Abstract
Odontogenic myxoma (OM) is a rare tumour arising in the jaws. The tumour is purported to be odontogenic in origin due to the frequent localisation of the tumour inside the jaws in close relation to teeth. The aim of this report was to detail the course of a patient who developed OM of the maxilla, underwent adequate ablative surgery and reconstruction, including tooth transplantation to the original tumour site, and subsequently developed a local recurrence in close proximity to the teeth transplanted to the reconstructed maxilla 6 years after the first diagnosis. Once again, a partial maxillary resection was performed, with no reconstruction. The patient has been free from tumour recurrence for over 20 years. We discuss the current hypothesis on OM pathogenesis and the possible impact of actively dividing cells on tumour re-growth.
Odontogenic myxoma (OM) is a benign neoplastic lesion of the jaws, arising predominantly in tooth-bearing areas (1-4). Extra-osseous myxoma of the facial region is very rare (5). However, myxoma is a well-known entity in other regions of the body, even without any apparent association with hard tissues (5-7). The association of OM with fibrous dysplasia has been repeatedly excluded (8, 9). The cellular origin of OM is still a subject of investigation (1, 2). Macroscopically, the tumour is firm or of a gelatinous consistency and, after surgical exposure, can eventually be drawn into threads (1-4). Microscopically, the tumour is composed of mesenchymal cells, that are believed to be of odontogenic origin, embedded in a collagen-rich matrix (1). A repeated argument put forward in favour of the odontogenic origin of OM tumour cells is the preferential location of OM in dentoalveolar regions (1-4). Several authors emphasised the similarities in the microscopic texture between tumour and dental pulp, and speculated that scattered cells of the dental pulp or periodontium may give rise to OM (1-3). OM is a rare lesion. The relative frequency of OM in relation to other odontogenic tumours varies considerably. OM constitutes about 5% to more than 20% of odontogenic tumours, but these variations likely represent variations of allocations to specialised medical centres rather than well-justified epidemiological data (10-14).
Radiographic analysis is essential in the diagnosis of odontogenic tumours (1-3, 15-26). OM exhibits a highly variable radiomorphology (15-26). Some radiographic findings in cases of OM are multilocular areas of radiolucency resembling a “honeycomb” and “soap-bubble” appearance of osteolysis (1-4), but these findings are not characteristic of OM (15-26). Interestingly, unilocular lesions are found as frequently as multilocular osteolysis in OM (15) or may even be the predominant feature in children with OM (18).
Therapy of OM is radical resection with safety margins (27, 28). Thus, ablative surgery for OM may result in severe impairment of oral functions, requiring anatomical reconstruction. Reconstructive surgery intends to restore the shape and volume of the affected jaw region, including prosthetic rehabilitation (27, 28). In young patients, transplantation of developing teeth is an option for rehabilitation to an almost physiological condition (29). Close follow-up is recommended to allow early surgery in cases of tumour relapse (1-3).
Case Report
A 12-year-old girl was admitted to the Department of Oral and Craniomaxillofacial Surgery for the diagnosis and treatment of an OM of the right maxilla. Three weeks earlier, the patient had been surgically treated by a resident oral and maxillofacial surgeon for removal of a retained upper second premolar of the right side of the maxilla that had been incidentally diagnosed by an orthodontist on a radiograph performed during monitoring of orthodontic treatment (Figures 1 and 2). The referring surgeon reported to have planned the removal of an odontogenic cyst as assumed on the basis of x-ray images but intraoperatively, surprisingly, found a solid tumour surrounded by soft bone, which was sliceable with a scalpel. He had removed the second premolar from the sinus and adjacent soft and hard tissues. Initially, the histological diagnosis was a fibrous dysplasia but careful re-evaluation of the specimen revealed myxomatous stroma and the diagnosis was changed to OM, which was also revealed in the resection margins.
