25 September 2024: Articles
Multidisciplinary Approach to Mandibular Ameloblastoma: A Case Report on Surgical and Prosthetic Management
Unknown etiology, Challenging differential diagnosis, Diagnostic / therapeutic accidents, Management of emergency care, Clinical situation which can not be reproduced for ethical reasons
Fouad Al Omari1AEF*, Reem Mohammed Hakami
DOI: 10.12659/AJCR.944651
Am J Case Rep 2024; 25:e944651
Abstract
BACKGROUND: Ameloblastoma is a locally aggressive, benign, odontogenic tumor. Reports suggest that the chances of recurrence of this tumor are high if treated with a conservative approach. Concordantly, surgical removal of the lesion along with the affected adjacent tissues and bone structure is recommended to reduce the chances of recurrence. Post-surgical prosthetic rehabilitation is advised to improve speech, mastication, and aesthetic appearance. This case report highlights the treatment and reconstruction challenges that maxillofacial surgeons and their teams face in managing cases of large ameloblastoma.
CASE REPORT: A 41-year-old Sudani man was referred for the management of a large ameloblastoma associated with the left border of the mandible. Management consisted of surgical removal of the affected mandible along with prosthetically preserving the mandible with grafts and screws. Histopathological, computed tomography, and incisional biopsy evaluation confirmed the presence of ameloblastoma. Postoperatively, no complications were reported. Six months postoperatively, no sign of recurrence was seen. The patient was referred to a surgeon for placement of an endosseous implant.
CONCLUSIONS: When dealing with large ameloblastoma, an interdisciplinary dental team is essential for improving the treatment results. This case highlights the importance of precise and timely primary care diagnosis and a collaborative approach to treatment. By embracing advancements in digital technologies, surgeons can enhance functional and aesthetic results, improving long-term quality of life.
Keywords: Ameloblastoma, Mandibular Osteotomy, mandibular reconstruction, Surgery, Plastic
Introdcution
Ameloblastoma is a progressive, intraosseous, benign tumor of odontogenic origin with a tendency to recur [1]. It is usually a painless, progressive lesion, leading to expansion and destruction of surrounding bones and tissues. Most of these tumors are of benign origin, with a worldwide incidence rate of 0.7 cases per million person-years annually [2]. These tumors constitute 1–3% of odontogenic cysts and tumors of the maxilla and mandible. They most commonly occur during the third to fifth decades of life, affecting both the sexes equally [3]. The relative frequency of this tumor in the mandible is around 80%, while in the maxilla, it accounts for 20% of cases. Most cases of ameloblastoma in the mandible are seen in the ramus or body of the mandible [4].
According to clinical, radiographic, and histological findings, these tumors are characterized as unicystic, multicystic, adenoid, peripheral, and metastasizing forms [5]. Radiographically, this tumor is challenging to identify in the initial stages, and when growth is detected, it manifests as either unilocular or multilocular [6]. Histologically, ameloblastomas are classified into 4 patterns: solid multicystic, desmoplastic, unicystic, and peripheral. The unicystic pattern is further subdivided into 3 types based on mural development. Multicystic ameloblastoma and the mural unicystic ameloblastoma are considered the most aggressive tumors, with high risk of recurrence [7,8]. The treatment of this tumor depends on histological findings, and a conservative approach is often necessary for lesion removal, although this approach is seldom recommended [9,10].
Evidence in the literature suggests that before planning the management of ameloblastoma, a thorough examination of the mandible and maxilla should be conducted [9,10]. Treating large ameloblastomas presents a challenge in achieving complete excision and subsequent reconstruction of the mandible and/or maxilla [11–14]. Treatment typically involves enucleation, curettage, and surgical excision, depending on the size and origin of the lesion. The recurrence rates for en bloc resection and conservative management are 18.2% and 35.2%, respectively [15,16]. Wide removal of the lesion with a safety margin of healthy bone is recommended to reduce recurrence rates.
The current case report offers comprehensive insights into different treatment modalities and their outcomes for managing multicystic ameloblastoma while presenting a specific mandibular ameloblastoma case.
Case Report
INVESTIGATIONS AND FINDINGS:
The case details were explained to the patient, and informed consent was obtained. Radiographical, computed tomography and histopathological examinations were planned. An incisional biopsy was performed, and the specimen was stored in formalin. This specimen was further sent to the laboratory for histopathological investigation. Routine hematological examinations were done, and the reports were insignificant.
COMPUTED TOMOGRAPHY:
Axial CT (Figure 2) revealed a large, well-defined, multilocular, radiolucent swelling (7×10 cm) on the left body and the mandible’s ramus, causing the mandible’s expansion. However, no involvement of the inferior alveolar nerve was reported.
HISTOPATHOLOGICAL FINDINGS:
The histopathological findings of the specimen revealed islands of prolific odontogenic epithelium within fibrous connective tissue, characterized by classical peripheral palisading and stellate reticulum of the enamel organ (Figure 3A). A layer of tall, columnar, ameloblast cells was observed around the central area, with their nuclei positioned opposite to the basement membrane and microcysts formed; there was plexiform pattern distribution with anastomosing cords with cystic degeneration in a lax stroma (Figure 3B). Additionally, squamous metaplasia was noted, and the lesion extended into the soft tissue, although there was no infiltration of the periosteum into the bone trabeculae (Figure 3C). No lymphovascular or perineural invasion was reported. These findings strongly suggested the diagnosis of multicystic follicular ameloblastoma.
