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This case report presents a 13-year-old girl who attended an orthodontic clinic for an ectopic UR5. After investigation, a diagnosis of an odontogenic myxoma was made and the tumour was excised. A panoramic radiograph taken almost two years earlier for another dental problem was found to show an ectopic UR5 associated with a subtle radiolucency.
Odontogenic myxomas may be of higher frequency than once thought in the paediatric population and therefore should always be considered in the differential diagnosis of any intraosseous radiolucency. Any radiolucent area associated with an unerupted tooth should be investigated further or closely followed up.
Clinical Relevance: The odontogenic myxoma is a rare but potentially serious benign tumour of the jaws.
Article
The odontogenic myxoma is a relatively rare, locally invasive, benign tumour of the jaws with its origin believed to be the mesenchyme of the developing tooth.1 It is slow growing and is characterized by mucoid and gelatinous grey-whitish tissue that replaces the cancellous bone and expands the cortex.
Approximately 2.2% of central odontogenic tumours are myxomas, the third most common after odontomas and ameloblastomas.2 The incidence is likely to be even greater in children, with Keszler et al finding myxomas accounting for 12.5% of odontogenic tumours in a sample of paediatric patients.3
Most studies have found females more commonly affected than males,1,2,4-6 with an age ranging from 3 months to 71 years.4,6 The mean age of presentation is generally the third or fourth decade2,4,6,7 and most tumours appear to be located in the lower jaw, in particular the posterior mandible.2,4–7
The most common clinical presentation appears to be swelling with bone expansion,6 with other features including bony perforation, pain, paraesthesia, mobility of the teeth and ulceration.4
Radiographically, the tumour is seen as a unilocular or multilocular radiolucent lesion with well-defined borders and fine bony traceculae. Multilocular lesions appear to be the most common.1,4-6 Root resorption can be a feature,1,4 however, tooth displacement is often more common.5,7 A biopsy is essential4,5 since some myxomas may lack these characteristic appearances7 and this can lead to an incorrect clinical diagnosis.3
Radical surgery, excision, and enucleation followed by curettage of the surrounding bony tissue have all been advocated as treatment options.4 Since the tumour is locally invasive, it is associated with a high re-occurrence rate and, therefore, long-term follow-up is advocated for a minimum of five years.8 Additionally, it has been suggested that cryotherapy to the tumour bed may reduce re-occurrence.9
This case report presents a 13-year-old girl who presented with an increasing mass over her cheek. A panoramic radiograph revealed a large radiolucency and an ectopic UR5. Subsequently, a biopsy confirmed the diagnosis of an odontogenic tumour in this region. The need to consider this rare but important condition in patients with ectopic teeth is highlighted.
Case report
A 13-year-old female had noticed a gradually increasing swelling around the right cheek. She was sufficiently concerned to visit her general dental practitioner, where a peri-apical radiograph was taken. This showed an ectopic UR5 surrounded by a large radiolucency. A referral to the orthodontic department was then made, where she was seen a few weeks later.
The patient reported that the swelling had been gradually increasing in size over the last four months and, although it had not been particularly painful, it was uncomfortable, especially when she was eating. Recently, she had also started to suffer with a congested nose.
Her medical history revealed that she had hay fever and had suffered with pneumonia secondary to bronchiolitis at around four months of age. Dentally, the patient had good oral hygiene; however, she had undergone a general anaesthetic just over two years ago for the extraction of a carious LL6. A panoramic radiograph, that had been taken at the time, showed an ectopic UR5 surrounded by a subtle radiolucency (Figure 1). No further investigations, follow-up or referral to an orthodontist was arranged for the ectopic tooth at that time.
Figure 1. Panoramic radiograph taken for carious permanent molars approximately two years before the patient presented with the odontogenic myxoma. Note the ectopic UR5 and associated radiolucency.
Orthodontically, she presented with a Class I incisor relationship on a moderate Skeletal II base with a normal lower face height. The molar relationship was Class I on the right side and Class II on the left and both arches were well aligned. The UR5 was unerupted and the URE was retained and firm (Figure 2).
Figure 2. The arches were generally aligned and the patient had a reasonable occlusion. All of the teeth, including the URE, were firm.
The extra-oral swelling was tender to palpate but appeared hard (Figure 3). Intra-orally, the swelling extended from the gingival margins to the deepest part of the buccal sulcus in the upper right quadrant (Figure 4).
Figure 3. The right cheek area was raised, hard and tender to palpate.Figure 4. The swelling extended from the gingival margins to the deepest part of the sulcus.
Radiographically, a large multilocular radiolucency was seen which measured almost 5 cm, extending virtually to the midline anteriorly and the third molar posteriorly. The UR5 had been displaced mesially and was positioned above the roots of the UR3 and 4. The roots of the UR4 and 6 had also been displaced but showed no obvious root resorption (Figure 5).
Figure 5. Panoramic radiograph taken at presentation of the swelling. The multilocular radiolucency measured almost 5 cm in diameter and had displaced the UR5. The roots of the UR4 and UR6 had also been displaced. Despite the expansion of the lesion, no root resorption is evident.
A CT scan of the facial bones (Figure 6) showed a large mass filling and expanding the right maxillary sinus with thinning of the bone at its margins, although in some places the bone had been completely eroded. This pattern suggested rapid growth of the tumour over recent months. Nasal involvement was seen, however, the pterygoid process and plates remained intact. The orbital floor was not involved but had been displaced. The material within the mass was of a lower attenuation than muscle but of a higher attenuation than simple cystic fluid.
