Intraosseous ameloblastoma

Effectiveness of Resective Surgery in Complex Ameloblastoma of the Jaws: A Retrospective Multicenter Observational Study

Ameloblastoma is a rare, benign, odontogenic tumor of epithelial origin, characterized by locally aggressive, expansive growth. Treatment is controversial due to the risk of relapse. The aim of this multicenter retrospective study was to evaluate the effectiveness of complete resection in cases of complex ameloblastoma, which is considered at a higher risk of recurrence. Patients who met at least one of these criteria were included: recurrence, soft-tissue involvement, complete erosion of internal/external cortical walls with involvement of the inferior margin of the mandible, and invasion of the maxillary sinus or nasal cavity. Demographic data, tumor site, type of surgery, histological features, and follow-up information were collected for each patient. The cohort included 55 patients with a mean follow-up of 108 ± 66 months. A multivariate logistic model was used to evaluate variables independently associated with relapse. There were six soft-tissue or maxillary sinus relapses, with a recurrence rate of 10.9%. Most of them arose in patients previously treated. The statistical analysis identified the maxillary location as a fundamental relapse risk factor. En bloc resection with large surgical safety margins seemed to be effective in preventing the relapses. However, complete resection was less effective in preventing recurrences in the soft tissues or maxillary sinus.

Unicystic Ameloblastoma Mimicking Lateral Periodontal Cyst

Intraosseous unicystic ameloblastoma (UA) is a rare subtype of a true neoplasm of odontogenic epithelial origin: ameloblastoma. Despite its rareness, dealing with UA is problematic. It is usually mistaken for an odontogenic cyst, and biopsy is rarely relevant because of its multiple growth patterns. The biggest challenge remains the treatment choice. When we are faced with a mural UA presenting strong similarities with a lateral periodontal cyst and having high rates of recurrence, how is the balance found between the young age, psychological fragility, postoperative process, and need for diagnostic biopsy? That was our dilemma. Our patient is a 23-year-old man with a mural unicystic ameloblastoma, diagnosed with general anxiety disorder. The final decision was to turn to a simple enucleation because of the small size of the lesion, and its radiological features strongly evoked a lateral periodontal cyst. Besides, his young age, psychological condition, and UA's proximity to the surrounding soft tissues guided us toward simple enucleation. Two years later, no sign of radiological recurrence was noted. However, we are aware of a later possibility of resection in case of recurrence.

Effectiveness of the Conservative Surgical Management of the Ameloblastomas: A Cross-Sectional Study

Ameloblastoma is a benign, but locally aggressive odontogenic neoplasm, whose appropriate therapeutic management remains highly debatable. The aim of this study was to evaluate the reliability and effectiveness of the two conservative surgical therapeutic protocols (curettage with peripheral ostectomy only and curettage plus cryotherapy) for the management of ameloblastomas. About 53 cases of the ameloblastomas treated in 9 years were retrospectively analyzed regarding their clinical, histopathologic, radiographic, and therapeutic data. The results and the postoperative complications related to both the therapeutic protocols were also statistically investigated. A slight female preponderance was seen (1.12:1.0) with a mean age of 27.1 years. The posterior mandible was the most affected site and dental involvement was frequently found. Multilocular lesions causing the alterations of the bone cortices were the most common radiographic findings. Recurrences were seen in 9.4% of the cases and although the patients submitted to curettage plus cryotherapy have shown an increased incidence of wound dehiscence, infection, and paresthesia, only bone sequestration proved to be significantly more frequent in this group compared to the patients treated by curettage with peripheral ostectomy only. The incidence of the recurrences following the conservative management is low and cryotherapy use as an adjuvant tool must be rationally considered.

Alloplastic Temporomandibular Joint Reconstruction Following Recurrent Ameloblastoma Resection

ABSTRACT

Ameloblastomas are benign tumors that most commonly affecting the mandible. The current standard of treatment for ameloblastomas is resection followed by reconstruction that has historically been accomplished through the use of a microsurgical vascularized flaps taken from the iliac crest or fibula. Alloplastic reconstruction methods have gained popularity over recent years with success reported in the reconstruction of many pathologies, including ankylosis, condylar fracture, neoplasia involving extensive resection, severe inflammatory/degenerative temporomandibular joint (TMJ) disease, and congenital TMJ abnormalities. The authors present a patient who successfully underwent ameloblastoma resection and TMJ reconstruction with a custom TMJ Concepts alloplastic implant. The authors also present a review of the literature on alloplastic TMJ reconstruction following ameloblastoma resection. To our knowledge, this is the second report in the literature on the use of a TMJ Concepts implant after ameloblastoma resection.

