Odontogenic myxoma: clinico-pathological, immunohistochemical and ultrastructural findings of a multicentric series

Clinicopathologic and imaging features of odontogenic myxomas: a multi-institutional study

PURPOSE

This study aims to report clinicopathologic and imaging features of odontogenic myxomas (OM), highlighting uncommon findings.

METHODS

Clinicopathologic and imaging data of OMs diagnosed in the five Brazilian diagnostic pathology centers were collected and analyzed.

RESULTS

The series comprised 42 females (68.9%) and 19 males (31.1%), with a 2.2:1 female-to-male ratio and a mean age of 34.5±15.4 years (range: 4-80). Clinically, most OMs presented as painless intraoral swelling (n = 36; 70.6%) in the mandible (n=37; 59.7%). Multilocular lesions (n=30; 83.3%) were more common than unilocular lesions (n=6; 16.7%). There was no statistically significant difference between the average size of unilocular and multilocular OMs (p=0.2431). The borders of OMs were mainly well-defined (n=24; 66.7%) with different degrees of cortication. Only seven tumors caused tooth resorption (15.9%), while 24 (54.5%) caused tooth displacement. Cortical bone perforation was observed in 12 (38.7%) cases. Morphologically, OMs were characterized mainly by stellate or spindle-shaped cells in a myxoid background (n=53; 85.5%). Surgical resection was the most common treatment modality (n=15; 65.2%), followed by conservative surgery (n=8; 34.8%). Outcomes were available in 20 cases (32.3%). Seven of these patients had local recurrence (35%). Enucleation was the treatment with the highest recurrence rate (4/7; 57.1%).

CONCLUSIONS

OM has a predilection for the posterior region of the jaws of female adults. Despite their bland morphological appearance, they displayed diverse imaging features. Clinicians must include the OM in the differential diagnosis of osteolytic lesions of the jaws. A long follow-up is needed to monitor possible recurrences.

Title of the article: diagnostic markers for odontogenic tumors: an insight: a review

Odontogenic tumors are a group of tumors that originate from the tissues associated with tooth development and are classified into benign or malignant based on their behavior and characteristics. Tumor markers are substances that can be found in the blood, urine, or tissues of individuals with cancer. They are the substances produced either by tumor cells itself or by the body in response to tumor growth, can sometimes be used in the diagnosis, prognosis, and monitoring of various types of tumors. However, the use of tumor markers in odontogenic tumors is not as common as it is in other types of cancers, and their utility in this context is limited. Tumor markers are not the main tools for diagnosing cancer; instead, they serve as supplementary laboratory tests to aid in the diagnosis. Researchers continue to investigate potential biomarkers to improve our understanding of these tumors and their behavior. With this concept in mind, the objective of this study is to elucidate the key diagnostic markers essential for diagnosing odontogenic tumors.

Surgical management of odontogenic myxomas: A case series

INTRODUCTION

Odontogenic myxoma is a relatively rare bone tumor involving exclusively the jaws. Despite its benign nature, odontogenic myxoma can exhibit aggressive, locally invasiveness and has a high potential of recurrence. Surgical treatment can be conservative of radical. The choice of surgical procedure is controversial, and there are no established guidelines.

CASE SERIES PRESENTATION

We present a case series of three cases of odontogenic myxomas. This case series illustrates the variability of the radioclinical presentation of odontogenic myxoma and the resulting surgical management, ranging from simple enucleation to mandibular interruptive resection surgery with free flap reconstruction.

DISCUSSION AND CONCLUSION

Through this case series, we highlighted and described decision criteria contributing to treatment choice and summarized this in an algorithm. Radiological tumor characteristics and also patient specific factors such as age need to be considered to make a personalized decision to each patient.

Extraskeletal myxoid chondrosarcoma of the gingival: a rare case report and review of the literature

BACKGROUND

Extraskeletal myxoid chondrosarcoma (EMC) is a rare malignant tumor described in the head and neck region, especially in the gingival. We present one case arising in the gingival of right mandible, and briefly reviewed the related literature.

CASE PRESENTATION

A 24-year-old male patient with a lesion of 3.5*2.0 cm in buccal gingival of right posterior mandible for 2 months. The tumor was composed of cartilaginous structures and myxoid matrix. Immunohistochemical(IHC) showed that the tumor cells to be positive for vimentin, focally positive for S-100, negative for calponin, SMA, SOX10. The Ki-67 labelling index was 80%. Fluorescent in situ Hybridization (FISH) was positive for NR4A3 rearrangement.

CONCLUSIONS

Due to its unusual site and low incidence in the oral region, a combination of histological findings, immunohistochemistry, and molecular pathology as well as differential diagnosis with other diseases should be taken into consideration in the process of clinical diagnosis and treatment.

Sinonasal Myxoma: A Distinct Entity or a Myxoid Variant of Desmoid Fibromatosis?

