Transoral Excision of a Huge Parapharyngeal Space Pleomorphic adenoma: A Possibility of Changing the Surgical Consideration to a Minimally Invasive Approach

Case Report

Transoral Excision of a Huge Parapharyngeal Space Pleomorphic adenoma: A Possibility of Changing the Surgical Consideration to a Minimally Invasive Approach

Corresponding authorDr. Mutlaq Al-Sihan, Consultant ORL-HNS, Reconstructive HNS & Facialplasty, Chairman of ORL-HNS Department Al-Jahra Hospital Kuwait, Tel: +965 50132311; Email:
Parapharyngeal space(PPS) primary tumors are rare and differ in nature and where they lie in the PPS. The type, the position and size of the tumor impacts the decision for type of surgical approach. We present here the case of a 35-year-old male with a very large pleomorphic adenoma arising from PPS, measuring 7.8x6x4.6 cm. A transoral surgical approach was done with uneventful intraoperative and postoperative complications. Here in Kuwait, we are introducing the possibility of changing the surgical consideration to a minimally invasive approach in selected benign PPS masses. This case report is the first in the literature worldwide to mention complete excision of such a large lesion using this approach.
Keywords:Prarapharyngeal space; Pleomorphic adenoma; transoral approach   
Primary PPS tumors comprise less than 1% of head and neck tumors. The majority are benign and only 20% are malignant tumors [1]. Due to the variable anatomical structures in the PPS, different types of tumors can arise within this space, whether malignant or benign tumors. Surgery is the mainstay treatment for PPS tumors with different surgical approaches. According to the literature, transoral excision of benign PPS masses is only done with certain criteria [2], which was not the situation in our case report.

Case Report

A 35-year-old male presented to our casualty with a history of dysphagia and dysphonia beginning a couple of weeks previous. He was diagnosed as left-sided quinsy and was admitted for intravenous antibiotics and incision and drainage under local anaesthesia, but no pus collection was present. In the ward with proper history taking, the patient mentioned that he had a history of unilateral nasal obstruction for about five months followed by progressive left-sided hearing loss that resulted in a voice change. His wife mentioned that he recently started to snore and described symptoms of obstructive sleep apnea. On examination, the patient had a muffled voice. The oral cavity showed a huge left-sided mass displacing the uvula and tonsil that was occupying the left soft palate,oropharynx and hypopharynx (Figure 1).

Figure 1. Preoperative picture of the left parapharangeal mass.
Left ear otoscopy showed a dull tympanic membrane featuring secretory otitis media. No palpable lymph nodes were detected. The rest of the examination was normal. Blood tests were done and showed normal results. Radiological evaluation was done starting with a neck ultrasound followed by a head and neck CT scan that showed a well-defined soft tissue mass in the left PPS measuring 7.9 x 5.4 cm with a differential diagnosis of left parapharangeal pleomorphic adenoma or a mass of neuroginic origin, for example schwannoma. MRI and MRA showed a soft tissue mass lesion of a left parapharyngeal space lesion measuring 7.9×4.3×6.1cm and extending from the roof of the nasopharynx until the submandibular space, posteriorly displacing the styloid and carotid vessels (Figure 2).

Figure 2. MRI with contrast of the head and neck showing the huge mass coronally and axially.
Fine-needle aspiration cytology showed pleomorphic adenoma. Surgical options were discussed with the patient, explaining the procedure, complications (including converting the transoral route to a transcervical approach,and the possibility of need for a tracheostomy and mandibulotomy), and the follow- up plan.

Figure 3. MRI with contrast of the head and neck showing the huge mass coronally and axially.