Directions of mandibular canal displacement in ameloblastoma: A computed tomography mirrored-method analysis

Purpose

This study was performed to investigate mandibular canal displacement in patients with ameloblastoma using a 3-dimensional mirrored-model analysis.

Materials and Methods

The sample consisted of computed tomographic scans of patients with ameloblastoma (n=10) and healthy controls (n=20). The amount of mandibular canal asymmetry was recorded as a continuous variable, while the buccolingual (yaw) and supero-inferior (pitch) directions of displacement were classified as categorical variables. The t-test for independent samples and the Fisher exact test were used to compare groups in terms of differences between sides and the presence of asymmetric inclinations, respectively (P<0.05).

Results

The length of the mandibular canal was similar on both sides in both groups. The ameloblastoma group presented more lateral (2.40±4.16 mm) and inferior (−1.97±1.92 mm) positions of the mental foramen, and a more buccal (1.09±2.75 mm) position of the middle canal point on the lesion side. Displacement of the mandibular canal tended to be found in the anterior region in patients with ameloblastoma, occurring toward the buccal and inferior directions in 60% and 70% of ameloblastoma patients, respectively.

Conclusion

Mandibular canal displacement due to ameloblastoma could be detected by this superimposed mirrored method, and displacement was more prevalent toward the inferior and buccal directions. This displacement affected the mental foramen position, but did not lead to a change in the length of the mandibular canal. The control group presented no mandibular canal displacement.

Atypical periosteal reaction and unusual bone involvement of ameloblastoma: A case report with 8-year follow-up

Unusual radiographic findings of intraosseous ameloblastoma have been reported and discussed. In the case discussed herein, cone-beam computed tomography (CBCT) clearly showed many radiographic features that were ambiguous on conventional radiographs, including an ill-defined periphery, extensive superficial buccal extension with minimal lingual extension, obvious bucco-crestal expansion, and multiple triangular (Codman's triangle-like) areas of periosteal reaction. Based on the above-mentioned findings, the differential diagnosis was a long-term infected benign or low-grade malignant lesion. An incisional biopsy was performed, and the histopathologic diagnosis was acanthomatous ameloblastoma. Recurrence of the lesion was clearly detected on CBCT images at 4 and 8 years after surgery. These unusual radiographic findings have never been reported to be associated with ameloblastoma, and thus may contribute to novel concepts in radiographic interpretation in the future. This report also underscores the important role played by CBCT as a comprehensive diagnostic tool and for definite confirmation of recurrence.

Comparative Study of the Minichromosome Maintenance Proteins Complex (MCM 4/5/6) in Ameloblastoma and Unicystic Ameloblastoma

INTRODUCTION

Solid/conventional ameloblastoma (AM) and unicystic ameloblastoma (UAM) are the most frequent benign epithelial odontogenic tumors located in the maxillary region, and their treatment usually consists of extensive surgical resection. Therefore, it is relevant to study molecular markers to better understand the biological behavior of these tumors. The aim of this study was to describe and compare the expression of proteins related to cellular proliferation: Ki-67 and MCM4-6 complex.

MATERIALS AND METHODS

An immunohistochemistry technique was performed, with antibodies against Ki-67, MCM4, MCM5, and MCM6, in 10 AM and 10 UAM tumors. The results were quantified using label index and analyzed statistically.

RESULTS

AM and UAM had greater expression of MCM6, followed by MCM5, MCM4, and Ki-67 ( P < .05). Immunoexpression of Ki-67 and MCM5 was exclusively nuclear, whereas the expression of MCM4 and MCM6 was nuclear and cytoplasmic.

CONCLUSION

The results suggest that MCM5 is a trustable cell proliferation marker with higher sensitivity compared with Ki-67 and may be useful to predict the biological behavior of AM and UAM. Despite this, further studies are necessary, including a correlation with clinical parameters to confirm these findings.