Sinonasal myxoma (SNM) is a rare benign mesenchymal tumor that arises in the sinonasal cavity or maxilla and almost exclusively affects young children. Currently, it is considered a specific entity, but its molecular characteristics have not been reported. Lesions diagnosed as SNM and odontogenic myxoma/fibromyxoma (OM/OFM) were identified from the participating institutions, and the clinicopathologic features were recorded. Immunohistochemistry for β-catenin was performed on all cases with available tissue. Next-generation sequencing (NGS) was performed on all SNM cases. Five patients with SNM were identified, including 3 boys and 2 girls with an age range of 20-36 months (mean: 26 months). The tumors were well-defined, centered in the maxillary sinus, surrounded by a rim of woven bone, and composed of a moderately cellular proliferation of spindle cells oriented in intersecting fascicles in a variably myxocollagenous stroma that contained extravasated erythrocytes. Histologically, the tumors resembled myxoid desmoid fibromatosis. Three tested cases showed nuclear expression of β-catenin. In 3 tumors, NGS revealed intragenic deletions of APC exons 5-6, 9 and 15, or 16, respectively, with concurrent loss of the other wild-type copy of APC, predicted to result in biallelic inactivation. The deletions were identical to those that occur in desmoid fibromatosis, and copy-number analysis raised the possibility that they were germline. In addition, one case showed possible deletion of APC exons 12-14, and another case exhibited a CTNNB1 p.S33C mutation. Ten patients with OM/OFM were identified, including 4 women and 6 men (mean age: 42 years). Seven tumors involved the mandible, and 3 the maxilla. Histologically, the tumors differed from SNM, and all cases lacked nuclear expression of β-catenin. These findings suggest that SNM represents a myxoid variant of desmoid fibromatosis that often arises in the maxilla. Because the APC alterations might be germline, genetic testing of the affected patients should be considered.

A Case of Odontogenic Myxoma of the Mandible with Expansion to the Alveolar Crest – Comparison of Imaging Findings and Pathological Findings: A Case Report

Background:

An odontogenic myxoma is an intraosseous tumor characterized by stellate and spindle-shaped cells embedded in an abundant myxoid or mucoid extracellular matrix. We herein describe an odontogenic myxoma that expanded not only to the bone marrow but also to the outside of the alveolar bone. Diagnosis of an odontogenic myxoma in a tooth-deficient region by imaging findings alone was difficult because the positional relationship between the tumor and the tooth is unknown. Furthermore, some of these odontogenic myxomas reportedly show rapid growth.

Case Report:

Here, we present the case of a patient, a 44-year-old man, who had a hard, bone-like swelling on his right mandible molar region and mild paresthesia on his right cheek. An odontogenic myxoma and ameloblastoma were suspected based on the imaging findings; however, pathological examination of the biopsy led to a diagnosis of odontogenic myxoma. Right segmental mandibulectomy was performed, and there was no recurrence observed after surgery.

Conclusion:

To improve the accuracy of imaging diagnosis, it is important to compare the imaging findings with the pathological findings of the surgical specimen. This comparison in the present case revealed differences in the magnetic resonance imaging signal intensity in regions with different types of cell components.

Odontogenic myxoma with pain and uncommon histological feature in the mandible: A case report and review the literature

Odontogenic myxoma (OM) is a rare benign painless, slow-growing lesion with local aggressive behavior. Pain and sensory disturbance and fibro-osseous appearance in histopathology have been rarely reported in OM. The authors reported a 52-year-old male case presented with a large gingival mass around a mobile mandibular right first molar extended to the distal aspect of the third molar. Microscopic examination of the incisional and excisional biopsy revealed an OM with numerous newly formed bone or cementum-like material present throughout the specimen like those seen in fibro-osseous lesions. For avoiding to recurrence, a segmental mandibulectomy was performed and a metal plate was inserted to the right mandible defect under general anesthesia. Rehabilitation was completed with the placement of implants. We review and discuss about this variety.

Central Odontogenic Myxoma: A Radiographic Analysis

Objective

This study aimed to determine the radiographic characteristics of odontogenic myxomas (OMs) and their associations.

Materials and Methods

The study enrolled radiographs of patients taken between 2005 and 2019 with a confirmed histopathological diagnosis of central OM. OM radiographic features were evaluated, including location, border, locularity, involved area, the number of included teeth, root resorption, tooth displacement, bone expansion, bone perforation, and periosteal reaction. Fisher's exact test was used for statistical analysis.

Results

Significant associations were found between the OM border and the affected jaw (p=0.036), locularity (p=0.036), involved areas (p=0.009), and bone perforation (p=0.036). OMs with an ill-defined border were associated with maxillary lesions, multilocularity, dentate areas, and cortical bone perforation. The number of included teeth (2 or fewer or 3 or more) was significantly associated with locularity (p=0.010), involved area (p=0.045), and bone expansion (p=0.010). Larger OMs including 3 or more teeth, were associated with a multilocular appearance, dentate areas, and bone expansion.

Conclusion

The border of OM and the number of included teeth are related to other radiographic appearances. Understanding these relationships could help in treatment decisions and help better understand the nature of OM.

