Odontogenic myxomas: what is the ideal treatment?

Abstract

There is no consensus regarding the ideal treatment for odontogenic myxomas, an odontogenic mesenchymal neoplasm. Various authors have suggested en bloc resection due to a concern regarding inadequate clearance while others have suggested more conservative treatment. We present a case managed by buccal cortical resection and an iliac crest bone graft. The patient had no recurrence for over 7 years.

Background

The ideal treatment of odontogenic myxomas has not been unanimously agreed on in the literature. This means that different treatment modalities of varying associated morbidities, from curettage and enucleation to en bloc resection, have been reported and recommended in the literature. As the more radical surgical approaches have significant associated morbidities, above all from an aesthetic point of view, it was deemed important to demonstrate a case which was treated successfully without radical resection. We hope that a clearer ‘protocol’ for treatment of such lesions can be established with increased reports in the literature and a robust literature review.

Case presentation

We present the case of a 26-year-old woman presented to Royal Perth Hospital (RPH) in 2008 for a second opinion regarding management of an odontogenic myxoma (OM) in the left body of the mandible. The lesion had previously been diagnosed as an OM approximately 7 years prior in New Zealand; however, no treatment was initiated. The patient reported no symptoms other than a growing swelling on the left side of her face, which was beginning to interfere with her ability to work in a highly visible job (figure 1). She sought the opinion of an otorhinolaryngologist in 2008, who recommended an aggressive surgical approach involving radical segmental resection of the mandible, followed by a vascularised osseocutaneous tissue graft reconstruction. As this treatment would result in significant disfigurement to the patient and end her career, she decided to attend the Oral and Maxillofacial Clinic at RPH for a second opinion.

Figure 1.

Preoperative extraoral view.

On examination, the patient displayed obvious facial asymmetry, with a large swelling on the left side of the jaw. The swelling was diffuse and firm. The overlying skin was normal in appearance, and no lymphadenopathy was found. Intraoral examination revealed a small, firm swelling in the left buccal vestibule (figure 2).

Figure 2.

Preoperative intraoral view.

Investigations

An orthopantomogram (OPG) showed a poorly defined multilocular radiolucency, with fine trabeculation, extending posteriorly from the left first premolar, towards the left angle of the mandible (figure 3). There was no evidence of root resorption. A CT scan revealed destruction of the buccal cortex of the left body of the mandible (figure 4). A trephine bone biopsy was performed, intraoperatively through the buccal cortex, to confirm diagnosis of OM.

Figure 3.

Orthopantomogram showing a poorly defined radiolucency at the left angle of the mandible.

Figure 4.

Preoperative CT scan.

Treatment

The patient accepted surgery. An intraoral buccal approach was used with 34, 35, 35 and 37 extractions under general anaesthesia. A large flap was raised to fully expose the buccal aspect of the lesion and the buccal plate was cut with clearance around the lesion and a fissure burr was used to cut the inter-radicular tooth bony socket plates on their lingual aspects. The lesion was levered out of its bony bed with the inferior alveolar nerve being dissected out of the lesion and left intact (figure 5).

Figure 5.

Intraoperative photograph showing the carefully dissected inferior alveolar nerve.

The surgical site was then cleaned of all myxomatous tissue and the lingual plate cut back to sound bone with a large pineapple burr. The surgical bed of the lesion was then treated with Carnoy’s solution.

A bone graft was harvested from the patient’s right iliac crest and implanted into the mandibular defect. A 16-hole reconstruction plate was used to secure the bone graft and reinforce the resected mandible. The patient was placed in intermaxillary fixation for 6 weeks postoperatively.

Postoperative OPG and CT scans were ordered (figures 6 and 7). The specimen was sent for histopathological analysis and clear margins were confirmed.

Figure 6.

Orthopantomogram showing patient immediately postoperation, with bone graft and reconstruction plate in situ.

Figure 7.

Orthopantomogram showing patient 7 years after surgery.

Outcome and follow-up

The patient has been reviewed at regular intervals since her initial surgery in May 2008 and most recently in March 2015. Following an initial period of numbness and altered sensation, the patient has regained full feeling to her lower left lip, chin, tongue and remaining teeth. Her face is symmetrical and there are no visible scars on her face or body, other than an almost unnoticeable line on her right hip from graft surgery (figure 8). In August 2010, the patient had a CT scan and underwent six trephine biopsies of the bone in the left mandible to ascertain the bone status. The CT report and all biopsies were reported as normal bone with no evidence of recurrence. An OPG has been taken on each occasion at her annual review following surgery, and these X-rays have shown successful integration of the bone graft and no new pathology. The patient is extremely happy with the result and has resumed her work.

Figure 8.

View of patient immediately postoperation.

Discussion

OM is an odontogenic mesenchymal neoplasm. A myxoma is an uncommon connective tissue tumour consisting of scattered stellate cells spread in connective tissue mucin. There is a network of reticulin fibres in this expanse of mucin. Its histological and biochemical features resemble those of Wharton’s jelly, which is found in the umbilical cord of the mature fetus.¹ Crucially, in some OMs, focal areas of fine strands of collagen and blood vessels exhibiting a thin outer zone of hyalinisation are found. In the periphery, the myxomatous tissue penetrates the trabecular spaces, producing islands of residual bone (figure 9).² This feature accounts for the difficulty in conservatively removing the lesion.³

Figure 9.

(A) Microscopic involvement of bone and dental structures by odontogenic myxoma. (B) Proliferation of spindled and stellate cells in a mucoid-rich matrix.

