Extracapsular dissection of the parapharyngeal space for a pleomorphic adenoma: a 10-year review.

YBJOM-4204; No. of Pages 6

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British Journal of Oral and Maxillofacial Surgery xxx (2014) xxx–xxx

Extracapsular dissection of the parapharyngeal space for a pleomorphic adenoma: a 10-year review Yuxing Guo, Chuanbin Guo ∗ , Lei Zhang, Guangyan Yu Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, People’s Republic of China Accepted 22 February 2014

Abstract Pleomorphic adenomas of the parapharyngeal space are difficult to remove with a margin of normal tissue. We reviewed 29 cases of extracapsular dissection of a parapharyngeal pleomorphic adenoma and found that extracapsular dissection does not increase the probability of recurrence of the tumour. © 2014 Published by Elsevier Ltd. on behalf of The British Association of Oral and Maxillofacial Surgeons.

Keywords: Extracapsular dissection; Parapharyngeal space; Pleomorphic adenoma

Introduction The parapharyngeal space is a deep anatomical space in the shape of an inverted pyramid, with the greater cornu of the hyoid bone at its apex. The floor is the base of the skull.1 About 80% of tumours of the parapharyngeal space are benign. Tumours of the salivary gland are the most common neoplasms, and pleomorphic adenoma the most usual histological type.2 About 80% of salivary gland neoplasms are found in the parotid gland, with pleomorphic adenoma being the most common subtype.3 Before the 1930s intracapsular enucleation of the tumour from the gland was the standard treatment for a pleomorphic adenoma because of its usually benign clinical course, and because the surgeon did not want to damage the facial nerve.3 Superficial parotidectomy became the standard operation after the seminal work of Patey and ∗ Corresponding author at: Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing 100081, People’s Republic of China. Tel.: +86 10 62179977; fax: +86 10 62173402. E-mail addresses: [email protected] (Y. Guo), [email protected] (C. Guo), zhlei [email protected] (L. Zhang), [email protected] (G. Yu).

Thackray, in which they showed that the capsule that encased the pleomorphic adenoma was partly incomplete.4 This histological finding was immediately accepted as the rational explanation of the relatively high incidence of recurrent tumours that had been noticed during previous decades.4,5 About 80% of parotid tumours lie on the facial nerve, and as the facial nerve must be preserved if at all possible, the tumour must be dissected along its capsule with, in some cases, no margin of normal tissue.4,6 If the tumour originates from the deep lobe of parotid gland, the situation becomes more complicated. As the tumour grows, the facial nerve is stretched like a bowstring over its surface. However, such cases are not associated with a high incidence of recurrence.4,5 George and McGurk, and Gleave et al. thought that the high incidence of recurrence in the 1930s and 50s resulted not from the biological properties of the pleomorphic adenoma, but rather from the surgical technique used.4,7 Some authors reported their experiences of extracapsular dissection for pleomorphic adenomas of the parotid as being similarly effective but with fewer side effects than superficial parotidectomy.3,4,8,9 Because the connective tissue around the parapharyngeal space is loose, the tumour may easily enlarge, being adjacent to the carotid artery, the jugular vein, and the cranial

http://dx.doi.org/10.1016/j.bjoms.2014.02.019 0266-4356/© 2014 Published by Elsevier Ltd. on behalf of The British Association of Oral and Maxillofacial Surgeons.

Please cite this article in press as: Guo Y, et al. Extracapsular dissection of the parapharyngeal space for a pleomorphic adenoma: a 10-year review. Br J Oral Maxillofac Surg (2014), http://dx.doi.org/10.1016/j.bjoms.2014.02.019

Age (years)

Primary/recurrence

Preoperative image

Diameter of tumour (cm)

Origin of tumour

Operative approach

Bleeding (ml)

Operating time (min)

Duration of follow-up (years)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

F F F F M M F F M F F F F F M M M M F M M F M F F M F M M

45 69 34 42 45 36 26 20 23 63 55 37 33 64 25 40 27 42 50 24 23 55 23 37 39 31 48 28 38

Recurrence Primary Recurrence Primary Recurrence Primary Recurrence Primary Primary Recurrence Primary Recurrence Primary Primary Primary Primary Primary Primary Primary Primary Primary Primary Primary Primary Primary Primary Primary Recurrence Primary

