Odontogenic Myxoma of the Maxilla: Diagnostic Considerations, Surgical Resection and Prosthetic Rehabilitation

Initial presentation

A fit and well 15-year-old female was referred to the OMFS department at York Hospital in April 2016 after attending her GDP for a routine examination. The GDP noticed an asymptomatic firm expansion of bone in the upper right quadrant along with a slightly displaced UR4. There was no evidence of erythema, ulceration or pus discharge (Figure 1).

Investigations

A panoramic radiograph taken in April 2016 (Figure 2) revealed a mixed radiolucent/radio-opaque area in the right maxilla extending from the distal aspect of the UR3 to the mesial aspect of the UR6, causing displacement of teeth. A cone beam computed tomography (CBCT) scan taken in July 2016 was more useful in exposing the dimensions of this lesion, along with a sparse and course trabecular pattern and patchy calcifications (Figure 3). Expansion of the buccal plate and right maxillary sinus encroachment could also be seen but no root resorption was evident.

Further examination under general anaesthesia (GA) in August 2016 revealed a soft tissue mass extending around the upper right premolars and a thick white jelly-like material invading into bone. A biopsy and histopathological analysis showed spindle-shaped cells with an eosinophilic cytoplasm embedded in loose myxoid matrix (Figure 4). A diagnosis of OM was reported in October 2016.

Surgical treatment and restorative rehabilitation

Surgical resection was performed under GA in January 2017. A buccal and palatal full mucoperiosteal flap was raised and UR3 and UR6 were extracted. A block resection with a safe margin was carried out using a piezoelectric saw along with an osteotome. This extended to a level below the infra-orbital foramen (Figure 5 a, b). The right buccal fat pad was used for immediate reconstruction and was sutured over the defect. The resection involved the antrum but oral mucosa closure was achieved and hence an obturator was not required.

An upper partial immediate denture was designed in collaboration between the restorative dentist and surgeon (Figure 6). This was constructed via impressions taken prior to the planned surgery.

An immediate Essix retainer was also constructed as a reserve option if necessary (Figure 6). This was constructed by bonding acrylic teeth to a clear vacuuform material. The immediate denture was of reasonable fit and required minimum adjustment (Figure 7).

Discussion

Features of OM vary and it should be considered in the differential diagnosis of both radiolucent and mixed radiolucent/radio-opaque lesions in both jaws for all age groups. Table 1 shows differential diagnoses in adults and children and it includes a wide variety of benign but also malignant tumours.² Clinical, radiographic and microscopic features are important in the diagnosis of head and neck lesions. Histology with immunohistochemical analysis is most reliable in distinguishing myxoma from malignant tumours.²

Early diagnosis is vital and it is imperative that, during routine follow-up, extra- and intra-oral examinations are thorough and systematic. Prior to the GDP referral, the patient received orthodontic treatment in secondary care. A panoramic radiograph was taken in July 2015 (Figure 8) and this lesion was missed. This highlights the importance of carefully examining and reporting radiographs along with continued education and training in line with Ionizing Radiation (Medical Exposure) Regulations 2000 (IRMER).⁹

Surgical management varies depending on the location, size of tumour, age of patient and individual experience.² This ranges from enucleation and the application of Carnoy's solution to surgical resection with a 0.5–2 cm margin and immediate microvascular free flap reconstruction.^2,3,4,7,8

Carnoy's solution penetrates cancellous spaces in bone and thus devitalizes and fixes remaining tumour cells. It is preferably not to be used in the vicinity of neural structures or the maxillary sinus to prevent neuropathy or necrosis of the sinus wall.¹⁰ Other complications include infection, dehiscence and bone sequestrum formation.¹¹ Carnoy's solution has also been reformulated without chloroform because of its association with cancer and reproductive toxicity.¹²

Unlike most neoplasms, the myxoma is not encapsulated and myxomatous tissue infiltrates adjacent bone without immediate destruction. This could explain why conservative approaches, such as curettage or simple local excision, have a reported recurrence of approximately 10% to 33%.^4,7 Despite aggressive local growth, OMs are not believed to undergo malignant transformation or metastasize.¹³

This patient was initially seen in the department within two weeks after the GDP referral, which is in line with National Institute for Health and Care Excellence (NICE) suspected cancer guidelines.¹⁴ The benign tumour was resected approximately nine months afterwards. This needs to be reviewed as the Department of Health states that patients have a right to start consultant-led treatment within a maximum of 18 weeks.¹⁵

Patients facing loss of their teeth and associated structures may experience apprehension towards losing their social image or daily function.¹⁶ The restorative dentist's role is to provide functional and aesthetic restorations for a smooth transition. A cobalt chrome partial denture can be provided once healing is complete, for increased comfort and retention whilst monitoring for any recurrence. In the case of a paediatric patient, several appliances could be provided until growth is complete prior to bone augmentation and implant rehabilitation.

A minimum of 5 year follow-up is advised prior to moving onto the final reconstructive phase,⁷ with the first 2 years being the period when the neoplasm is most likely to recur.⁴ Annual panoramic radiographs for all lesions are advocated (Figure 9). CBCT imaging is more reliable for maxillary lesions.⁸