Large myxomatous odontogenic tumor in the jaw: a case series

Objectives

Myxomatous odontogenic tumors (MOTs) are the third most common odontogenic tumors in the oral and maxillofacial region. Due to its slow-growing, but locally invasive nature, the tumor is usually detected by accident or only when it becomes a large mass, which causes facial deformity.

Materials and Methods

Current study reports three unusual cases of MOT including huge myxoma involve the mandible in middle-aged man, MOT with ossifying fibroma pattern in mandible, and MOT in maxilla of young female patient. The diagnosis and treatment strategy of MOTs was also summarized and updated.

Results

In reported three cases of patients with large MOTs, surgical treatment was indicated with fibular free flap reconstruction in the mandible and plate reconstruction in the maxilla. The tumors were successfully treated with radical resection and did not show signs of recurrence during the follow-up period.

Conclusion

Surgical treatment indication depends on size, the position of the lesion, patient systemic condition and surgeon individual experience. In the case of a large tumor, radical resection and reconstruction is the standard surgical strategy. The conservative surgical treatment including enucleation with wide curettage is still under controversy. The recurrence rate for MOTs is significantly high, up to 30%, therefore long-term follow-up is essential.

The use of Three-Dimensional Printed Technology for Mandibular Reconstruction in a Rare Case of Giant Odontogenic Myxofibroma

ABSTRACT

Odontogenic myxofibroma is a benign odontogenic tumor of mesenchymal tissue that generally originates from the mandible. It is an extremely rare tumor accounting for approximately 2% of all odontogenic tumors. In this report, the authors presented a giant right mandibular mass that extends to the angle of the mandible and displacing the tongue laterally caused significant malocclusion, pain, and impaired oral intake. The tumoral involvement of the mandibula required a partial mandibulectomy with the resection of right mandibular ramus, body, and bilateral parasymphysis. Right mandibular condyle was preserved. The mandibular defect was reconstructed with a fibula free flap. Three-dimensional printed maxillofacial bone model of the patient was used as contour modeling and guide. Histopathologic examination confirmed the diagnosis as odontogenic myxofibroma.The purpose of the report is to present a very rare case of odontogenic myxofibroma and its general characteristics, radiological features, differential diagnosis, surgical management, and the use of three-dimensional printing technology in the field of mandibular reconstruction.

Multidisciplinary Approach to Rehabilitation after Tumor Resective Jaw Surgery: A 9-Year Follow-Up

A 36-year-old male patient presented at the Department of Maxillofacial Surgery, University Hospital Clinic Zagreb in December 2010 due to a swelling of the left body of the mandible that was noticed 4 months earlier. The patient was referred regarding an atypical clinical and radiological finding in the form of a multicystic appearance in the corpus of the left mandible and teeth mobility in the same region. A probatory biopsy was performed under local anesthesia and sent for histopathologic examination which reported odontogenic myxoma. The tumor was removed with a marginal resection of the mandible from the left first incisor to the left second molar. Two years after surgery, in January 2013, the patient was referred to the oral surgeons for implant-prosthodontic rehabilitation. Two narrow implants were placed at positions 32 and 36, and three months afterwards, implant-retained denture was made using locator connections to compensate lost teeth and to correct the ratio of soft tissues and facial contours. The patient was followed-up for 9 years without any functional and aesthetic problems. Loosing function and aesthetic morbidity, after radical surgical treatment, often have compromised the quality of life of this group of patients. It is important to highlight the need for multidisciplinary collaboration for the complete rehabilitation of the patient after surgical oncology of the maxillofacial region.

Mandibular odontogenic myxoma in a paediatric patient

Odontogenic myxoma (OM) are benign, locally aggressive tumours that are rarely found in the paediatric maxillofacial region. OMs derive from mesenchymal odontogenic tissue. We describe the management of a 3-year-old girl who presented with a large right-sided mandibular lesion. Her treatment included conservative excision, curettage and peripheral ostectomy. A literature review was performed which calls into question the dogmatic practice of resection with 1 to 1.5 cm margins. Treatment approaches to the OM could potentially be altered in the paediatric patient.

Odontogenic myxoma: ambiguous pathology of anterior maxilla

Swellings in the anterior maxilla are uncommon and if present can be deemed as paradoxical conundrums presenting diagnostic and therapeutic dilemmas. Odontogenic myxoma is a rare, locally aggressive lesion that is primarily seen affecting the mandibular posterior region in association with an impacted tooth. It is found to be associated with odontogenesis. Treatment is usually surgical, with extent varying from curettage to resection. This report describes a rare case of odontogenic myxoma of the anterior maxilla in a 14-year-old boy, with an emphasis on its epidemiology, clinical presentation, histopathology, diagnosis and treatment planning.