CT CT CT CT CT CT CT CT CT CT CT CT CT CT CT CT CT/DSA CT CT CT CT CT CT MRI CT CT CT/MRI CT/PSG MRI

4 5 4 6 3 4 4 3 2 4 3 2 5 4 5 6 4 5 6 5 6 5 7 9 4 6 4 6 4

DL DL DL DL DL DL DL MS DL DL MS DL DL DL DL DL MS DL DL MS DL DL DL DL DL DL DL DL DL

MN MN MN MN MN MN MN TO TC TC MN MN MN MN MN MN MN TP MN MN MN MN TP MN MN MN TP MN MN

600 300 150 80 400 400 1000 10 20 100 120 750 150 100 200 280 50 80 200 200 200 280 1300 180 400 150 50 250 600

225 105 150 105 195 140 225 20 60 180 90 240 90 150 190 175 140 150 100 90 210 150 230 135 195 180 135 240 225

1.00 1.00 1.00 1.00 1.00 1.50 2.00 2.00 2.00 3.00 3.00 3.00 3.00 4.00 4.00 4.00 3.00 4.00 4.00 4.00 5.00 6.00 5.00 1.50 8.00 8.00 9.00 7.00 5.00

151 (11.0)

3.66(0.421)

Mean (SD)

4.66(0.278)

279 (59.2)

Complications

ILN ILN

Frey syndrome Numbness of tongue

TFP

TFP Numbness of tongue ILN TFP Wound infection

TFP Numbness of tongue

MN, mandibulotomy; TP, transparotid; TC, transcervical; TO, transoral; DL, deep lobe of parotid gland; MS, minor salivary; TFP, temporal facial paralysis; ILN, numbness of inferior lip.

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Table 1 Details of patients.


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nerves IX–XII.10 Manipulation in this limited space carries a high risk of damaging a peripheral neurovascular structure, and resection of the tumour often required extracapsular dissection.1,5 We have studied the incidence of recurrence and postoperative complications after extracapsular dissection for pleomorphic adenoma of the parapharyngeal space and present a retrospective review of our 10-year experience of it.

Patients and methods Twenty-nine patients with pleomorphic adenomas involving the parapharyngeal space were treated at our hospital from 2001 to 2010. Preoperative signs and symptoms, histopathological diagnosis, preoperative radiographic evaluation (computed tomography (CT) and magnetic resonance imaging (MRI)), the surgical approach, and the outcome were recorded if available. Tumours of the deep lobe of the parotid were distinguished from extraparotid tumours on radiographic evaluation. Preoperative CT, MRI, ultrasound, carotid angiography, and fine needle aspiration cytology were done selectively. All 29 patients were operated on, and they were followed up by review in the clinic or by telephone contact as needed.

Results There were 13 men and 16 women, mean age 39 (range 20–69) years, 7 of whom were referred from elsewhere having been operated on in the past. The remaining 22 were primary presentations (Table 1). On physical examination most patients had a pharyngeal mass with displacement of the tonsil, or soft palate, or both. As tumours enlarge and extend superiorly, they may cause symptoms related to the Eustachian tube and, rarely, middle ear effusions. As tumours expand medially, nasal obstruction, aspiration, and dyspnoea can develop (Table 2). Patients seldom had pain, trismus, otalgia, or cranial nerve deficits, which are the typical symptoms of malignant tumours. Twenty-five patients with deep-lobe tumours that extended into the parapharyngeal space (22 seen on CT and 2 on MR images, and 1 on both), and 4 minor salivary gland tumours arose within the parapharyngeal space (3 were seen on CT, 1 on angiography, and 1 on both). CT was the most common imaging method used, as it was able to differentiate a parapharyngeal mass in the parapharyngeal space from a tumour of the deep lobe of the parotid or a minor salivary gland. The median diameter of the tumour, as judged by preoperative imaging and intraoperative measurement, was 4.6 (range 2–9) cm. The approaches used to remove the tumours are shown in Table 3. The mean (SD) operative bleeding was 279 (59.2) ml and operating time 151 (11.0) min. The mean

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Table 2 Signs and symptoms of 29 parapharyngeal pleomorphic adenomas. Some patients had more than one of each. No. (%) of tumours Symptoms Pharyngeal mass Neck mass Pain Dysphagia Voice change Sensation of foreign body Change in hearing Dyspnoea

19 (66) 2 (7) 1 (3) 3 (10) 1 (3) 3 (10) 3 (10.3) 4 (13.8)

Signs Pharyngeal mass Mass in neck Parotid mass Trismus

23 (79) 5 (17) 3 (10) 1 (3)

duration of postoperative hospital stay was 7 (6–8) days. Among the group who had a mandibulotomy approach, no patient required a tracheostomy. All patients were followed up at regular intervals, including radiographic follow-up at 3–6 months or as clinically indicated. Neurological complications were the most common (Table 1). There were no salivary fistulas, permanent facial paralysis, or episodes of trismus. The mean follow-up among the 29 patients was 4 years (range 2–9). Fourteen patients were followed up for more than 4 years. One patient relapsed, and had no recurrence after reoperation. One patient died during follow-up of a cerebral haemorrhage.