Biological profile of ameloblastoma and its location in the jaw in 1246 Nigerians

OBJECTIVES

Ameloblastoma is a benign, slow-growing, locally invasive epithelial tumor of odontogenic origin, with unlimited growth capacity and a strong tendency to recur. This multicentric study analyzed ameloblastoma diagnosed in Nigeria among different ethnic groups.

STUDY DESIGN

This retrospective study included ameloblastoma cases diagnosed from 1964 to 2017 at 10 hospitals or medical centers in Nigeria. Age, sex, tribe, and location of the ameloblastoma in the jaw were analyzed. Associations between variables were tested by using χ² and Fisher's exact test.

RESULTS

A total of 1246 ameloblastoma cases were recorded (mean patient age 32.51 ± 14.54 years; range 4-86 years; male-to-female ratio 1.2:1). Approximately 60% of ameloblastoma cases occurred in young adults (age range 18-40 years). Ninety-eight lesions were located in the maxilla and 1103 in the mandible; the posterior mandible was the most common site (31.3% on the right and 26.5% on the left, respectively), followed by the anterior (26.0%) mandible. No significant differences were noted in the distribution of ameloblastoma within the tribes with respect to age (P = .92) and sex (P = .71).

CONCLUSIONS

The mandible is a common site of ameloblastoma in patients in Nigeria, and in most cases, it occurs in young adults. Early presentation, diagnosis, and treatment are important to reduce postoperative disfigurement and morbidity.

Biomimetic Tissue-Engineered Bone Substitutes for Maxillofacial and Craniofacial Repair: The Potential of Cell Sheet Technologies

Maxillofacial defects are complex lesions stemming from various etiologies: accidental, congenital, pathological, or surgical. A bone graft may be required when the normal regenerative capacity of the bone is exceeded or insufficient. Surgeons have many options available for bone grafting including the "gold standard" autologous bone graft. However, this approach is not without drawbacks such as the morbidity associated with harvesting bone from a donor site, pain, infection, or a poor quantity and quality of bone in some patient populations. This review discusses the various bone graft substitutes used for maxillofacial and craniofacial repair: allografts, xenografts, synthetic biomaterials, and tissue-engineered substitutes. A brief overview of bone tissue engineering evolution including the use of mesenchymal stem cells is exposed, highlighting the first clinical applications of adipose-derived stem/stromal cells in craniofacial reconstruction. The importance of prevascularization strategies for bone tissue engineering is also discussed, with an emphasis on recent work describing substitutes produced using cell sheet-based technologies, including the use of thermo-responsive plates and the self-assembly approach of tissue engineering. Indeed, considering their entirely cell-based design, these natural bone-like substitutes have the potential to closely mimic the osteogenicity, osteoconductivity, osteoinduction, and osseointegration properties of autogenous bone for maxillofacial and craniofacial reconstruction.

The landscape of genetic alterations in ameloblastomas relates to clinical features

Ameloblastoma is a mostly benign, but locally invasive odontogenic tumor eliciting frequent relapses and significant morbidity. Recently, mutually exclusive mutations in BRAF and SMO were identified causing constitutive activation of MAPK and hedgehog signaling pathways. To explore further such clinically relevant genotype-phenotype correlations, we here comprehensively analyzed a large series of ameloblastomas (98 paraffin block of 76 patients) with respect to genomic alterations, clinical presentation, and histological features collected from the archives of three different pathology centers in France, Germany, and Turkey. In good agreement with previously published data, we observed BRAF mutations almost exclusively in mandibular tumors, SMO mutations predominantly in maxillary tumors, and single mutations in EGFR, KRAS, and NRAS. KRAS, NRAS, PIK3CA, PTEN, CDKN2A, FGFR, and CTNNB1 mutations co-occurred in the background of either BRAF or SMO mutations. Strikingly, multiple mutations were exclusively observed in European patients, in solid ameloblastomas and were associated with a very high risk for recurrence. In contrast, tumors with a single BRAF mutation revealed a lower risk for relapse. We here establish a comprehensive landscape of mutations in the MAPK and hedgehog signaling pathways relating to clinical features of ameloblastoma. Our data suggest that ameloblastomas harboring single BRAF mutations are excellent candidates for neo-adjuvant therapies with combined BRAF/MEK inhibitors and that the risk of recurrence maybe stratified based on the mutational spectrum.