A: Orthopantomogram of the patient at the age of 10 years. The radiograph depicts a mixed dentition in accordance with age. Mesial to the permanent upper right first molar, the pericoronal radiotranslucency of the upper second premolar is reinforced, in particular in comparison to the developing second premolar of the contralateral side. Both predecessors are in place, but the root resorption of the right upper deciduous molar appears to be more advanced. B: Cropped image of lateral cephalogram disclosing a radiolucent maxillary sinus.
A: Detail of orthopantomogram of the same patient at the age of 12 years. The deciduous molar is still in place, but the successor is displaced cranially (arrow). The alveolar process apical to the deciduous molar shows a spongious radiopacity only in its distal part; the mesial apical region is radiotranslucent and the root of the first premolar is displaced. The transversal tomogram reveals the extensive dislocation of the tooth to the medial wall of sinus (B) and the sagittal tomogram visualises the loss of the developing tooth from bony contact (C).
On admission, the child exhibited an intact integument, a slight swelling of the right cheek, no erythema, and reported no painful sensation in the affected region. Opening of the mouth was not impaired. Oral inspection revealed a discrete increase in volume of the firm soft tissues covering the right maxillary process.
A partial resection of the maxilla was planned in order to remove the tumour. After circumcision of the vestibular mucosa in the premolar region, the mucosa was elevated and the affected bone exposed. The bone destruction had already included the alveolar process of adjacent teeth 14 and 16. The tumour of a cyst-like shape had compressed the maxillary sinus cranially to a small slit and destroyed the right anterior wall of the sinus. The tumour was easily detached from the osseous boundaries. The roof of the maxillary sinus, the lower ethmoid and the palatine bone appeared to be unaffected. The partial maxillectomy performed included teeth 14 and 16, lateral and medial walls of the maxillary sinus, and adjacent parts of the palate and inferior ethmoid. Biopsies were taken from all adjacent bones and the surfaces were carefully removed with a burr. Temporary restoration of the maxillary wall was achieved with individually contoured PDS film and the coverage of the defect was achieved by primary intention (Figure 3A and B). Histologically, the resection specimen revealed further parts of the OM and tumour-free resection margins.
Cropped images from orthopantomograms: immediately after resection (A), 3 years after ablative surgery (B), after bone augmentation (C) and after tooth transplantation (D).
Healing was uneventful and the patient developed no local recurrence during the subsequent observation period of 3 years. At that time, the developmental stage of the wisdom teeth of the 15-year-old patient allowed the planning of auto-transplantation of the right and left upper third molars to the former region of the first molar and second premolar. As a first step, iliac crest autografts were transplanted to the right side of the maxilla (Figure 3C). Biopsies of the implantation site excluded recurrence of OM and revealed scar tissue. Two months later, the tooth transplantations were successfully performed (Figure 3D), followed by orthodontic treatment, resulting in full restoration of the masticatory function and oral aesthetics (Figure 4). Biopsies of the former tumour region had excluded local tumour recurrence at the time of transplantation.
Three years later, the patient returned to our outpatient clinic because she had consulted her resident, who had performed an endoscopic biopsy of the right maxillary sinus, revealing local tumour recurrence (Figure 5A and B). Computed tomograms of the maxillary sinus supported the suspicion of osseous invasion of the ventro-medial site of the maxilla, in particular in the region of the transplanted teeth. A Le-Fort-I osteotomy was chosen to access the tumour from all sides (Figure 5C). The lateral maxilla was completely resected, including transplanted bone and teeth, orbital floor and also adjacent parts of the zygomatic bone. The defect was immediately reconstructed with iliac bone. Healing was uneventful. Histological investigation of the resection specimen revealed further parts of OM surrounding the transplanted teeth and the upper second molar. The resection edges were free of tumour. The patient declined further surgical measures to restore the bone and dentition. She was treated with a partial denture. The patient was followed-up over a period of 20 years and has developed no further tumour recurrence.