Case report A 42-year-old woman was referred to us with a diagnosis of tumour in the right parapharyngeal space shown on CT at another hospital (Supplementary Fig. 1). Because of the deep position, large size, and intimate relation with the carotid sheath, we did an enhanced CT and 3-dimensional reconstruction of the tumour, vessels, and cranial bone on navigation software (Supplementary Figs. 2–3). Supplementary Figs. 1–3 related to this article can be found, in the online version, at http://dx.doi.org/10.1016/ j.bjoms.2014.02.019. The patient was operated on through a mandibulotomy approach, which can help to expose the tumour well, and the intraoperative CT navigation system was used to judge its site and extent to prevent neurovascular injury (Supplementary Figs. 4–7, Fig. 1). Mandibular osteosynthesis required 2 titanium plates. Her postoperative course was uneventful and she was discharged and began oral feeding on postoperative day 7 with no difficulties. At the 24 months’ follow-up she was free from disease and on assessment cosmesis was excellent (Supplementary Fig. 8).



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Table 3 Surgical approach and site of tumour in 29 patients with pleomorphic adenomas. Surgical approach

Deep lobe of parotid

Mandibulotomy Transcervical Transparotid Transoral Transoral + transparotid Mandibulotomy + transparotid Total

Minor salivary

“Dumb-bell”

Tail

Retromandibular

1 – 2 – – – 3

3 1 – – 1 – 5

14 1 – – – 2 17

Fig. 1. The excised specimen.

Supplementary Figs. 4–8 related to this article can be found, in the online version, at http://dx.doi.org/10.1016/ j.bjoms.2014.02.019.

Discussion The most common primary tumours of the parapharyngeal space are salivary gland neoplasms that originate from the deep lobe of the parotid gland or from minor salivary glands.2 Tumours in the deep lobe of the parotid are defined as arising from an area medial to the facial nerve, and they have various paths of growth. Only a tumour that is located medial to the mandible can be called a tumour of the parapharyngeal space.2,11 A tumour of the deep lobe of the parotid may have an external component that is palpable anterior to the tragus, and have a pharyngeal component that extends through the stylomandibular tunnel into the parapharyngeal space in a “dumb-bell” shape (Supplementary Fig. 9).1,12 Pleomorphic

3 – – 1 – – 4

adenomas can also arise from the retromandibular portion of the parotid gland (Supplementary Fig. 10). The tumour expands into the parapharyngeal space from the place where the external carotid pierces the parotid fascia inferior to the stylomandibular ligament, and displaces the tonsil and palate.13 As these tumours grow and enlarge they may also become palpable between the mandible and the mastoid process, displace the soft palate, and obstruct the nasopharynx.1 Supplementary Fig. 9 and 10 related to this article can be found, in the online version, at http://dx.doi.org/10.1016/ j.bjoms.2014.02.019. Another origin of tumours of the parapharyngeal space is the tail of the superficial lobe of the parotid (Supplementary Fig. 11). These tumours can form round lesions that grow medially and cranially to present as masses in the parypharyngeal space.13 The parapharyngeal component is generally the largest, but the tumours also have an external palpable component situated posterior and inferior to the angle of the jaw.1 Supplementary Fig. 11 related to this article can be found, in the online version, at http://dx.doi.org/10.1016/ j.bjoms.2014.02.019. The final ectopic salivary tissue is also a source for salivary neoplasms of the parapharyngeal space, and this salivary tissue lies in the space with no obvious connection to the deep lobe of the parotid gland (Supplementary Fig. 12).14 Parapharyngeal salivary tumours may also arise from the serous glands beneath the parapharyngeal mucosa medial to the superior constrictor muscle. Supplementary Fig. 12 related to this article can be found, in the online version, at http://dx.doi.org/10.1016/ j.bjoms.2014.02.019. It is important to distinguish masses in the deep lobe of the parotid from an ectopic parotid lesion, as it is the primary factor in deciding the surgical approach that will be used to excise the tumour. Both CT and MRI can distinguish a tumour of the deep lobe of the parotid from an extra-parotid tumour of the minor salivary glands that is extending into the parapharyngeal space, from evidence of the fatty layer between the tumour and the pharyngeal wall.15 MRI is superior to CT for this, and it is also more valuable in assessing if the tumour is infiltrating intracranially, particularly when the base of the skull is involved.16 The three-dimensional CT reconstruction can show more detail about the relation between the tumour