SURGICAL APPROACH:
Due to the extension of the lesion and to achieve an adequate margin, hemi-mandibulectomy was planned. Segmental resection of the mandible for removal of ameloblastoma and custom reconstruction of the mandible was performed under general anesthesia with precise incision (Figure 4). A left modified, pre-auricular, intraoral incision, and submandibular extension, along with left zygomatic osteotomy, was performed to gain access to the infratemporal fossa and mandible. An attempt was made to protect the facial nerve.
Resection of the left mandible from parasymphais to the temporal fossa with 1 cm of bony margin and soft tissues surrounding muscles like masseter, pterygoid, mylohyoid, and temporalis was performed. The lingual and facial nerves were persevered. A small portion of the skin was removed to maintain the patient’s facial aesthetic. The reconstruction plates (2.4-cm) were placed and secured with screws (Figure 5). During the complete surgical procedure, irrigation was done using a benzoyl peroxide solution. The surgical specimen consisted of a mandible segment, the lesion, and associated teeth (Figure 6). The wound was closed with the vicryl deep suture and monocryl subcutaneous sutures (Figure 7). No intra-operative complications were reported.
The patient’s postoperative recovery was uneventful, and he was discharged on the second day after surgery. He was prescribed cephazolin (0.5–1 g IV q6-8 h) and metronidazole for 2 days. At discharge, the patient was shifted to Azithromycin for the next 5 days. He was instructed to follow the diet protocol and was on a soft diet until recovery. He was instructed to improve the diet as tolerated. Instructions on the maintenance of oral hygiene were given. Figure 8 shows the mandible’s postoperative imaging, demonstrating the prosthesis’s placement.
Two weeks postoperatively, the patient returned to remove the sutures. During this visit, weakness was noted in the facial nerve’s left mandibular branch and the restriction of mouth opening. He was advised to continue the soft diet for the next 2 weeks and to improve his diet as tolerated. Three months later, a CT scan showed good prosthesis positioning, and no evidence of recurrence was seen (Figure 9). The 6-month postoperative photograph (Figure 10A) radiograph (Figure 10B) showed no sign of recurrence, and the patient was sent for prosthetic rehabilitation.
Discussion
Ameloblastoma are locally aggressive odontogenic tumors that can metastasize. Etiological factors associated with this tumor have evolved over the years and are still not established. The development of odontogenic tumors, such as ameloblastoma, is linked to remnants of the migrating epithelium at the cervical loop of the enamel organ [5]. It is well-established that ameloblastoma originates from the enamel organ, remnants of odontogenic epithelium, and the lining of odontogenic cysts [5]. Research suggests that the absence of the stratum intermedium impedes the differentiation of pre-ameloblasts into ameloblasts, as the stratum intermedium produces alkaline phosphatase, an enzyme crucial for breaking down nutritional elements necessary for ameloblast function during the bell stage [7,8]. Furthermore, the stellate reticulum within the tumor nests of columnar epithelium can degenerate, leading to formation of microscopic cysts. The coalescence of these microcysts results in the characteristic multicystic appearance of ameloblastoma [7].
Ameloblastoma can occur in both the sexes, but the incidence has been reported to be higher in females. Our patient had ameloblastoma in the posterior region of the mandible. Studies have reported that the mandible is the most common site associated with this lesion. However, in the studies by Chukweneke et al [17] and Adekeye et al [18], the anterior region was reported to be most involved. These differences among various populations are still unknown. Studies have related these differences with histological and molecular characteristics of tumors among various ethnic groups. In the study by Verma et al, 38.9% of patients with mandibular ameloblastoma presented with swelling, 13.5% had paresthesia of the mandibular nerve, and 11% had altered occlusion [19]. The present reported case had altered occlusion and mandibular nerve paresthesia.
Managing large mandibular ameloblastoma is a complex procedure requiring precision to save adjacent structures. The 2 most common approaches in treating ameloblastoma are conservative and radical management [13,14]. These procedures involve enucleation, peripheral ostectomy, cryotherapy, curettage, and chemical cauterization. While these methods are easy to perform and lead to fewer surgical complications, there is still a significant risk of recurrence, potentially resulting in further surgical intervention [13,14]. An effective approach to treatment involves either partial or complete removal of affected sites, with the treatment option of reconstructing both the hard and soft tissues immediately, at a later stage, or not at all. Achieving a long-term surgical result is achieved by removing all radiographic tumor boundaries and the involved overlying soft tissue, with margins extending 1.0 to 1.5 cm beyond the initial small lesions. The need for this extensive margin is based on previous research findings that showed the histologic margin of conventional ameloblastomas extends beyond the evaluated radiographic boundary by a range of 0.2 to 0.8 cm [20–22]. A substantial amount of data clearly shows a marked decrease in recurrence rates, below 20%, when using a radical treatment for this odontogenic tumor, which can be potentially lethal but is locally aggressive [23–25]. Recent research on ameloblastoma has revealed the existence of various genetic mutations that control cell growth, survival, and tumor development. These findings have sparked renewed interest in exploring non-surgical treatment options for these lesions [12]. Several reports have indicated that many mandibular ameloblastomas have gene mutations, which could be a promising allopathy treatment [26]. Studies on the use of vemurafenib, dabrafenib, and trametinib as comprehensive treatment for ameloblastomas have yielded favorable results, demonstrating substantial reduction in tumor size [23,24].
