SURGICAL ONCOLOGY ANZJSurg.com
Mandibular ameloblastoma: clinical experience and literature review
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Eric Sham,* James Leong,* Rory Maher,* Michael Schenberg,† Michael Leung* and Alan K. Mansour† Departments of *Plastic and Reconstructive Surgery †Oral and Maxillofacial Surgery, Southern Health, Melbourne, Victoria, Australia
Key words ameloblastoma, mandibular neoplasm, reconstructive surgical procedure, surgical flap, bone transplantation. Abbreviations CT, computed tomography; OPG, orthopantomogram. Correspondence Eric Sham, Department of Plastic and Reconstructive Surgery, Dandenong Hospital, David Street, Dandenong, Vic. 3175, Australia. Email:
[email protected] E. Sham MBBS; J. Leong FRACS; R. Maher MBBS; M. Schenberg FRACDS(OMS); M. Leung FRACS; A. K. Mansour FRACDS(OMS). Accepted for publication 18 September 2008. doi: 10.1111/j.1445-2197.2009.05061.x
Abstract Background: Ameloblastoma is a locally aggressive odontogenic tumour of the mandible and maxilla that, if neglected, can cause severe facial disfigurement and functional impairment. A thorough understanding of its clinicopathological behaviour is essential to avoid recurrence associated with inadequately treated disease. Currently, wide resection and immediate reconstruction is the treatment of choice in most cases of mandibular ameloblastoma. We present our experience in the management of this disease and review the current status of the literature. Method: Retrospective review of all patients between 1996 and 2006 with histologically confirmed ameloblastoma. A literature review on the current understanding of this disease and its management is then presented. Results: Six patients were identified, ranging between 23 and 54 years old. All were females. Two tumours involved the angle and posterior body of the mandible, one the angle and ramus, one the body and two the anterior mandibular. Four patients underwent mandibular reconstruction with free tissue transfer and two by non-vascularized bone grafts. All procedures were successful. One patient developed deep vein thrombosis requiring anticoagulation. Another developed a collection at the mandibular surgical site requiring drainage. Satisfactory union was achieved in all cases with no evidence of recurrence. All patients had adequate cosmesis, masticatory efforts and speech. Conclusion: Management of ameloblastoma remains a challenge and requires a thorough understanding of the behaviour of its different clinicopathological variants. We have found segmental mandibulectomy and immediate reconstruction to be an excellent treatment option in our series of patients.
Introduction Ameloblastoma is an uncommon odontogenic tumour of the mandible and maxilla. It is a locally aggressive tumour that, if neglected, can reach an enormous size and cause severe facial disfigurement and functional impairment. It occurs with equal frequency in both sexes and has its peak incidence in the third to fourth decade of life.1,2 The disease is most often found in the posterior body and angle of the mandible but can occur anywhere in the mandible or maxilla.2 Overall, 80% of all ameloblastomas occur in the mandible and 20% in the maxilla.2,3 Clinically, ameloblastomas may be relatively asymptomatic and can be detected incidentally on radiological imaging. When symptoms are present, patients often complain of a slow-growing, painless swelling.2 Less commonly, they may present with © 2009 The Authors Journal compilation © 2009 Royal Australasian College of Surgeons
pain or paraesthesia (impingement on adjacent sensory nerves such as the inferior alveolar nerve), loose teeth, or malocclusion. Facial deformity, if present, may range from very mild to severe in delayed presentations. They may also be associated with the presence of unerupted teeth, in particular the mandibular third molar.1,4 Radiological investigations provide a useful aid to diagnosis. However, these findings are not pathognomonic and must therefore be confirmed with histological examination. The orthopantomogram (OPG) is a useful first-line investigation and may reveal lucency in the bone of varying size and shape associated with scalloped margins and resorption of the roots of involved teeth. Occasionally it can be a well-demarcated unilocular lesion, whereas often it presents as multiloculated expansile lucencies with a so-called ‘soap bubble’ appearance.5,6 Computed tomography (CT) may be useful in the
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assessment of the extent of the tumour, cortical destruction and extension into the neighbouring soft tissues.7,8 Histologically, ameloblastoma resemble enamel organs with no evidence of induction of hard dental tissues. They consist of nests, strands and cords of epithelial cells separated by small amounts of connective tissue stroma. Two predominant histological patterns exist: follicular and plexiform. Other variants include acanthomatous, desmoplastic, basaloid and papilliferous forms.2,9 In follicular ameloblastoma, the tumour cells are arranged in discrete nests with tall columnar cells containing nuclei of reversed polarity (oriented away from the basement membrane) palisading about the periphery of the tumour nests. The central core consists of loosely arranged cells that resemble the stellate reticulum of the enamel organ. The cells in plexiform ameloblastoma are basaloid or cuboid in nature and are closely apposed in anastomosing strands and cords with little evidence of stellate reticulum-like areas.2,10 Management of ameloblastoma poses a challenge for all involved in the field of head and neck surgery. Successful treatment requires not only adequate resection of the tumour but also a functional and aesthetically acceptable reconstruction of the residual defect. The roles played by all members of the multidisciplinary team including surgeons, nurses, dentists, speech pathologists, dieticians and physiotherapists are therefore essential. Numerous operative procedures including enucleation, curettage, marsupialization and radical resection have been described in the management of ameloblastoma.11 However, the pathological behaviour of this disease varies and high rates of recurrence are seen in inadequately treated disease. Wide resection and immediate reconstruction is currently accepted as the treatment of choice in most cases.12 With modern advances in reconstructive techniques, focus is being placed more and more on early functional recovery. In this study we review our experience in the management of mandibular ameloblastoma and the current understanding of this disease.