Rare case of giant unicystic ameloblastoma: Luminal variant

OBJECTIVE AND IMPORTANCE

Ameloblastoma is a locally aggressive benign tumor, commonly occurring in the mandible. While giant ameloblastoma of multicystic or plexiform variant have been reported, the authors report a rare case of giant unicystic ameloblastoma of luminal variant, which was treated by compartmental resection and planned for delayed reconstruction.

CLINICAL PRESENTATION

A 46 year old male patient reported to the oral surgery out-patient department with a swelling of the left side mandible region of 2 years duration. He had undergone ayurvedic treatment for the same with no improvement. The size of the lesion on presenting was approximately 9 × 12 cm.

INTERVENTION

Compartmental resection with plan for secondary reconstruction, after adequate follow up period.

CONCLUSION

While conservative management is being explored as a treatment option for unicystic ameloblastoma, resection is still the standard of care regardless of the histopathological subtype for giant lesions.

What Is Important for Confirming Negative Margins When Resecting Mandibular Ameloblastomas?

PURPOSE

The purpose of this study was to assess the utility of intraoperative radiographs and frozen sections in achieving negative margins and preventing recurrence of mandibular ameloblastomas.

MATERIALS AND METHODS

This was a retrospective cohort study of patients who underwent resection (≥1 cm) of mandibular ameloblastomas from 2005 through 2015. Patients were included if they had at least 1-year follow-up and complete records. Demographic variables included age, gender, and type of resection (segmental vs marginal). Predictor variables were type of margin assessment: 1) frozen section, 2) intraoperative ex vivo specimen radiograph, 3) both, or 4) none. The outcome variables were final margin status and recurrence rate. Accuracy of intraoperative radiographic margins was determined by comparison with histologic margin distance. Descriptive statistics were conducted with the Fisher exact test.

RESULTS

The study sample consisted of 35 patients (47.5 ± 20.4 yr old; 16 men) who underwent 25 segmental and 10 marginal resections. Ten had frozen sections only, 3 had ex vivo specimen radiographs only, 10 had no intraoperative measurements, and 12 had both. There were no positive frozen sections. One patient had a positive posterior bony margin at final pathology despite negative frozen section histology. There was no difference in recurrence rate at latest follow-up among cohorts. The anterior radiographic margin was 11.8 ± 5.9 mm compared with 11.5 ± 7.5 mm by histology (P = .124). The posterior radiographic margin was 12.3 ± 5.3 mm compared with 9.8 ± 6.5 mm histologically (P = .546). Margin distances that were at least 5 mm when measured with specimen radiographs had histologic margin distances of at least 5 mm in 25 of 30 resection margins (83.3%).

CONCLUSION

Resection of ameloblastoma with planned margins of at least 1 cm is sufficient to prevent recurrence of ameloblastoma. Achieving a radiographic margin of at least 5 mm provided a histologic margin of at least 5 mm 83.3% of the time.

Desmoplastic variant of ameloblastoma of the maxilla: A case report

The desmoplastic variant of ameloblastoma is a rare form of ameloblastoma characterized by unique radiographic and histologic features. A 46-year-old female was referred to our hospital, complaining of swelling in the left upper lip area. Radiographic findings revealed an ill-defined multilocular lesion with a large cystic lesion and thick sclerotic trabeculae on the left anterior maxilla. After the patient underwent partial osteotomy, histologic analysis revealed a desmoplastic ameloblastoma with no evidence of a hybrid lesion or cyst formation. The radiographic findings in the present case were different from those described in previous case reports. These findings are of special importance due to the unfamiliar radiographic and histologic features of this lesion.

Recurrent giant mandibular ameloblastoma in young adults

BACKGROUND

The purpose of the study was to define the most appropriate management of the giant mandibular ameloblastoma (GMA) in young adults.

METHODS

A retrospective study was performed on patients with GMA <30 years old. The data collected included initial treatment, tumor margins, reconstruction, and follow-up. Patients evaluated speech, chewing, swallowing, and facial appearance after definitive treatment.

