Management of a rare case of parapharyngeal lipoma presentation of case

Abstract

Introduction and importance

Parapharyngeal masses are rare but critical because of their deep location and their important anatomical relationships with the surrounding structures. Their management poses a challenge in terms of etiological diagnosis and adequate therapeutic approach. The clinical and especially the radiological examination have an important role not only for the diagnosis but also for the determination of the appropriate management and for the orientation towards the nature of the mass.

Case presentation

We present the case of a 44-year-old man with a parapharyngeal lipoma that caused mainly obstructive sleep apnea syndrome. Once in our structure after a radiological examination (MRI and CT scan), a decision for surgical management was made. Surgery consisted on a combined cervical and endobuccal approach. The follow-up showed an effective result with the total resolution of the discomfort caused by the mass, which improved the patient's quality of life.

Clinical discussion

Tumors in this space represent less than 1 % of all head and neck tumors and are usually benign. Symptoms leading the patient to consult a doctor only appear after a significant volume of the mass, which makes the severity of this pathology. Imaging, namely CT and MRI, should be requested systematically in case of suspicion of any parapharyngeal mass.

Several surgical approaches are described in the literature, the choice between them depends on the nature of the mass, its location and especially its extension, hence the interest of preoperative imaging.

Conclusion

The main take-away lessons are the great value of imaging in the diagnosis and treatment of parapharyngeal space masses, the relationships of this region and its content make the surgery very delicate, so it's so important to choose the appropriate surgical approach.

Highlights

• •Parapharyngeal masses are rare but critical given the deep locality and the close proximity to the surrounding structures.
• •Parapharyngeal masses are usually evident clinically when of large volume, which can make their management problematic
• •CT and MRI are the most useful preoperative imaging to determine the location, extension and orientation of the mass
• •Several surgical approaches are possible but combined approaches are the safest and most effective for the removal of large masses
• •We illustrate this consideration in our presentation of case of an intramuscular parapharyngeal lipoma in a 44-year-old man with obstructive sleep apnea

1. Introduction

Parapharyngeal tumors are a rare tumor (less than 1 % of all head and neck tumors) which develop at the expense of the anatomical structures of the parapharyngeal region, including adipose tissue, vessels, nerves, lymph nodes and salivary tissue (deep lobe of the parotid gland or an ectopically positioned accessory salivary gland) [1].

These tumors are usually benign, and present a double challenge, clinically they are only expressed after a large volume by indirect signs related to a bulging of the posterior pharyngeal wall or a narrowing of the pharyngeal lumen; then therapeutically because of their deep location and important anatomical relationships, which explains the importance of a detailed pretherapeutic imaging, that conditions the choice of the surgical approach [2].

Our study describes the successful management of a fatty tumor of the parapharyngeal space. The patient had initially a poor quality of life with mainly obstructive sleep apnea syndrome, which is no longer the case after surgery.

This case series has been reported in line with the SCARE 2020 criteria [3].

2. Case report

This is a study of a 44-year-old male patient operated on for a retropharyngeal tumor in our ENT and cervico-facial surgery department. The patient was referred from another hospital.

The mass effect that prompted the patient's consultation was responsible for nocturnal snoring and permanent daytime fatigue which appeared gradually over the last 8 years, in addition to obstructive sleep apnea which appeared 6 months ago. No signs of mixed nerve damage were reported.

He had no history of chronic disease, no previous medications, no allergies or toxic use, and no family history of genetic disease.

On physical examination; the patient was in good general condition.

There was a soft tumefaction in front of the parotid lodge that lifts the ear lobule, appeared 2 years ago before the consultation, progressively increasing in volume (Fig. 1).

Fig. 1.

The tumefaction in front of the parotid lodge that lifts the ear lobule.

The endobuccal examination shows an oropharyngeal mass pushing back the soft palate and uvula (Fig. 2).

Fig. 2.

The oropharyngeal mass pushing back the soft palate and uvula.

At Nasofibroscopy wee see a mass of the cavum reaching the level of the choanae (Fig. 3); the epiglottis was deviated backwards and the vocal cords were mobile. No endoscopic biopsy was taken.

Fig. 3.

Nasofibroscopy: The mass of the cavum reaching the level of the choanae.

The challenge was to determine the nature, location and extension of the mass.