Odontogenic Myxoma: A 23-Year Retrospective Series of 38 Cases

Odontogenic myxoma (OM) is an uncommon benign odontogenic tumor arising in the jaw. Though it has slight histologic overlap with other entities, definitive diagnosis is imperative considering the tumor's aggressive nature, high recurrence rate, and necessity of radical surgical intervention in large-sized lesions. With IRB approval, a retrospective search of the University of Florida College of Dentistry Oral Pathology Biopsy Service archives from 1994 to 2017 for diagnosis of OM of the jaw was performed. Biopsy reports and original slides for each case were assessed and reviewed along with any accompanying radiographs to confirm the diagnosis. Immunohistochemical staining was utilized to exclude entities with histologic overlaps, such as intraosseous myxoid neurofibroma. A total of 38 cases were included. The patients' age ranged from 6 to 84 years, with a mean age of 37.47 years. Females comprised two-thirds of the cases (n = 25) versus males (n = 13). The mandible was the most affected at 60.5% (n = 23), followed by maxilla 39.4% (n = 15). Posterior jaw involvement was higher than anterior in both the mandible (n = 20 versus n = 3) and the maxilla (n = 11 versus n = 4). Most lesions presented clinically as expansile masses with variable radiographic appearance. The clinical impression from submitting providers included "gelatinous masses", abscesses, odontogenic lesions, fibro-osseous lesions, soft tissue or bone neoplasms, and reactive gingival lesions. A consensus of odontogenic myxoma as a diagnosis was rendered for 30 cases (79%), while in 8 cases (21%) that exhibited a more fibrous stroma was identified as fibromyxoma. OM may exhibit a varied demographic and clinical profile with a wide spectrum of histologic presentations. Pathologists should be sentient of this variability in order to arrive at an accurate diagnosis and correctly manage these patients.

Odontogenic Myxoma: Systematic review and bias analysis

BACKGROUND

Odontogenic myxoma (OM) is a rare neoplasm, which originates from odontogenic ectomesenchyme. There is no study in the literature that analyses the best standards for OM diagnosis and how the treatment modalities may influence the recurrence rates.

OBJECTIVE

To evaluate the best standards for odontogenic myxoma (OM) diagnosis and treatment, and how these may influence the recurrence rates.

STUDY DESIGN

Two independent researchers performed a systematic review in many databases. Fifty-two eligible studies were included for qualitative analysis. Bias analysis was conducted according to Oxford Centre for Evidence-Based Medicine.

RESULTS

A total of 1363 OM cases were reported on, and female gender with average age of 27 years is the most common patient profile. Conventional microscopic findings were observed in 93.43% of the reported cases. In 57.49% of the cases, multilocular radiographic appearance was present, followed by unilocular appearance (32.87%). Posterior mandible was the site with the major prevalence, while surgical resection was the most common treatment modality, followed by enucleation. Recurrence rates for both treatment modalities were approximately close (13.04% and 25.0%, respectively).

CONCLUSION

The correct diagnosis of OM relies on the association of clinical, radiographic and microscopic findings. About imaging examinations, panoramic radiography and computed tomography are sufficient for the evaluation of OM. Recurrence rates were closely among the two most used surgery treatments. So according to some clinical-radiological aspects, conservative surgery may be preferred than aggressive surgery modalities.

Sinonasal Myxoma: A Distinct Lesion of Infants

An 11 month old Caucasian male presented with swelling of the right side of the nose and buccal vestibule of unknown duration. Radiographic images revealed a well-circumscribed, hypodense soft tissue mass with a peripheral hyperdense circumference involving the anterior aspect of the right maxilla. The lesion extended from the inferior aspect of the orbital rim superiorly to the maxillary bone inferiorly without invading any nearby structures. The lesion was completely resected via combined extraoral and intraoral approach. The clinical, radiographic, histologic and immunohistochemical features of a sinonasal myxoma in an infant are discussed.

Odontogenic myxomas lack PDGFRB mutations reported in myofibromas

BACKGROUND

The molecular pathogenesis of odontogenic myxoma has not been established yet. Considering that odontogenic myxoma may show myofibroblastic differentiation and myxoid areas can be observed in intra-osseous myofibromas, we tested the hypothesis whether both tumors share a common molecular profile. As recent studies have reported PDGFRB recurrent driver mutations in myofibroma, we evaluated PDGFRB mutations in odontogenic myxomas.

METHODS

A convenience sample of 15 odontogenic myxomas cases was selected. We direct sequenced PDGFRB exons 12 and 14, where p.R561C (c.1681C>T) and p.N666K (c.1998C>G) hotspot mutations have been reported among others in single and/or multiple myofibromas.

RESULTS

All 15 odontogenic myxoma samples were successfully sequenced, and all 15 had wild-type sequences for the PDGFRB mutations investigated.

CONCLUSION

Our findings suggest that PDGFRB mutations do not play a role in odontogenic myxoma pathogenesis, which might be helpful in the differential diagnosis of challenging cases.

Primordial odontogenic tumor: a case report and literature review

Background

A primordial odontogenic tumor (POT) is a rare, benign, mixed epithelial and mesenchymal odontogenic tumor that has been included as a new entity in the latest World Health Organization (WHO) classification (2017). POT consists of dental papilla-like myxoid connective tissue covered with a delicate membrane of ameloblastic epithelium. Only 15 cases have been documented worldwide, and here, we report the sixteenth case and the first one of South Korea.