Discussion
This case report illustrates the unpredictable behaviour of OM of the jaws in the specific situation of tooth transplantation to the site of former tumour origin.
OM is a rare diagnosis with respect to the entire spectrum of differential diagnosis for osteolytic jaw lesions (1-3). Ranking of OM shows geographic variation, with it appearing to be less frequent in the Far East (13, 16) than in African or Caucasian populations (1, 11, 14). Radical surgery is recommended as the therapy of choice (1-4), but this attitude towards therapeutic strategies has been called into question (30).
Photographs of staged oral reconstruction. A: Lateral oral photograph of the deficient alveolar process of the right maxilla. B: Occlusal view of the defect state of the maxillary right molar region. C: Image of the dentition after bone augmentation and tooth transplantation. D: Extracted upper wisdom teeth prior to insertion into maxilla. E: Lateral oral image of the right side of the maxilla after completion of orthodontic tooth movement. F: Occlusal view of the transplanted teeth during tooth movement. Note all figure parts except D were made with a mirror placed in the oral cavity, therefore the images appear to show the contralateral side.
A: Cropped image from oral radiograph depicting an osteolytic lesion apical to the transplanted tooth that is situated mesial to the second molar. B: Detail of midfacial radiograph showing the loss of the right lateral sinus wall and complete radiopacity of the sinus region. C: Postoperative midfacial radiograph depicting radiotranslucent maxillary sinuses after midfacial surgery and miniplates in appropriate positions.
OM is a mimicker on conventional radiographs (17). Osteolytic lesions surrounding transplanted teeth are suspicious for an inflammatory process. However, OM can mimic such inflammatory findings (17). Surgical exploration and histological diagnosis of specimens from new osteolytic lesions following ablative surgery are mandatory in order to provide a correct diagnosis (3).
Anecdotal evidence was provided for the association of OM with sporadic oral malignancy (31), with tumour-suppressor syndromes (32, 33), and with simultaneously developing fibrous dysplasia (6), but this relationship appears to be coincidental and was excluded in the present case. The differential diagnosis of fibrous dysplasia and OM should pose no problems (9).
In the present case, the transplantation of teeth resulted in a late failure of oral rehabilitation and required extensive ablative surgery for local tumour recurrence. At first glance, the clinical course of this patient favours avoiding tooth transplantation to a region where an OM was previously resected. However, surgical standards were maintained during all phases of surgical therapy. Teeth were transplanted into a region with microscopically proven resection edges that were free of tumour (34). This result was again obtained years after excision of the primary tumour during preparation of the recipient site for bone augmentation and the further transplantation of teeth. Nevertheless, a local recurrence of OM occurred 6 years after tumour resection, 3 years after reconstructive measures. The teeth were harvested from jaw regions with normal radiological and clinical findings concerning both the donor sites of bone and the transplanted and incompletely developed molars. Multiplicity and metachronous development of several OMs in the jaws of the same individual is presently not known. It is unlikely in this case that the tooth buds had undergone a tumorous transformation. Nevertheless, the proliferative ability of these cells is probably higher than that of the surrounding teeth with fully developed roots (35-37).
Conclusion
OM should be considered in the differential diagnosis of jaw lesions in children and adolescents (22). In fact, OM is a tumour of the first decades of life (1). OM appears to be associated with unerupted teeth in only 5% of cases (22). However, obvious asymmetries in tooth emergence of synergetic teeth, and in particular tooth buds shifted far away from their expected development, should alert the clinician to perform advanced diagnostics, including surgical exploration of the region (38, 39). Tooth transplantation to jaw regions formerly affected by OM should be followed-up carefully.
Acknowledgements
Expert pathological diagnosis was provided by the late Professor Karl Donath, formerly head of the Department of Oral Pathology, Institute of Pathology, Eppendorf University Hospital.
- Received March 18, 2016.
- Revision received April 23, 2016.
- Accepted April 26, 2016.
- Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved
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