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Table 4 Details of patients in whom the pleomorphic adenoma recurred in the parapharyngeal space. Age at this operation (years)

Age at previous operations (years)

Last operative approach

Operative approach

Rupture of tumour capsule

Recurrence

1

45 34

5

45

7 10 12

26 63 37

29

28

Transcervical Transoral Transoral Transparotid Transfacial Transparotid Transparotid Transoral Transoral Transoral Transoral Transoral

TP + MN

3

25 39 25 28 31 42 44 21 56 22 30 26

No – Yes – – Yes – Yes Yes Yes – Yes

No – No – – Yes – No No No – No

Case no.

MN + half-coronal

MN MN MN MN MN

MN, mandibulotomy; TP, transparotid; TC, transcervical.

and the surrounding structures, which helps the surgeon to select the surgical approach.17 Preoperative knowledge of the histopathology of a tumour of the parapharyngeal space is also important for surgical planning. Fine-needle aspiration biopsy can be helpful to avoid the implantation or recurrence.18 A navigation-guided needle biopsy technique used in our unit, can help get pathological results safely, and provide valuable information for decision-making.18 The surgical goal should be to remove the lesion intact without rupture. Recurrence is possible, particularly if the capsule breaks and tumour spills. In one reported series of tumours of the parapharyngeal space, rupture or spillage was the most common complication, and occurred in 37 of 172 patients. Of these 37 patients, 12 developed recurrences.10 Removal of a pleomorphic adenoma from the parapharyngeal space usually involves extracapsular dissection. The loose areolar tissue in the parapharyngeal space may permit extracapsular dissection with little risk of spillage, and these may have a lower recurrence rate than would occur in comparable series of tumours of the superficial lobe. Spillage can be lessened when the surgical exposure is better, so the ideal operative approach should afford an adequate surgical field in which to complete extracapsular dissection without spillage.19 We used 4 surgical approaches in our series: transoral, transcervical, transparotid, and transmandibular, and the selection was related to the origin and site of the tumour. The transcervical approach, as has been described by several authors, provides direct access to the parapharyngeal space, with adequate exposure of the neurovascular structures. It can also be used for a tumour of the parotid tail. When the tumour is larger than 8 cm or extends to the skull base, mandibulotomy at an angle of the mandible can help improve exposure of the neurovascular structures.11,15,19 Although some authors advocate a transparotid approach for such tumours, we think that the main use for the technique is for the “dumb-bell” type of tumour. These are removed through a transparotid approach and the facial nerve is

identified first, and freed completely before the tumour is dissected. The dislocation of the mandible anteriorly can help to add moderate space for removal of the tumour.1 Routine use of the transparotid approach is associated with substantial cosmetic defects and increased risk of temporary or permanent facial palsy.4,5,7,8,12 We prefer to use a mandibular swing through a paramedian or premental foramen mandibulotomy to preserve the inferior alveolar nerve for minor salivary, retromandibular, and recurrent tumours.20 This approach does not include visualisation of the facial nerve. In this group of patients, 23/29 patients (79%) required the mandibulotomy approach. A pleomorphic adenoma of the minor salivary glands is rare in the parapharyngeal space. The transoral approach has been reported to be effective for removing selected benign, minor salivary gland tumours that have extended into the parapharyngeal space. However, this approach provides poor exposure, a lack of wide access to regional vessels and nerves, and a high risk of spillage with possible recurrence.5,14 Retromandibular tumours usually extend well into the skull base and are large. In this series we used the mandibulotomy approach for 16 patients. Two had superficial parotidectomy and dissection of the facial nerve first, and then removal of the tumour with visualisation of the facial nerve combined with mandibulotomy. No patient developed a salivary fistula, permanent facial paralysis, or trismus postoperatively. There have been no recurrences in our series when this approach has been used. Accurate reapproximation of the skin of the lip and chin is essential to obtain an aesthetically acceptable scar. Seven of our 29 patients had recurrent pleomorphic adenomas. Of these, 6 were treated through a transoral approach at least once, and one patient had a transparotid approach (Table 4). The time of recurrence was less than 1 year from the previous operation. All 7 patients had the recurrent tumour removed through a mandibulotomy approach, only one of whom developed a recurrence 6 months later, and had another operation after which the histopathological


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examination showed myoepithelial carcinoma. Until now there has been no evidence of recurrence after radiotherapy (66 Gy). We conclude that the mandibulotomy approach can fully expose the operative field for removal of a pleomorphic adenoma of the parapharyngeal space, and extracapsular dissection can completely remove the tumour with protection of the surrounding neurovascular structures. Extracapsular dissection of the tumour does not increase the probability of recurrence, and is the choice for excision of a pleomorphic adenoma of the parapharyngeal space.