Figure 6. CT of the facial bones shows the extent of the mass with thinning of the bones at the margins and displacement of the orbital floor.
The patient subsequently had an incisional biopsy which showed a poorly cellular myxoid lesion composed of bland spindle cells set in a myxoid stroma. There was no evidence of malignancy and a provisional diagnosis of an odontogenic myxoma was made.
Arch bars were constructed to stabilize the maxilla after the tumour had been enucleated. A unilateral osteotomy was performed to gain access to the tumour site. Eggshell bone was found over the buccal cortex. The orbital floor, ethmoid areas and posterior wall of the maxilla were all involved. The posterior wall, buccal and medial regions were treated with a liquid nitrogen probe. The roots of the UR4, UR6 and UR7 had also been associated with the tumour but were not sacrificed (Figure 7). The UR5, which had been displaced into the region of the lateral nose, was extracted (Figure 8a) and the arch bars were fitted for six weeks. The patient had an uneventful recovery and was discharged after a three night stay in hospital.
Figure 7. Intra-operative view after enucleation of the odontogenic myxoma. Involvement of the roots of the UR4 and UR6 is clearly seen.Figure 8.
(a) Extracted UR5. (b) Enucleated odontogenic tumour with its off-white colour. The tumour was gelatinous in texture.
The enucleated tumour (Figure 8b) was sent for examination and showed mature bone with an adjacent poorly cellular lesion consisting of spindle- and stellate-shaped cells in a fibrous and myxoid stroma. The diagnosis of an odontogenic myxoma was confirmed. A radiograph was taken one week after the enucleation and showed a uniform radiolucency in the region of the tumour (Figure 9). The UR4, 6 and 7 will require endodontic therapy and, owing to the high re-occurrence rate, an MRI scan is due to be undertaken six months after the initial surgery and subsequently on a yearly basis.
Figure 9. Post-operative panoramic radiograph with arch bar in place for stabilization. Note the roots of the UR4 and UR6 are now upright. These teeth were completely mobile and were therefore placed into more favourable positions.
Discussion
We presented a case of an odontogenic myxoma that was diagnosed and treated in a 13-year-old girl. Odontogenic myxomas have been considered rare in children with Noffke et al reviewing 30 cases and finding no affected individuals under the age of 10.5 Others, however, have found odontogenic tumours more frequent in children; 22% in a study of 41 odontogenic myxomas7 and 12.5% in a study of 80 odontogenic myxomas.3 Thus, one should consider odontogenic myxomas to be of higher frequency than once thought in the paediatric population.
This tumour had reached considerable size, measuring 5 cm in diameter on radiographic examination. Odontogenic tumours have been known to vary from 1 cm to 13 cm.6 However, these tumours tend to appear larger in children, often appearing greater than 4cm,3 particularly in the maxilla, where wide destruction of the maxillary bones can occur.
Odontogenic myxomas can show a range of radiographic appearances upon examination5 and authors have attempted to classify them.7 The lesion may appear as a unilocular or multilocular radiolucency, with either honeycomb, tennis racket or soap bubble patterning. Cortical expansion and tooth displacement can be seen. The lesion in this case was multilocular and presented with cortical expansion and tooth displacement.
A panoramic radiograph taken approximately two years prior to presentation with the odontogenic myxoma showed there to be an ectopically developing UR5. In hindsight, closer inspection of the area may have warranted further investigations or more attentive monitoring of the area. Neither was done in this case and, over the next two years, expansion of the lesion took place. There is a need to be vigilant of any ectopic teeth, particularly one associated with a radiolucency. While dentigerous cysts may be common, an odontogenic myxoma should always be considered in the differential diagnosis of an intraosseous radiolucency.
Treatment of odontogenic myxomas remains controversial. Complete surgical removal by conservative treatment can be difficult because, unlike most benign neoplasms, the myxoma is not encapsulated and its myxomatous tissue infiltrates the surrounding bony tissue without its immediate destruction. This probably explains the high rate of recurrence found after curettage or local surgical excision.1
The current recommended therapy depends on the size of the lesion and on its nature and behaviour and can vary from curettage to radical excision. The treatment protocol can resemble that of solid type ameloblastoma.8 A radical primary resection of the tumour, with maximal preservation of surrounding anatomic structures, is considered necessary (healthy anatomical borders of 0.5–1 cm beyond the tumour's radiographic borders).
There is an obvious reluctance to carry out a wide surgical excision (partial or hemi-maxillectomy) in children owing to concern about facial disfigurement and the interference with facial growth. The application of liquid nitrogen cryotherapy as an adjunct to traditional therapy of a myxoma in paediatric patients9 may be advantageous. Liquid nitrogen may limit recurrence because of it unique ability to devitalize the organic component of bone while leaving the inorganic framework intact. In this case, a liquid nitrogen probe was selectively used during the enucleation in order to maintain control of re-occurrence and reduce unnecessary tissue destruction.
Owing to the short follow-up of this case at present, we are not able to report on re-occurrence, although the patient will need very long-term follow-up.
Conclusion
This case reports presented a 13-year-old girl who attended an orthodontic clinic for an ectopic UR5. After investigation, a diagnosis of an odontogenic myxoma was made and the tumour was excised. A panoramic radiograph taken almost two years earlier for another dental problem was found to show an ectopic UR5 associated with a subtle radiolucency.
Odontogenic myxomas may be of higher frequency than once thought in the paediatric population and therefore should always be considered in the differential diagnosis of any intraosseous radiolucency. Any radiolucent area associated with an unerupted tooth should be investigated further or closely followed up.