Method Patients who had histologically proven mandibular ameloblastoma between 1996 and 2006 were identified from the database of the anatomical pathology department. A review of all medical records, radiological images, operative reports and pathology reports was undertaken. A literature review on the current understanding of ameloblastomas and its management is then presented. All patients had preoperative radiological investigations including an OPG and a CT of the mandible. For those who underwent
mandibular reconstruction with the free fibular flap, lower limb angiography was also performed. Stereolithographic models of the mandible produced from high-resolution CT scans were manufactured in three cases to aid in operative planning and allowed for pre-adaptation of reconstruction plates. Two operative teams were involved in all procedures where reconstruction was achieved with microsurgical free tissue transfer. In these cases tumour resection was carried out by oral and maxillofacial surgeons with reconstruction performed by the plastic and reconstructive unit occurring in a staggered fashion. Three of six resections were carried out via a split-chin approach with the rest performed intra-orally. Radiological resection margins were ascertained intra-operatively with plain x-rays of the resected surgical specimen. Reconstructions of the mandibular defects were achieved with either non-vascularized iliac crest bone grafts or by microsurgical free tissue transfer with the free fibula flap or the deep circumflex iliac artery flap. The free fibula flaps were raised in the standard fashion as described in the literature.13 Contouring of the fibula was performed via one or two bicortical osteotomies with preservation of the continuity of the periosteum at one cortex and fixation achieved with either preoperatively or intra-operatively adapted plates. A skin paddle was used to reconstruct any mucosal defects as well as to aid in post-operative flap monitoring. All donor sites were closed by a combination of primary closure and split thickness skin grafting and the limb placed in a plaster splint. The deep circumflex iliac artery flap was raised in the standard fashion with the donor site closed primarily. After contouring, this flap was inset and fixation similarly achieved with reconstruction plates. A nasogastric tube was inserted intra-operatively in all cases to facilitate early post-operative enteral feeding and to avoid potential contamination of the healing oral wounds. All patients had a post-operative OPG for baseline monitoring as well as to evaluate the reconstructive effort. The multidisciplinary team involved in preoperative and post-operative care and rehabilitation included surgical, nursing, physiotherapy, speech pathology, dietetic and dental staff. All patients were followed up with interval imaging to assess for recurrence.
Results Patient data and results are summarized in Tables 1 and 2. Six patients were identified from the database as having histologically confirmed ameloblastoma. Age ranged between 23 and 54 years old
Table 1 Patient data Patient 1 2 3 4 5 6
Age (years)
Sex
Symptoms
Site
44 44 28 54 26 23
Female Female Female Female Female Female
Swelling Swelling Swelling Pain Swelling Incidental
Anterior mandible Left posterior body and angle of mandible Right mandibular angle and ramus Right anterior mandible Right posterior body and angle of mandible Left body of mandible
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Table 2 Operative data and results Patient
1 2 3 4 5 6
Defect (centimetres)
Reconstruction
Operative time (h)
Complications
Follow-up (months)
6.5 7 Right mandibular condyle to right angle – 6 Right angle to anterior margin – 5 6.5 5.0 4.5
Free fibula flap Free fibula flap Deep circumflex iliac artery osteocutaneous flap Free fibula flap Iliac crest bone graft Iliac crest bone graft
10 (6) 9 (4) 14 (8)
Nil Collection at mandibular site Nil
12 18 24
10 (6) 4 4
DVT Nil Nil
32 54 72
Bracketed figure under operative time column indicates the time of the reconstructive phase while the number outside the bracket indicates the total operative time.
Fig. 1. Patient 1 – 44-year-old female with swelling in the region of the anterior mandible. Preoperative orthopantomogram revealed multilocular lucencies in the region of the anterior mandible.
Fig. 3. Patient 1 – post-operative orthopantomogram showing the position of the free fibula flap with fixation achieved using a mandibular reconstruction plate.
Fig. 2. Patient 3 – 28-year-old female with multicystic ameloblastoma involving the right posterior body, angle and ramus of the mandible. Preoperative orthopantomogram.
(mean 36.5 years). All six patients were females. The most common symptom found in our patient group was painless swelling. Two tumours involved the angle and posterior body of the mandible. Two involved the anterior mandible (Fig. 1). One patient had involvement of the angle and ramus of the mandible (Fig. 2) with the other involving the body only. The size of the post-resection mandibular defects ranged from 4.5 to 7 cm in simple linear defects. In one case (Patient 3) the resultant defect was more complex, measuring 6 cm from the condyle to the ipsilateral angle then 5 cm from this point to the anterior resection margin at the body of the mandible on the ipsilateral side. Four of six patients underwent mandibular reconstruction with microsurgical free tissue transfer. The two smaller (