Case presentation

An asymptomatic lesion was discovered as an incidental radiographic finding in a 10-year-old boy. The patient had no complaints about the lesion. Cone-beam computerized tomograms revealed a round cavity with a defined cortical border measuring approximately 5 × 5 × 5 mm in size. The lesion was a POT. The patient was treated with enucleation. The tumor showed no recurrence for one year.

Conclusion

This is the first report of POT in South Korea using the novel diagnosis of POT after it was recognized and defined in the latest WHO classification. This novel diagnosis will be useful for pathologists and clinicians in diagnosing and differentiating this new and rare disease from other odontogenic tumors.

Long-Term Follow-Up after Conservative Surgical Treatment of Odontogenic Myxoma: A Case Report and Literature Review

Odontogenic myxoma (OM) is a relatively rare, benign odontogenic tumor with locally aggressive behavior, but it is a nonmetastasizing neoplasm of the jaw bones. Although radical resection with an appropriate surgical margin is recommended, emerging evidence has suggested that a more conservative approach will result in acceptable recurrence rates with less morbidity if careful long-term follow-up is provided. A 56-year-old Japanese man with odontogenic myxoma of the left mandible was conservatively treated by surgical enucleation and curettage because he desired functional and cosmetic preservation. During a follow-up period of 100 months, the patient has remained clinically and radiologically free of recurrence. As far as we can ascertain, 20 reports published after 1990 described 37 patients with mandibular OM that had been treated by conservative surgery. Tumors recurred during a mean follow-up of 49.2 ± 42.8 months in 7 (18.9%) patients, and only one of five patients who were followed up for over 100 months developed recurrence. The rate of recurrence decreased from 24.0% to 8.3% when follow-up exceeded 60 months. Although enucleation and curettage have proven effective, the risk of recurrence remains considerable and long-term follow-up is indispensable. More evidence of long-term outcomes after conservative surgery for OM is needed.

Odontogenic myxoma: An updated analysis of 1,692 cases reported in the literature

The aim of the present study was to integrate the available data published on odontogenic myxoma (OM) into a comprehensive analysis of its clinical/radiological features. Electronic search undertaken in January/2018, looking for publications reporting cases of OM. A total of 377 publications were included. We identified 1,692 lesions, and 695 were used for the analysis of recurrence. There is a predominance of OMs in females and in mandibles. OMs usually present with bone expansion, asymptomatic cortical perforation, and a multilocular appearance. Lesion location (maxilla/mandible), bone expansion, cortical bone perforation, locular radiological appearance, tooth resorption, odontogenic epithelial rests, or angular septa are not associated with recurrence. While curettage (31.3%) showed the highest recurrence rate, marginal resection (1.3%) and segmental resection (3.1%) showed the lowest values. Enucleation + peripheral osteotomy (6.7%) showed better results than enucleation (13.1%) or enucleation + curettage (12.7%). In comparison with unilocular lesions, multilocular ones were significantly more prevalent in mandibles, more often presented expansion and cortical bone perforation, had larger mean size, and were more often treated by segmental resection. Conservative surgical procedures are associated with higher probability of recurrence of OM. Taking into consideration the recurrence rate and morbidity associated with different surgical treatments, tumor enucleation followed by peripheral osteotomy should be considered as the first therapeutic choice.

Evaluation of the osteoclastogenic process associated with RANK / RANK-L / OPG in odontogenic myxomas

BACKGROUND

Odontogenic myxoma (OM) is a benign intraosseous neoplasm that exhibits local aggressiveness and high recurrence rates. Osteoclastogenesis is an important phenomenon in the tumor growth of maxillary neoplasms. RANK (Receptor Activator of Nuclear Factor κappa B) is the signaling receptor of RANK-L (Receptor activator of nuclear factor kappa-Β ligand) that activates the osteoclasts. OPG (osteoprotegerin) is a decoy receptor for RANK-L that inhibits pro-osteoclastogenesis. The RANK / RANKL / OPG system participates in the regulation of osteolytic activity under normal conditions, and its alteration has been associated with greater bone destruction, and also with tumor growth.

OBJECTIVES

To analyze the immunohistochemical expression of OPG, RANK and RANK-L proteins in odontogenic myxomas (OMs) and their relationship with the tumor size.

MATERIAL AND METHODS

Eighteen OMs, 4 small (<3 cm) and 14 large (> 3cm) and 18 dental follicles (DF) that were included as control were studied by means of standard immunohistochemical procedure with RANK, RANKL and OPG antibodies. For the evaluation, 5 fields (40x) of representative areas of OM and DF were selected where the expression of each antibody was determined. Descriptive and comparative statistical analyses were performed with the obtained data.

RESULTS

There are significant differences in the expression of RANK in OM samples as compared to DF (p = 0.022) and among the OMSs and OMLs (p = 0.032). Also a strong association is recognized in the expression of RANK-L and OPG in OM samples.