RESULTS

Thirteen patients were identified with recurrent solid/multicystic disease requiring further treatment. Definitive treatment involved segmental mandibulectomy and reconstruction with free fibular flap in all patients. Seven patients had immediate reconstruction (group A) and 6 had secondary (group B). Mandibular resection was planned at least 2 cm beyond the radiological limit, free margins were achieved in all patients, and all flaps were transplanted successfully. In group A, functional score was 13.7 ± 0.45 and facial appearance score was 4.5 ± 0.49, whereas in group B were 11.16 ± 0.37 and 3.3 ± 0.5, respectively (both p < .05).

CONCLUSION

Aggressive resection of the GMA and immediate reconstruction is strongly advised. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1947-E1954, 2016.

Ameloblastomas: clinicopathological features from 70 cases diagnosed in a single oral pathology service in an 8-year period

Ameloblastomas are odontogenic tumors that can present some distinct clinicopathological profiles when comparing different populations and studies. Objectives: The aim of the present study was to analyze the clinicopathological features from a series of ameloblastomas diagnosed in a single Oral Pathology service in Brazil in an 8-year period. Study Design: The files were revised and all cases diagnosed as ameloblastomas in the period were retrieved. All hematoxylin and eosin stained histological slides were reviewed and all clinical and radiological information were obtained through a review of the laboratory forms. Data were descriptively analyzed and a comparison was performed with the different ameloblastomas subtypes. Results: Seventy ameloblastomas composed the final sample, including 57 (81%) solid/multicystic, 9 (13%) unicystic, 2 (3%) desmoplastic and 2 (3%) peripheral ameloblastomas. Mean age of the affected patients was in the forth decade of life and there was a slight male predominance. Most tumors presented as multilocular radiolucencies, were located in the posterior mandible and showed the follicular and plexiform histological patterns. There was no difference on the mean age of the patients affected by solid and unicystic ameloblastomas. Conclusions: The present results showed that the clinicopathological features of the ameloblastomas included in this Brazilian sample were similar to the features described in most other worldwide populations.

Key words:Ameloblastoma, solid, unicystic, review, epidemiology, histology.

Role of immunomarkers in the clinicopathological analysis of unicystic ameloblastoma

Purpose. The clinical behavior of unicystic ameloblastoma varies according to its subtype. The assessment of its proliferative capacity, neovascularization, and invasiveness using relevant immunomarkers may aid in appropriate surgical therapeutic protocol. Methods. 18 cases of clinically and histologically confirmed unicystic ameloblastoma, categorized as luminal, intraluminal, or mural subtypes, were analyzed retrospectively. Immunomarkers such as Ki-67, CD34, MMP-2, and MMP-9 were studied to evaluate their behavior. Results. Labeling index of Ki-67 was 4.25% in the intraluminal subtype, compared with 2.14% in the luminal and 4.04% in the mural variant (P = 0.3). CD34 immunostaining was significantly higher in the mural variant (43 per high power field) than the other two subtypes (P = 0.04). MMP-2 and MMP-9 were strongly expressed in mural, moderately in intraluminal, and weakly to absent in luminal variant. Conclusions. High proliferative index, angiogenesis, and protease activity in the mural ameloblastoma, ascertained by the expression of these markers, confirm its aggressive phenotype. The intraluminal and luminal subtype exhibiting decreased expression are compatible with their indolent clinical behavior.

Treatment of recurrent mandibular ameloblastoma

Ameloblastoma is a locally invasive benign odontogenic tumor with a high rate of recurrence in the long term. The authors conducted a retrospective study of patients with mandibular ameloblastoma in order to evaluate recurrent ameloblastoma management. The study included data from 31 patients over a period of 10 years. Data collected included age, gender, tumor location, histological findings, initial treatment, number of recurrences and year of onset, type of treatment of recurrence, reconstruction and follow-up. Recurrences were detected in nine patients (29%). Tumor recurrences appeared at 32 months on average following the initial surgical procedure. Recurrences were associated mainly to inadequate initial therapeutic approach and were treated by bone resection with a safety margin of at least 1 cm beyond the radiographically visible margins. Immediate reconstruction of bone defects was performed with grafts or free flaps.