A mass excision was done transorally with a left side incision through the soft palate superiorly and laterally, preserving the tonsil, major blood vessels and nerves (Figure 3). Excision of the whole mass was done, which was about 7.8x6cm with its capsule and contents,with no remnants left. The wound was closed with subcutaneous and interrupted sutures after confirming field hemostasis. The patient was discharged home three days postoperative with no acute complaints. The postoperative follow-up was uneventful and the patient gradually regained his normal voice, swallowing habit,breathing and hearing (Figure 4).
Figure 4. Intraoperative usage of the transoral approach.
Figure 5. Two weeks postoperative showing normal anatomy pharynx
In the follow-up visit three months postoperatively, the patient was doing well and there were no further complaints. The last radiological CT neck follow-up two years later was done and showed no recurrence (Figure 5).
 Figure 6. CT neck control 2 years later.
TThe parapharyngeal space (PPS) is an inverted pyramid neck space extending from the skull base superiorly to the greater cornu of the hyoid bone inferiorly.It is divided into prestyloid and poststyloid spaces by the fascia joining the styloid process and the tensor veli palatini.Prestyloid space components include the retromandibular portion of the deep lobe of the parotid gland, internal maxillary artery,the mandibular branch of the trigeminal nerve, adipose tissue and lymph nodes.Post-styloid structures include cranial nerves (the accessory nerve I-Hypoglossal nerve XII), internal jugular vein, internal carotid artery, sympathetic chain and lymph nodes [3].Due to the variable anatomical structures in the PPS, different types of tumors can arise within the space whether malignant or benign tumors. Examples include salivary gland tumors (45%), most commonly pleomorphic adenoma of the deep parotid gland or minor salivary glands; neurogenic lesions (25%), mainly neurilemomas followed byparagangliomas(15%); and metastatic lymph nodes [4]. PPS tumors are not commom and they present with different symptoms including neck mass (46%), pain (20%), dysphagia (13%), pharyngeal mass (9%), hoarseness (7%), foreign body sensation (6%), parotid mass (4%), otalgia (4%) and trismus (2%).In our case, as the symptoms progressed over a few months, the patient presented late when the mass size was large enough to be visible in the oral cavity alongside the other symptoms. Laboratory and imaging studies are essential to the management of each individual case. MRI and CT scans are excellent options to differentiate between pathology of prestyloid versus poststyloid spaces, as well as helping in localizing of the tumor and showing its estimated size, extension, involvement of vascular and/or neural structures,and skull base involvement. Fine-needle aspiration cytology can be performed transaorally in tumors that displace the pharyngeal wall or transcutaneously in a palpable neck mass. In a deeply seated parapharangeal mass, CT guided fine-needle aspiration is a good option.Vascular tumors should be excluded with MRI-angigraphy [3]. Surgery is the mainstay treatment for PPS tumors with different approaches depending on tumor size, extent and surgeon experience. Surgical approaches include transoral, transcervical- transparotid, transcervical-transmandibular and infratemporal fossa [5].

The transoral approach in the excision of parapharyngal space (PPS) tumors (including pleomorphic adenomas, the most frequent tumor of the PPS),was first described by Goodwin & Chandler in 1988. It is cited by several series to be the second-  most frequently adopted approach after a transcervical approach [6].Most others consider this approach the most controversial of all approaches to PPS tumors, therefore, it is relatively rarely used and is third in frequency (at 17%) after the transcervical approach (40%) and transparotid approach (19%) [7], or is last in frequency (at 2%), after the transcervical approach (63%), cervical-transparotid approach (25%), and transmandibular approach (8%) [8]. Moreover, it is often considered to be even contraindicated because of its limited exposure, with consequent higher risk of complete tumor removal, tumor spillage, and possibility of neural injury or vascular injury (hemorrhage), dehiscence, fistulas and potential neck infection secondary to salivary contamination [9].

The transoral approach to a PPS tumor has been in the past classically limited to small and benign lesions because the surgical approach must guarantee a wide view of the surgical bed for a radical dissection of the tumor, with the lowest risk of injuries to vital structures. Thus, exclusively using this technique (no combination with external approaches) is recommended only in benign tumors < 3 cm, situated in the pre-styloid compartment of the PPS, and which are medially situated so as to be amenable to inspection/palpation in the oropharynx [10].

While it is probably true that the transcervical approach (combined or not with a transparotid route and/or mandibulectomy) increases the theoretical risk of damaging cranial nerves versus the transoral approach, this seems to only hold true for relatively small tumors. The risk level reverses between both approaches when dealing with large tumors.For the same reasons, the combined transoral-transcervical approach should also be avoided.

In our case report, we decided to remove the mass transorally despite its large size and we succeeded in doing so without the need for conversion to an external procedure. No complications occurred intraoperatively or postoperatively, which may occur with other open procedures.These complications can include hematoma,airway obstruction, infection, seroma,visible scars in young patients or face deformity after mandibulotomy and a long hospital stay [3]. The challenge of a minimally invasive approach and the wish to minimize scarring for a young patient postoperatively were impetus for this approach by the surgical team.

According to my experience with this large tumor, my recommendation for the transoral approach is only when the tumor is located very medially, with the tumor size relatively not as important compared with a good mouth opening for exposure of the large tumor,exclusively in the location of the pre-styloid compartment of the PPS and not arising from the deep lobe of the parotid gland. There must be a well-confirmed separation between the tumor situated in the pre-styloid compartment and the internal carotid artery and internal jugular vein situated in the post-styloid compartment.

Our case report concludes by concurring with the opinion that, “A transoral approach for the surgical ablation of any benign PPS tumor of the pre-styloid compartment with certain prerequisites is yet to be established.”


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