CONCLUSIONS

Activation of the RANK / RANK-L / OPG triad seems to be involved in the mechanisms of bone balance and destruction, as well as associated with tumor growth in odontogenic myxomas.

Odontogenic myxoma: A causality dilemma - Report of a nonpareil case and review of literature

Odontogenic myxoma is a benign locally aggressive neoplasm with a sparse prevalence and incertitude histogenesis. They constitute 3%-6% of odontogenic tumors in gnathic bones. It is ubiquitously seen between vicenarian to early quadragenarian group with female proclivity and fondness to the mandibular jaws. They are silent lesions clinically and show myxoid stroma amidst fibrous background. This report highlights central odontogenic myxoma in a 43-year-old male patient and focuses on concepts, differential diagnosis, molecular concepts and treatment aspect.

Odontogenic tumors: where are we in 2017 ?

Odontogenic tumors are a heterogeneous group of lesions of diverse clinical behavior and histopathologic types, ranging from hamartomatous lesions to malignancy. Because odontogenic tumors arise from the tissues which make our teeth, they are unique to the jaws, and by extension almost unique to dentistry. Odontogenic tumors, as in normal odontogenesis, are capable of inductive interactions between odontogenic ectomesenchyme and epithelium, and the classification of odontogenic tumors is essentially based on this interaction. The last update of these tumors was published in early 2017. According to this classification, benign odontogenic tumors are classified as follows: Epithelial, mesenchymal (ectomesenchymal), or mixed depending on which component of the tooth germ gives rise to the neoplasm. Malignant odontogenic tumors are quite rare and named similarly according to whether the epithelial or mesenchymal or both components is malignant. The goal of this review is to discuss the updated changes to odontogenic tumors and to review the more common types with clinical and radiological illustrations.

Odontogenic myxoma: A 63-year retrospective multicenter study of 85 cases in a Brazil population and a review of 999 cases from literature

BACKGROUND

Odontogenic myxoma (OM) is an uncommon neoplasm of the jaws. Considering the importance of defining the relative incidence and demographic profile of these lesions in South America, the aim of this study was to analyze the clinical and imagiological features of OM from three South American oral pathology services and to discuss these findings in light of the literature.

METHODS

Data regarding age, gender, anatomic site, and imagiological features from 85 cases of OM were collected. Additionally, we did a review of OM studies published in three electronic databases.

RESULTS

Among 63 450 oral biopsies, 1178 (1.85%) were odontogenic tumors (World Health Organization - 2017), of which 85 (7.21%) met the criteria of OM. The mean age was 30.7 years (range: 10-61 years; SD: 12.22). Forty-five (52.9%) cases occurred in females and 40 (47.1%) in males (ratio: 1:1.12). Maxilla was affected in 44 cases (53%) and mandible in 39 (47%). Of the 41 informed cases (48.2%), all of them were radiolucent lesions. The literature review indicated a majority of mean ages in third decade and a predilection for females, mandible, and multilocular radiolucent lesions.

CONCLUSIONS

The features of OM samples have strong similarity to that reported in studies from other continents. It is possible to infer that geographic variation does not help to explain some differences observed in the clinical features of OM.

Peripheral odontogenic myxoma in a 12-year-old girl: a rare entity

Peripheral odontogenic myxoma is a rare odontogenic tumor representing an extra osseous counterpart of central odontogenic myxoma. It is commonly seen in gingiva between the 3rd and 4th decades of life and appears predominantly in females. Compared to central odontogenic myxoma, it is a less aggressive, slow-growing lesion with a low recurrence rate. However, close postoperative follow-up is required because of the unlimited growth potential of incompletely removed lesions. It shares many features with other soft tissue myxoid proliferations occurring in the oral cavity and hence needs to be differentiated from them. Very few cases of peripheral odontogenic myxomas have been reported and, to the best of our knowledge, no case has been reported in a pediatric patient. We present an unusual case of peripheral odontogenic myxoma occurring in a 12-year-old girl located in the anterior mandibular gingiva, with an emphasis on differential diagnosis.

Primordial odontogenic tumor: An immunohistochemical profile

BACKGROUND

Primordial Odontogenic Tumor (POT) is a recently described odontogenic tumor characterized by a variably cellular loose fibrous tissue with areas similar to the dental papilla, covered by cuboidal to columnar epithelium that resembles the internal epithelium of the enamel organ, surrounded at least partly by a delicate fibrous capsule. The purpose of this study was to investigate the possible histogenesis and biological behavior of this rare tumor by means of a wide immunohistochemical analysis of its epithelial and mesenchymal components.

MATERIAL AND METHODS

The immunoexpression of twenty-three different antibodies were evaluated in four cases of POT.

RESULTS

The epithelial cells that cover the periphery of the tumor showed immunopositivity for Cytokeratins 14 and 19, while Amelogenin, Glut-1, MOC-31, Caveolin-1. Galectin-3, PITX2, p53, Bax, Bcl-2, Survivin and PTEN were variably expressed in focal areas. The mesenchymal component of the tumor was positive for Vimentin, Syndecan-1, PITX2, Endoglin (CD105), CD 34, Cyclin D1, Bax, Bcl-2, Survivin and p53. PTEN and CD 90 showed a moderate positivity. BRAF V600E and Calretinin were negative in all samples. Cell proliferation markers (Ki-67, MCM-7) were expressed in <5% of the tumor cells.