CT showed a process in the retropharyngeal region, causing a mass effect on the soft palate and extending to the nasopharynx (Fig. 4).

Fig. 4.

CT scan in axial section showing the process and its extension.

MRI showed an expansive process (Fig. 5) which is effaced on fat saturation sequences (Fig. 8) with a T1 and T2 hypersignal, developed in the retropharyngeal region, with extension to the rhinopharynx (Fig. 6, Fig. 7) which is collapsed and pushed back to the right, with a T1 and T2 hypersignal. The process extends 92 × 40 mm sagittally (Fig. 5) and 60 × 27 mm axially without affecting the pterygoid muscles and parotid glands.

Fig. 5.

MRI in sagittal section showing the extension in length.

Fig. 8.

MRI in axial section in FAT-SAT sequence showing the fatty nature of the mass.

Fig. 6.

MRI in axial section showing width extension.

Fig. 7.

MRI in axial section showing extension to the Rhinopharynx.

Thus, MRI allowed us to be oriented towards the fatty nature of the mass and both MRI and CT scan allowed us to determine the location and extension.

The patient was operated on by an ENT specialist using a combined cervical and endobuccal surgical approach, after being placed in dorsal decubitus with his head in hyperextension.

The cervical approach required a skin incision from the tip of the chin to the tip of the mastoid (Sebileau-Carrega incision). The subcutaneous detachment revealed the submandibular gland, which was dissected and ablated; then the XII nerve, the lingual nerve and the jugulo-carotid axis were all seen and respected with a ligation of the thyro-lingual-facial venous trunk and the facial artery. Following this, a fatty mass was found in the deep spaces of the face, extending upwards to the retropharyngeal space in front of the nasopharynx and the oropharynx. The endobuccal approach after placement of a mouth opener and an incision opposite the pharyngeal bulge on the right velar mucosa, allowed a direct approach to the mass. The two surgical approaches allowed good exposure of the mass which was dissected and removed.

The anatomopathological findings were:

- Parapharyngeal mass: Morphological appearance of an intramuscular lipoma (Fig. 9).

Fig. 9.

The histological section showing lobulated adipocyte proliferation.

- Submaxillary gland: Chronic non-specific inflammatory.

- Absence of malignancy.

In immediate postoperative period, no hemorrhage or signs of nerve damage were reported. The patient has received prophylactic antibiotics for 10 days due to the severity of the surgery.

At the follow-up consultations 1 month after the surgery, we note a disappearance of the swelling in front of the parotid lodge (Fig. 10), and the patient reports a clear recovery from snoring and obstructive sleep apnea, leading to a better quality of life.

Fig. 10.

Disappearance of the swelling in front of the parotid lodge.

At Nasofibroscopy, we notice a free passage of the upper airways from the nasopharynx to the oropharynx with a normal position of the epiglottis (Fig. 11).

Fig. 11.

The upper airways from the nasopharynx to the oropharynx are liberated.

3. Discussion

Tumors of the parapharyngeal space are account for 0.5–1 % of all tumors of the head and neck. They are malignant in only 14–30 % of cases, of which 45 % develop from the salivary glands [1].

In terms of nature; we note salivary gland tumors (principally the parotid gland (in 90 % of cases, the histological type found is pleomorphic adenoma)), tumors of nervous origin (Schwannomas, neurofibromas and ganglioneuromas (these are the most common after salivary tumors)), paragangliomas (highly vascularized, arising from the paraganglionic cell which is of neuroectodermal origin and has a chemo and baroceptor function, they are located mainly at the tips of nerves IX, X); hemopathies (lymphoma) [2].

Symptoms related to tumor volume are dysphagia, pharyngeal discomfort, rhinolalia, and snoring. Pain or signs of nerve damage should make us fear malignancy, especially dysphonia due to recurrent paralysis, rhinolalia due to veil paralysis, and dysarthria due to hemiparalysis of the tongue [4].

On physical examination, the most evocative sign is an oropharyngeal mass, for which the characteristics must be specified, in particular a displacement of the tonsil and the soft palate [5].

CT is the first-line examination.

It allows a good visualization of the tissues of the parapharyngeal space and gives information on the location, the aspect, the contours and the vascularization of the tumor. It also provides a good visualization of the bony framework of this space. On the other hand, CT cannot specify the nature of the tumor, except in the case of paraganglioma which is hypervascularised on CT [6].