There is a controversy in the literature regarding the most appropriate treatment modality for OM.⁴

The majority occur between the ages of 10 and 50 years. The average age ranges between 25 and 35 years, and there may be a slight female preference. Most are situated in the tooth-bearing areas, and the approximate ratio of maxillary to mandibular lesions has been reported as 3:4. Myxomas of the jawbones tend to be larger in children.⁵

Occasionally, lesions have been found in the ramus and other non–tooth-bearing areas of the jaws and in other facial bones. Additionally, lesions with identical histological features are found in the soft tissues. Studies have been undertaken on the jaw lesions in an effort to prove an odontogenic origin, but this effort has been somewhat unsuccessful.³

Clinically, most lesions are painless, slowly enlarging swellings of the involved bone that sometimes displace teeth. Patients are often aware of these lesions for several years before seeking treatment. Maxillary lesions occur equally in all areas and frequently erode the sinus, often crossing the midline and into the opposing sinus cavity. Mandibular lesions are most commonly found in the molar and premolar areas and often extend into the ramus.³ The OM expands the cortical plates, showing as a smooth enlargement of the alveolar and basal bone. Sometimes, it perforates the cortical plate and produces a bosselated surface. The expanding tumour is soft on palpation when the plates are destroyed and gives an impression of fluctuance.⁵ The absence of a capsule and its proclivity for permeation into marrow spaces is thought to underpin the aggressive nature of this lesion.⁶

Radiographically, the OM may produce several patterns: unicystic, multilocular, more rarely pericoronal and rarely radiolucent-radiopaque. Fine intralesional trabeculation occurs in most of the multilocular examples, as well as some of the unicystic types, as a soap-bubble, honeycomb or tennis-racket pattern. The unilocular types and multilocular types appear with equal frequency. The unilocular varieties tend to be small and are mostly located in the anterior region and the multilocular type in the posterior region. Margins may be poorly or well defined, and border sclerosis have been observed in some cases.⁵

Some authors have recommended more conservative enucleation and curettage to be followed by radical resection if there is a recurrence. This aims to preserve function by retaining the uninvolved structures.⁷ In contrast, some other authors have emphasised the aggressive nature of this tumour and advocated 0.5–1.5 cm margins of resection.^{8 9} Taking into account the aggressivity of OMs as well as the need for functional outcomes for patients, Boffano et al ¹⁰ suggested enucleation and curettage where the diameter of OM is less than 3 cm whereas larger tumours warrant segmental resections.

The most reliable study into such a question would undoubtedly be randomised control trials. However, as OMs are exceedingly rare, such a study would be costly and fraught with difficulty. The above case illustrates the merits of a less than fully radical approach to treatment. In the absence of an evidence-based solution, it is best to follow Zanetti et al in using a conservative approach initially and progressing to peripheral osteotomy if recurrence occurs.¹¹ Resections could perhaps be attempted following a recurrence subsequent to a conservative surgery. It has been reported that the main cause for recurrence is thought to be incomplete removal rather than an intrinsically aggressive pathology associated with this tumour.¹² Indeed, the results of a literature review by one of the authors lend credence to this conclusion. In this review, no significant difference was found between curettage and enucleation and resection in terms of recurrence following a period of 2 years, during which time the lesion is most likely to recur.¹³

Patient’s perspective.

I was formally diagnosed with myxoma in my left mandible at the age of 26. Following a dental appointment in 2007, I was referred to a private maxillofacial specialist about the abnormal growth. The only way to get the tumour out was to go through the traditional radical surgical approach. As I sat in the surgeon’s office with a consent form in front of me, he diligently went through the risks and the outcomes following this procedure: lengthy recovery taking months, scars on my face and leg, completely numb lower left lip and lower left side of my face, drooping of the facial muscles and drooling for the rest of my life! Other concerns I voiced to him were how this will impact my professional consulting career and therefore my livelihood; the man I was about to marry will have a disfigured wife (while true love overcomes all obstacles, that was not the obstacle I was going to get over personally, and it would have impacted my mental health).

In the spirit of getting a second opinion, I had private consultations with two other surgeons. To my dismay, they recited exactly the same procedure, with exactly the same outcomes. Suddenly the world was crashing; I spent a few days locked up in the house, trying to figure out how to deal with this and will my life ever be normal.

By chance I was referred to another surgeon (fourth), who first and foremost considered the quality of my life and in fact my future. Professor Williamson explained to me he would try something new which would suit me and would not impact negatively on my quality of life as much as the traditional procedure. Following the new approach surgery, I was able to drink, talk, feel my lower left lip and walk within several hours. There was a very minimal adjusting period to the missing teeth. My physical recovery period was astoundingly short compared with what I was expecting with the original surgery. There were minimal lifestyle compromises I had to make during the recovery, and within a week I was back being myself.

I continued with my consulting career following the surgery; a few months later, I married the same man whose kisses I can feel on my lips and I became the marketing face of wedding photographer’s business with our wedding photo album. People do not look at my face and wonder/ask what happened, as I have no physical scars by which I need to feel defined or accepted (with the exception of the impact the first three consultations had on my mental well-being). I no longer feel sorry for myself or deprived, thinking how unfair life is (yes, it could be worse). This procedure allowed me to be myself as I was before the myxoma.

Learning points.

• Odontogenic myxomas are an exceedingly rare connective tissue benign growth originating in the tooth-bearing regions of the oral cavity.

• They grow in size over a long period of time and patients are often unaware of them until they are sufficiently large.

• The treatment for these lesions can be said to be on a spectrum from enucleation to radical resection: it is advisable to start treatment with the more conservative options and gradually use the more aggressive options only if there is a recurrence.