CONCLUSIONS

According to these immunohistochemical findings, we may conclude that POT is a benign odontogenic tumor in which there is both epithelial and mesenchymal activity during its histogenesis, as there is expression of certain components in particular zones in both tissues that suggests this tumor develops during the immature (primordial) stage of tooth development, leading to its inclusion within the group of benign mixed epithelial and mesenchymal odontogenic tumours in the current World Health Organization classification of these lesions.

Clinicopathologic analysis of 14 cases of odontogenic myxoma and review of the literature

Background

Odontogenic myxoma is a rare benign neoplasm that originates from odontogenic ectomesenchyme. There is no standard of care and recurrences are frequent after conservative surgical procedures.

Material and Methods

A retrospective study conducted at a single cancer center, with analysis of medical records of all patients diagnosed with odontogenic myxoma from 1980 to 2010, along with a literature review.

Results

There were 14 patients with diagnosis of odontogenic myxoma (OM). Most patients were female (78.6%) and Caucasian (100%), with ages ranging from 7 to 51 years (21.6 ± 11.6 years). The time period between the first symptom and first consultation ranged from 0 to 60 months (19.4 ± 19.97 months). The most frequent complaints were increased local volume or failure to tooth eruption. The most common tumor site was the mandible (11 cases, 78.5%). About radiological findings, most lesions were multilocular (9 cases, 64.3%) and with imprecise limits (12 cases, 85.7%). Surgery was performed in all cases and curettage was the most applied technique (10 cases, 71.4%). Three patients underwent mandibulectomy and complex reconstructions including iliac crest microvascular flap. Three patients had postoperative complications and 4 had local recurrences of the tumor. The follow up time ranged from 12 to 216 months (112 ± 70.8 months). All patients are without clinical and radiographic evidence of disease.

Conclusions

OM is a locally aggressive and rare tumor. There is no gold standard surgical management and the therapeutic decision should be individualized taking into account the characteristics and extension of the tumor.

Key words:Mandible, myxoma, odontogenic, odontogenic tumor.

Odontogenic myxoma: A review with report of an uncommon case with recurrence in the mandible of a teenage male

We describe a 13-year-old boy with recurrence of an odontogenic myxoma of the mandible. We review the existing published literature on the lesion, emphasizing the similarities and differences among lesions in the differential diagnosis. Odontogenic myxoma is an uncommon benign tumor that mainly affects the mandible, with a peak incidence in the second to fourth decades of life and predilection for the female sex. Clinical, radiological, and histopathological features should be considered when making a diagnosis. Several of these characteristics overlap with those of other benign and some malignant tumors. Odontogenic myxoma is known for recurrence. The treatment plan should consider the age and sex of the patient and the site and size of the lesion. Reconstructive surgery may be required, but should be delayed until after an adequate follow-up to rule out recurrence.

Odontogenic Cysts and Neoplasms

This article reviews a myriad of common and uncommon odontogenic cysts and tumors. The clinical presentation, gross and microscopic features, differential diagnosis, prognosis, and diagnostic pitfalls are addressed for inflammatory cysts (periapical cyst, mandibular infected buccal cyst/paradental cyst), developmental cysts (dentigerous, lateral periodontal, glandular odontogenic, orthokeratinized odontogenic cyst), benign tumors (keratocystic odontogenic tumor, ameloblastoma, adenomatoid odontogenic tumor, calcifying epithelial odontogenic tumor, ameloblastic fibroma and fibroodontoma, odontoma, squamous odontogenic tumor, calcifying cystic odontogenic tumor, primordial odontogenic tumor, central odontogenic fibroma, and odontogenic myxomas), and malignant tumors (clear cell odontogenic carcinoma, ameloblastic carcinoma, ameloblastic fibrosarcoma).

Myofibroblasts and mast cells: influences on biological behavior of odontogenic lesions

Odontogenic lesions differ in their rate of recurrence and aggressiveness. This study aimed to evaluate the presence of myofibroblasts and mast cells in odontogenic lesions. Sample consisted of 20 cases each of dentigerous cysts, odontogenic keratocysts, and solid ameloblastomas. Histologic sections were submitted to immunohistochemistry using anti-α-smooth muscle actin and anti-tryptase antibodies. Myofibroblasts and mast cells were counted at ×400 magnification in 5 and 10 fields, respectively. Myofibroblasts were more frequent in ameloblastomas (24.41), followed by odontogenic keratocysts (16.21) and dentigerous cysts (11.85; P=.002). Granulated and degranulated mast cells were more frequent in dentigerous cysts (7.88 and 8.96, respectively), followed by odontogenic keratocysts (6.53 and 7.08) and ameloblastomas (5.21 and 1.88). The difference was only significant for degranulated mast cells (P<.05). Analysis of the correlation between myofibroblasts and mast cells (granulated and degranulated) revealed a moderate positive correlation only in ameloblastomas (R=0.621, P=.003). Probably, myofibroblasts are related to the biological behavior of the odontogenic lesions studied, particularly their aggressiveness. On the other hand, mast cells seem to be associated with inflammatory processes, which are more frequent in cystic lesions than in benign neoplasms. In addition, mast cells may induce the differentiation of fibroblasts into myofibroblasts, thus increasing the number of the latter.