MRI shows clearly the anatomical relationship of the tumor with the jugulo-carotid axis, the contacts with the skull base and the existence or not of an endocranial extension.

The most common tumors (pleomorphic adenomas, nerve tumors, and paragangliomas) can be differentiated by T1 and T2 signal characteristics with or without injection. T1-weighted images allow good visualization of normal anatomy and peri-tumoral fatty borders, T2 images visualize the tumor margins and the tumor-muscle interface [7].

The principal differential diagnoses are aneurysms of the internal carotid artery (CT shows a rounded hypodense mass, with variable enhancement), aneurysms of the internal carotid artery (On CT, it appears as a hypodense mass, circled by the contrast medium and following the path of the vein), vascular malposition (constitutional or consecutive to advanced arteriosclerosis) and abscesses (complicating nasopharyngeal or tonsillar infections) [8].

The treatment of choice is surgical. The endobuccal approach alone is generally used to perform a biopsy in cases of suspected lymphoma, or for the removal of small masses of salivary origin. Dissection of the mass is carefully performed with a spatula or finger [9].

The cervical approach consists of making an incision from the mastoid process to the greater cornua of hyoid bone. An anterior or posterior enlargement can be performed through a parotidectomy incision to locate the facial nerve. It is also possible to perform a mandibulotomy to preserve the inferior alveolar nerve [10].

The transparotid approach is mainly used for parotid tumors with retropharyngeal expression. The facial nerve must be located and the inferior polar parotidectomy realized. The procedures for approaching the parapharyngeal space and exposing the mass are: Section of the stylomandibular ligament and ligation of the external carotid artery as well as resection of the styloid process which can facilitate this operative time. The parapharyngeal extension is removed with the finger and the dissection is carried out step by step. Care should be taken not to fragment the mass, as the exit into the field of the contents of a pleomorphic adenoma may be the cause of a subsequent recurrence [11].

The cervico-parotid approach combines the advantages of the two previous approaches. It is the one most often used, as it allows a safer exposure of the vasculo-nervous elements. This technique is used in cases of malignant parotid tumors, highly situated nerve tumors and large paragangliomas of the vagus nerve. The combined transoral-external approach is for the removal of large tumors, the tumor dissection is done externally and the removal is performed through the mouth [12].

The combined cervical transpharyngeal and cervical transmandibular approach is reserved for large or vascular tumors, which allows optimum control of the retrostylial spaces and the base of the skull. The cervical incision is extended above the mandibular symphysis with labial section besides an incision from the glosso-gingival sulcus to the anterior pillar. The mandibulotomy is realized vertically in front of the emergence of the inferior dental nerve [13].

The evolution is generally good in the case of a benign, well limited and extirpable tumors.

However, complications may occur, depending on the histological nature of the lesion, its size and its anatomical relationship with the large vessels and cranial nerves. Swallowing disorders, inhalation pneumopathy (after surgery on paragangliomas of the vagus nerve) and hemorrhage during or after the surgery are the most common complications [14].

4. Conclusion

Retropharyngeal masses are rare, most of them are asymptomatic for a long time and are therefore voluminous at the time of diagnosis.

Pre-therapeutic evaluations are required, including a CT scan with injection of contrast media and an MRI which allows to be oriented to the nature of mass in certain cases before an anatomopathological certitude diagnosis.

The treatment of choice is surgical, with several simple or combined approaches described.

The nature of the parapharyngeal mass with its size and anatomical relationships as well as the surgical efficacy are the determinants of the choice of surgery approach as well as the postoperative evolution.

Provenance and peer review

Not commissioned, externally peer-reviewed.

Ethical approval

Ethical approval has been exempted by our institution.

Funding

None.

Author contribution

Loudghiri Myriam: Study concept and writing the paper

Saout Arrih Badr: Corresponding author and writing the paper

Oukessou Youssef: Study concept and correction of the paper

Rouadi Sami: Study concept and correction of the paper

Abada Reda: Study concept and correction of the paper

Mahtar Mohamed: Study concept and correction of the paper

Guarantor

Saout Arrih Badr

Research registration number

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Conflict of interest statement

The authors declare having no conflicts of interest for this article