Conservative treatment of ameloblastoma in mandible: case report

Conservative treatment of ameloblastoma in mandible: case report

CAMILA LOPES GONÇALVES 1 | FELIPE EDUARDO BAIRES CAMPOS 1 | LUIZ FELIPE CARDOSO LEHMAN 1 | ROBERTA RAYRA MARTINS CHAVES 2 | FLÁVIA LEITE LIMA 1 | WAGNER HENRIQUES DE CASTRO 1

ABSTRACT

Ameloblastomas are slow-growing benign odontogenic tumors, locally invasive, that can reach varied proportions according to the time of evolution. The treatment of ameloblastomas has been controversial among surgeons. A patient with ameloblastoma in the mandible, treated by resection with conservative safety margin and of adjuvant therapies. After 4 years of follow-up without recurrence, the surgical defect reconstruction was performed by means of autogenous free graft from iliac crest and implant-supported dental prosthesis. After 9 years of follow up, the patient has no signs of recurrence and no esthetic and functional changes.

Keywords: Ameloblastoma. Mandibular reconstruction. Mouth rehabilitation. Conservative treatment.

1 Universidade Federal de Minas Gerais, Programa de Residência em Cirurgia e Traumatologia Bucomaxilofacial, Hospital das Clínicas (Belo Horizonte/MG, Brazil).

2 Universidade Federal de Minas Gerais, Programa de Mestrado em Estomatologia (Belo Horizonte/MG, Brazil).

How to cite: Gonçalves CL, Campos FEB, Lehman LFC, Chaves RRM, Lima FL, Castro WH. Conservative treatment of ameloblastoma in mandible: case report. J Braz Coll Oral Maxillofac Surg. 2019 Sept-Dec;5(3):45-50. DOI: https://doi.org/10.14436/2358-2782.5.3.045-050.oar

Submitted: 20/03/2018 - Revised and accepted: 03/09/2018

» The authors report no commercial, proprietary or financial interest in the products or companies described in this article.

» Patients displayed in this article previously approved the use of their facial and intraoral photographs.

Contact address: Camila Lopes Gonçalves Av. Marechal Mascarenhas de Moraes, 607, apto. 702, Centro – Vitória/ES CEP: 29.010-330 – E-mail: camila_clg@hotmail.com

INTRODUCTION

Ameloblastoma (AM) is a benign epithelial odontogenic tumor, locally invasive and presenting slow growth. Its most common site is the mandible, especially in body and ramus regions. The AM has no gender predilection and affects patients of different ages, with peak prevalence in the third and fourth decades of life, being uncommon in people under 19 years.¹ Generally, the AM presents clinically as a painless swelling, resulting from expansion or destruction of the jaws.¹ The proportion of facial asymmetry caused by the lesion is related to the period of neoplasm evolution.¹

On radiographic or tomographic examination, the AM usually exhibits a unilocular or multilocular osteolytic image, lined by a radiopaque or hyperdense halo, besides expansion of the cortical bone. There may be impacted teeth, displacement and/or resorption of dental roots associated with the tumor.²

The most common histopathological types of AMs are follicular and plexiform.² Other types as acanthomatous, granular cells, basal and desmoplastic cells, though rare, can also be observed. The histopathology of ameloblastoma consists basically of proliferation of epithelial cells that are arranged in varying patterns, which sometimes are present in the same tumor.

The treatment of AMs is controversial. Due to its aggressive behavior and high tendency to relapse, the classic treatment is tumor resection with a safety margin in normal tissues. However, more conservative therapeutic approaches - including enucleation,³ curettage,¹ marsupialization 4 or resection with smaller safety margins - have been proposed, particularly associated with supporting therapies as chemical cauterization (Carnoy’s solution), 5 peripheral ostectomy 1 cryotherapy (liquid nitrogen). 1,4

The aim of this paper is to discuss the possibility for conservative treatment of ameloblastoma, by presenting the case of a patient affected by the tumor in the jaw, treated by lesion resection with a minimal safety margin and oral rehabilitation, with bone graft and implant-supported dentures, who did not present signs of neoplasm relapse after 9-year follow-up. The patient signed an informed consent in accordance with Resolution N. 466 of the National Health Council, of December 12 2012, allowing publication of images in scientific journals.