Conﬂict of interest There is no conflict of interest.

Acknowledgement The article written process was supported by the National High Technology Research and Development Program of China (863 Program,2012AA041606).

References 1. Olsen KD. Tumors and surgery of the parapharyngeal space. Laryngoscope 1994;104(5 Pt 2 Suppl. 63):1–28. 2. Mendelsohn AH, Bhuta S, Calcaterra TC, Shih HB, Abemayor E, St John MA. Parapharyngeal space pleomorphic adenoma: a 30-year review. Laryngoscope 2009;119:2170–4. 3. Albergotti WG, Nguyen SA, Zenk J, Gillespie MB. Extracapsular dissection for benign parotid tumors: a meta-analysis. Laryngoscope 2012;122:1954–60. 4. George KS, McGurk M. Extracapsular dissection – minimal resection for benign parotid tumours. Br J Oral Maxillofac Surg 2011;49: 451–4.

5. Smith SL, Komisar A. Limited parotidectomy: the role of extracapsular dissection in parotid gland neoplasms. Laryngoscope 2007;117:1163–7. 6. Witt RL, Iacocca M. Comparing capsule exposure using extracapsular dissection with partial superficial parotidectomy for pleomorphic adenoma. Am J Otolaryngol 2012;33:581–4. 7. Gleave EN, Whittaker JS, Nicholson A. Salivary tumours – experience over thirty years. Clin Otolaryngol Allied Sci 1979;4:247–57. 8. Dell’Aversana Orabona G, Bonavolontà P, Iaconetta G, Forte R, Califano L. Surgical management of benign tumors of the parotid gland: extracapsular dissection versus superficial parotidectomy – our experience in 232 cases. J Oral Maxillofac Surg 2013;71:410–3. 9. Roh JL. Extracapsular dissection of benign parotid tumors using a retroauricular hairline incision approach. Am J Surg 2009;197:e53–6. 10. Hughes KV, Olsen KD, McCaffrey TV. Parapharyngeal space neoplasms. Head Neck 1995;17:124–30. 11. Kanzaki S, Nameki H. Standardised method of selecting surgical approaches to benign parapharyngeal space tumours, based on preoperative images. J Laryngol Otol 2008;122:628–34. 12. Chu W, Strawitz JG. Parapharyngeal growth of parotid tumors: report of two cases. Arch Surg 1977;112:709–11. 13. Carr RJ, Bowerman JE. A review of tumours of the deep lobe of the parotid salivary gland. Br J Oral Maxillofac Surg 1986;24:155–68. 14. Hakeem AH, Hazarika B, Pradhan SA, Kannan R. Primary pleomorphic adenoma of minor salivary gland in the parapharyngeal space. World J Surg Oncol 2009;7:85. 15. Bozza F, Vigili MG, Ruscito P, Marzetti A, Marzetti F. Surgical management of parapharyngeal space tumours: results of 10-year follow-up. Acta Otorhinolaryngol Ital 2009;29:10–5. 16. Irish JC, Gullane PJ, Gentili F, et al. Tumors of the skull base: outcome and survival analysis of 77 cases. Head Neck 1994;16:3–10. 17. Guo Y, Guo C. Application of three-dimensional reconstruction of the enhanced CT in infratemporal fossa and parapharygeal space tumors. Beijing Da Xue Xue Bao 2011;43:148–50 [in Chinese]. 18. Oliai BR, Sheth S, Burroughs FH, Ali SZ. Parapharyngeal space tumors: a cytopathological study of 24 cases on fine-needle aspiration. Diagn Cytopathol 2005;32:11–5. 19. Khafif A, Segev Y, Kaplan DM, Gil Z, Fliss DM. Surgical management of parapharyngeal space tumors: a 10-year review. Otolaryngol Head Neck Surg 2005;132:401–6. 20. Yu GY, Zhang L, Guo CB, Huang MX, Mao C, Peng X. Pre-mental foramen mandibulotomy for resecting tumors of tongue base and parapharyngeal space. Chin Med J (Engl) 2005;118:1803–7.


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