Graft necrosis occurred after iliac crest reconstruction after mandibular segmental resection of ameloblastoma

Ameloblastoma is an uncommon benign odontogenic neoplasm of the maxillofacial region constituting less than 1% of tumors of the oral cavity. Ameloblastomas have been categorized broadly into 3 biologic variants: cystic (unicystic), solid, and peripheral. Unicystic ameloblastoma is a rare and less aggressive variant of ameloblastoma. The aim of this report is to describe a case of cystic ameloblastoma treated with segmental resection and iliac graft reconstruction. The possible reasons of graft failure seen in our patient at the early stage of the healing were also discussed.

Unicystic ameloblastoma in 3 year old paediatric patient - A rare entity

Unicystic ameloblastoma (UA) is a benign epithelial odontogenic tumor of the jaws that commonly occurs in 2nd and 3rd decade of life. In fact, this entity is rare in children under 12 years of age. It is characterised as a distinct variant of ameloblastoma, exhibiting a less aggressive behaviour and a lower rate of recurrence than solid conventional ameloblastoma. There are very few reported cases of UA occurring in children below five years of age. The purpose of this case report is to describe a case of UA involving the crown of an unerupted maxillary second premolar in a 3 year old girl. The pathogenesis, clinical appearance, radiographic presentation, histological findings and management of the tumour have also been discussed.

Achieving adequate margins in ameloblastoma resection: the role for intra-operative specimen imaging. Clinical report and systematic review

Background

Ameloblastoma is a locally aggressive odontogenic neoplasm. With local recurrence rates reaching 90%, only completeness of excision can facilitate cure. Surgical clearance has widely been based on pre-operative imaging to guide operative excision margins, however use of intra-operative specimen x-ray or frozen-section has been sought to improve clearance rates, and advanced imaging technologies in this role have been proposed. This manuscript aims to quantify the evidence for evaluating intra-operative resection margins and present the current standard in this role.

Method

The current study comprises the first reported comparison of imaging modalities for assessing ameloblastoma margins. A case is presented in which margins are assessed with each of clinical assessment based on preoperative imaging, intra-operative specimen x-ray, intra-operative specimen computed tomography (CT) and definitive histology. Each modality is compared quantitatively. These results are compared to the literature through means of systematic review of current evidence.

Results

A comparative study highlights the role for CT imaging over plain radiography. With no other comparative studies and a paucity of high level evidence establishing a role for intra-operative margin assessment in ameloblastoma in the literature, only level 4 evidence supporting the use of frozen section and specimen x-ray, and only one level 4 study assesses intra-operative CT.

Conclusion

The current study suggests that intra-operative specimen CT offers an improvement over existing techniques in this role. While establishing a gold-standard will require higher level comparative studies, the use of intra-operative CT can facilitate accurate single-stage resection.

Osteoplastic ameloblastoma: a case report and literature review

Ameloblastoma with bone formation is rare. We report a case of a 55-year-old woman with ameloblastoma accompanied by prominent osteoplasia. Histopathological examination exhibited an abundant stromal component between tumor nests. Therefore, she was diagnosed as the desmoplastic variant, except for the numerous bone trabeculae. The distinction between new bone formation and invasion of the bone marrow poses a problem. A thin rim of fibrous bone that can be accentuated by Masson-trichrome staining suggests the former.

Difficulties in the diagnosis of plexiform ameloblastoma

BACKGROUND

Plexiform ameloblastoma is a rare and benign odontogenic tumor which may reach grotesque proportions affecting over a region of lower molars. The correct diagnosis is essential to reduce this risk of local recurrences and obtain an effective treatment.

CASE REPORT

A 10-year-old female patient, Caucasian, presented a complaint of painless facial asymmetry. The clinical and imaginological examinations showed an increase in volume in the left mandibular body related to radiolucent unilocular injury near the apex of the first molar, expansion of the vestibular cortical bone, and tooth root resorption ipsilaterally. The former intraosseous biopsy suggested an aneurysmal bone cyst. In reopening the previous marsupialization, a new biopsy was performed with histopathologic findings compatible with plexiform ameloblastoma associated with acute inflammation. Curettage was performed in the region associated with cryotherapy. At the last biopsy, the diagnosis of plexiform ameloblastoma was confirmed with multiple cystic formations and areas of foreign body reaction. The patient is being followed for 2 years and yet remains clinically and radiographically stable with no recurrence.

DISCUSSION

This case reports the importance of selecting the correct area of biopsy of an intraosseous extended lesion to contribute to the diagnosis and treatment of plexiform ameloblastoma.