CASE REPORT

A male patient, aged 22 years, attended the Oral and Maxillofacial Surgery and Traumatology Service of the Clinics Hospital at the Federal University of Minas Gerais for evaluation of asymptomatic lesion in the mandible. He reported no pain symptomatology, paresthesia, dysesthesia or hypoesthesia, and had no comorbidities. Extraoral and intraoral physical examination revealed no noticeable changes (Fig. 1A). However, the CT scan showed extensive hypodense image in the region of the symphysis and left mandibular body, multiloculated, with aspect of destruction and bone expansion, associated with teeth 31, 32, 33, 34, 35 and 41 (Fig 1B). An incisional biopsy confirmed the diagnosis of conventional AM (Fig 1C). By intraoral surgical access under general anesthesia, the tumor was removed using a minimal marginal resection of the mandible, with safety margin ranging between 5 and 10 mm, maintaining the lower border of the mandible, extracting the associated teeth and also tooth 42 (Fig 1D). Adjutant therapies as peripheral ostectomy over the entire lesion extent and application of Carnoy’s solution (3ml of chloroform, 6 ml of absolute ethanol, 1 ml of glacial acetic acid and 1 g of ferric chlorite) were performed for 5 minutes on the entire surgical field. After 4-year follow-up, with quarterly visits in the first year, at each semester in the second, and yearly from the third year, the clinical and imaging examinations should no lesion relapse. The patient was then submitted to a mandibular reconstruction procedure consisting of placing, by extraoral surgical access (submental), a free autogenous iliac crest bone graft, fixed with 2.0 System titanium plates (Fig 2). At five months after grafting, the region was rehabilitated by an implant-supported denture using four implants: three Cone Morse platform implant with 3.75 diameter and 13 mm mm length in the grafted area; and one implant in the position of molars, platform Cone Morse, with 5 mm diameter and 11 mm length (Fig 3A and 3B). After nine years of surgery for tumor resection, there were no signs of relapse and the patient was pleased with the treatment results (Fig 3B and 3C).

A

MENTUAL FORAMEN

B

C

D

Figure 1: A) Intraoral preoperative image, showing normal aspect. B) Computed tomography showing a hypodense image, well defined, multilocular, in the region of symphysis and left mandibular body. C) Lesion composed of nests and cords of odontogenic epithelial cells with solid growth pattern. Individually, the epithelial cells in the periphery were columnar, hyperchromatic, and arranged in palisade and similar to ameloblasts. In the central portion, cells presented loose arrangement similar to stellate reticulum of the enamel organ. Note cystic degeneration in focal areas. The stroma is fibrous and represented by vascularized connective tissue. D) Marginal resection of the mandible, with preservation of the base bone.

Figure 2: Surgical reconstruction of defect with free autogenous iliac crest bone graft, 4 years after tumor resection.

A

B

C

Figure 3: A) Intraoral aspect after rehabilitation with implants. B) CT scan showing implants placed and no relapse nine years after tumor resection. C) Axial mandibular section nine years after tumor resection, indicating no relapse.

DISCUSSION

In 2017, the classification of AMs was revised and simplified by the World Health Organization. These tumors were divided into ameloblastoma, unicystic ameloblastoma and extraosseous/peripheral ameloblastoma. The adjective “solid/multicystic” for conventional ameloblastoma was removed because it had no biological significance and could lead to confusion with the unicystic ameloblastoma. The desmoplastic ameloblastoma was reclassified as a histological subtype, and not as a clinical-pathological disorder. 6

The treatment of AMs varies between more radical forms – as tumor resection, together with a significant amount of normal tissue, used as safety margin – to more conservative approaches, which include enucleation, curettage, marsupialization (unicystic AM) and resection with a minimal safety margin. In this case, we chose a conservative approach, combined with supporting therapy, considering the anatomical location of the tumor, histological type, size, clinical aspects and patient’s expectations after being informed about the possible treatment options.

The literature reveals a 3.15 higher risk for relapse when AMs are treated conservatively. The relapse rate of AMs varies between 55 and 90% after conservative treatments and between 15 and 25% after more radical treatments 1 . However, we understand that, in selected cases of localized lesions of the mandible, which apparently respect the base cortical bone, the patient should be offered a more conservative treatment, keeping it under close and regular monitoring.

