arrive at the diagnosis. There were no signs of malignancy.

Fine needle aspiration cytology (FNAC) is very useful for confirming the diagnosis and ruling out malignancy. The rate of inadequate sampling and false-negative results is higher in cystic lesions than in solid tumours [4].The diagnostic value of FNA can be increased if the sampling is done from the solid debris after drainage of cyst fluid [5]. It is necessary to subject all the cystic lesions of the salivary gland to FNA or histopathology, as all neoplasms were predominantly cystic. Histological investigation paves the way to the final diagnosis and should be carefully evaluated. The histopathology of SDC is diverse, ranging from focal areas of the cuboidal or columnar epithelium to areas of metaplasia.

The treatment concerned with the non-neoplastic cyst is observation, as most patients are asymptomatic, and the development of malignancy is quite rare. Ong CA et al., [6] have performed mucocele excision and superficial parotidectomy for parotid duct mucocele without complication or recurrence. Similarly, Dadaci et al. [2] have performed superficial parotidectomy and cyst excision for parotid duct cyst in a child. Parotidectomy for a simple localized benign cystic lesion is morbid and includes the risk of injuring the facial nerve. In our patient, we proceeded with intraoral drainage and Marsupialization of the cyst under local anaesthesia as described. This technique can be safely employed for distal cystic lesions around the opening of the parotid duct, as the more proximal lesions are difficult to access intraorally.

Conclusion

Isolated cysts of parotid duct rather than parotid gland is a rare differential which should be kept in mind in patients presenting with cheek swelling. Marsupialization obviates the need for parotidectomy in the simple cystic lesion of the parotid duct, unlike the cystic lesion in the gland per se. The simplicity and lack of major complications make it an effective treatment for salivary duct cysts.

Author Contribution

BB- writing the initial draft, RS- Data collection, Revising the draft, KR, NS- Data conceptualization. All the authors revised the final draft before submission.

Declarations

Conflict of interest

The authors declare that there are no conflict of interest.

Ethical Statement

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed Consent

Informed consent was obtained from the Patient for publication.