Even though the primary objective of reconstruction surgery is to regenerate the hard and soft tissue, it is also important to consider neurological interventions. Autogenous nerve grafts should be utilized to secure the underlying neural cells associated with large defects [2,5,6]. In a recent study, allogenic nerve grafts for repairing long-term defects involving the inferior alveolar nerve showed consistently positive results regarding neurosensory outcomes [5]. The study demonstrated that most patients experienced a restoration of superficial cutaneous pain and tactile sensation. After extensive consideration among the surgical and rehabilitative teams and the patient, it was determined that the expenses involved in either an autogenous nerve harvest or obtaining allogenic materials were prohibitive for our patient [11,14]. Therefore, it is advised to prioritize restoration of neural cells. According to a study of 30 patients with inferior alveolar nerve defects caused by benign odontogenic lesions removed without nerve reconstruction, 70% of patients recovered neurosensory function, similarly to allogenic repair studies [15,23,25]. Cortical plasticity, neurosensory adaptation, and the ingrowth of neighboring nerves are proposed pathways for such recovery.
Planning for reconstructive surgery has been transformed by using virtual surgical planning (VSP), making it easier to fabricate models, cutting and drilling guides, and custom gear that can be patient-specific or pre-bent. These products contribute to significantly improved surgical outcomes by reducing operative times and increasing predictability and accuracy [27]. Use of this technology has recently expanded, including the predictive placement of endosseous dental implants. This advancement aims to make prosthetic rehabilitation more efficient by allowing it to be done during the primary reconstruction. It is commonly referred to as “Jaw in a Day”. A recent systematic review and meta-analysis compared computer-assisted and traditional freehand mandibular repair efficiency and accuracy metrics with a fibular free flap [8,11,27]. In the current case report, surgeons discussed the VSP option with the patient, but this treatment plan was rejected due to expense.
The primary objective of reconstructing the mandible is to establish an adequate osseous framework for supporting dental implant insertion. It is crucial to ensure the success of endosseous implant placement in composite free flaps with the objective to establish a solid base for dental prostheses and enhance the ability to chew, speak, and improve facial aesthetics. A comprehensive review was performed to examine the durability of implant prostheses in composite free flaps for mandibular ramus restoration [7]. The studies included in the analysis had different interpretations of implant survival and efficacy. Nevertheless, the analysis revealed that a remarkable 94% of the 1328 implants, whether they were placed in a fibula-free flap or deep circumflex iliac artery flap, were successfully sustained for 5 years. Survival rates did not show any significant variations between the 2 groups [7]. For our patient, we chose a 2-stage approach to oral rehabilitation. When selecting a flap, it is essential to consider the time of endosseous dental implant insertion, due to the potential variability in the dimensional stability of grafted bone following the initial reconstruction. Fortunately, the fibula has a low rate of resorption, maintaining 95% of the original bone volume even 2 years after flap placement [11,12]. In the present case, the ameloblastoma was removed, and the mandible was secured with a graft. Further evaluation was done after the patient had completely recovered, and the placement of endosseus dental implants was planned.
The potentially negative psychological effects of significant orofacial and functional abnormalities caused by extensive surgical care for ameloblastomas cannot be ignored. A recent comprehensive review analyzed the impact of different surgical treatments on health-related quality-of-life indicators for individuals with ameloblastomas. The study revealed positive improvements in various aspects, including appearance, activity, pain, speech, swallowing, chewing, mood, and anxiety [1,5]. However, among the 10 studies evaluated, there was considerable variation in the health measures collected by the 6 validated instruments used to assess the effects of surgical treatment. As expected, out of the 283 patients included in the studies, only 73 received oral rehabilitation [1,5]. This treatment led to significant improvement in the patient’s ability to chew and speak.
Conclusions
Although there may be potential changes in the management of conventional ameloblastoma, effective treatment is currently understood to involve complete removal of the tumor followed by reconstruction of the affected tissue and oral rehabilitation. However, the treatment’s associated morbidity poses significant challenges in terms of functionality and aesthetics, affecting quality of life. It is crucial to have a diverse care team consisting of dentists, oral and maxillofacial surgeons, and prosthodontists, who can effectively utilize the latest technological advancements. This approach is essential for implementing a collaborative management strategy that aims to maximize treatment outcomes for vulnerable groups of patients. Furthermore, it is crucial for the dental team to accept the duty of regular inspection for potential reoccurrence and maintenance of prosthetic devices. This will improve the therapy strategy of long-term success and ensure the patient’s overall health and well-being, including physical, mental, and social aspects.
Figures
References:
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