Considering the local aggressiveness and high propensity for relapse of AM, its classic treatment recommended in the literature is radical tumor resection with a safety margin. The safety margin is prescribed in different manners, according to several authors. Gortzak et al. 3 proposed a safety margin of 1 cm of apparently healthy bone, Gardner et al. 7 suggested a marginal resection with 1.5 cm of mandibular bone apparently not compromised by the tumor, and removal of soft tissue margin in cases of tumors with basal cortical expansion. Williams 8 proposed a resection with 2 cm of margin of normal bone and adequate margin of soft tissues free of tumor, as established by freezing biopsy. Other authors recommend bone margins even greater than 2 cm, for an appropriate resection. 9

In the case of AMs, more conservative treatment options should be considered, particularly when supporting therapies such as peripheral ostectomies, cryotherapy and chemical cauterization (Carnoy’s solution) can be provided. In this clinical case, the area of marginal mandibular resection was designed to involve all bone affected by the tumor, based on observation of a recent CT scan. The lateral limits of resection in alveolar bone ranged between 5 and 10 mm. However, it did not advance to the base bone beyond the tumor margins. Even though tooth 42 was not associated with the neoplasm, it was removed as a safety margin, even because its socket would be included in the peripheral ostectomy area. Peripheral ostectomy was performed around the surgical site, especially the mandibular base, after tumor removal. Finally, chemical cauterization was performed in the bone bed, using Carnoy’s solution for 5 minutes.

Scientific evidence suggests that some treatment protocols for AMs should be revised. 3 Authors who studied the growth pattern of large AMs in the mandible observed the presence of tumor cells in the bone marrow, at a maximum distance of 5 mm from the tumor mass. They also observed expansion and invasion of cortical bone by the lesion. The mucoperiosteal layer was affected, but not perforated, with the periosteum apparently acting as a kind of effective barrier against the tumor. There was no neoplasm in the inferior alveolar nerve and soft tissue above the periosteum. Finally, the present authors suggest a safety margin of 1 cm, observed from the tumor radiography. 3

Especially in cases of AMs, we understand that curative surgery is the priority in patient treatment. However, we must reflect on the functional, esthetic and psychological sequels that can result from a more aggressive treatment, and the high morbidity and complexity of reconstructive surgery.

Almeida et al. 1 , in a meta-analysis, found no statistically significant difference regarding the relapse rates between marginal bone resection with preservation of continuity and segmental resection of the jaw. These findings advocated the therapeutic option for this case. Therefore, during surgery, maintenance of the base portion of the mandible when it is not affected by the tumor is mandatory. Preservation of the mandibular line is essential to ensure the facial symmetry and facilitate dental rehabilitation.

The AM does not change its biological behavior and there is no scientific evidence that relapse complicates the treatment 1 . This tumor has strong affinity with bone and rarely migrates into the soft tissues, usually respecting the periosteum as a barrier. Because of its benign nature, some surgeons believe that the initial treatment of AM should always be conservative, with radical treatment being reserved for relapses. 1

Even when it occurs, relapse is initially small, discrete and localized, which facilitates further treatment when diagnosed early. 5

Thus, we emphasize that the postoperative follow-up of patients treated for AM is imperative and should be as long as possible, regardless of the treatment modality employed.

In the case of AMs in the maxilla, the resection with safety margin becomes the best indication for treatment because, in this bone, these tumors become dangerous and more difficult to treat due to the cancellous bone, proximity to the orbit, nasal fossa, pterygomaxillary and infratemporal spaces. Moreover, the relapse can escape between the ethmoid labyrinth and reappear at the cranial base. 1,5 Variations in treatment techniques of ameloblastomas are observed, for the best benefit for patients. Before decision making regarding the treatment of ameloblastoma, factors as clinical and histopathological presentation of the tumor, lesion size, anatomical site involved, patient’s age, rate and condition of expected relapse, and possible physical, functional and psychological impacts, should be considered by the surgeon. 10

It is clear that there are many variables in choosing the ideal treatment for AMs, which explains the great controversy on the subject in the literature. This case demonstrates that, when properly indicated, the conservative treatment combined with adjutant therapies, long-term follow-up and proper dental rehabilitation can assure the patient, in addition to curing the disease, a better quality of life after treatment.

FINAL CONSIDERATIONS

For the treatment of conventional ameloblastoma in the mandible, the surgeon should consider the accomplishment of a more conservative curative surgery, especially when supporting therapies may be employed. The patient’s cure with the lowest functional, esthetic and psychological disorder as possible should guide the therapeutic choice.

ACKNOWLEDGMENTS

We thank Professor Ricardo Alves Mesquita for his help in the case documentation.

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