Assessment of CD-105 as an Angiogenic Modulator in Odontogenic Myxomas and Dental Follicles

Aim Odontogenic myxoma is a benign intraosseous neoplasm of the jaws, with a locally aggressive behavior and a high recurrence rate. CD-105 is a homodimeric cell membrane glycoprotein and is a component of the TGF-β1 growth factor receptor complex that modulates angiogenesis by regulating the proliferation, differentiation and cellular migration. The aim of this study is to quantify the microvascular density of the odontogenic myxoma based on the expression of CD-105. Materials and Methods The analysis included 18 odontogenic myxoma and 18 dental follicles as controls. A standard immunohistochemical procedure was performed with the CD-105 antibody. Five representative fields (40×) of the odontogenic myxoma and the dental follicles were selected to determine the microvascular density, which was then followed by a descriptive and comparative statistical analysis. Results Dental follicles presented a significantly higher microvascular density compared with odontogenic myxoma (P = .001). The odontogenic myxoma smaller than 3 cm showed a greater microvascular density than those larger than 3 cm in size (P > .05), and the microvascular density was lower in large odontogenic myxomas as compared with the dental follicles (P = .003). Conclusion A weaker expression of CD-105 in odontogenic myxoma might indicate a lower angiogenic activity, suggesting that vascular proliferation has a limited role in the growth mechanisms and in the aggressive behavior of this neoplasm.

Novel Association of Odontogenic Myxoma with Constitutional Chromosomal 1q21 Microduplication: Case Report and Review of the Literature

Odontogenic myxoma (OM) is a rare, benign, and locally aggressive tumor. It tends to occur in the posterior maxilla and mandible and is often associated with root resorption and perforation of cortex. Histopathologically, there is a proliferation of spindle, bipolar, and stellate cells, with bland nuclei within a myxoid to infrequently fibromyxoid extracellular matrix. Long, thin residual bony trabeculae are often seen floating within the spindle cell proliferation because of the infiltrating nature of this tumor, and these trabeculae impart a "soap bubble" or "tennis-racket" radiologic appearance. No syndromic association of OM has been reported. Although similar histopathologic features are shared with cardiac myxoma and soft tissue myxoma, mutations in the GNAS gene have not been identified in OM to date, and only 2 of 17 OMs showed mutations in the PRKAR1A gene. In this report, we describe a case of OM in a patient with constitutional 1q21 microduplication, a locus that harbors genes encoding certain proteins in the cAMP-dependent protein kinase A (PKA) signaling pathway, including G-protein-coupled receptors and 1 phosphodiesterase interacting protein. Review of the literature describes the key clinical features and molecular pathogenesis of 1q21 microduplication, as well as highlighting the role of PKA signaling pathway in the pathogenesis of myxomas in general.

Odontogenic myxoma: a clinicopathological study in a South African population

BACKGROUND

Odontogenic myxoma is a benign, locally aggressive neoplasm of the jaws. Prevalence rates range between 0.5% and 17.7% of odontogenic tumours. There are few reports in the literature on this lesion in African populations, and therefore, this study aimed to report on odontogenic myxoma in a South African population over a 40-year period.

METHODS

The clinical records and orthopantomograms of 29 histopathologically diagnosed odontogenic myxoma were retrospectively analysed. Details of age, gender, ethnic origin and clinical, histological as well as radiological features were recorded.

RESULTS

The ages of patients ranged from 7 to 44 years with a mean of 21.3 years. The male-to-female ratio was 1:2.6 with the majority of patients being of mixed race and Africans. Clinically, 31% complained of pain while 58.6% had a history of swelling. The majority of odongenic myxomas (62.1%) were located in the mandible with the posterior region being most commonly affected. Multilocular lesions (69.2%) were more common and were significantly larger than unilocular lesions (P < 0.05). The outline of these tumours was mostly well-defined (84.6%) with different degrees of cortication. Only one tumour caused tooth resorption, while 20 cases (76.9%) caused tooth displacement. Six tumours expanded into the maxillary sinus, and 14 tumours caused expansion of the mandible.

CONCLUSIONS

Odontogenic myxomas have variable clinical, radiological and histological features. Most of these features in this population were similar to other populations. It is mandatory to use conventional radiographs along with histopathological examination to aid in arriving at an accurate diagnosis.

An aggressive odontogenic myxoma of the maxilla

Odontogenic myxoma (OM) is a relatively rare benign odontogenic tumor of mesenchymal origin. OM is more common in the mandible than in the maxilla. It is an asymptomatic lesion that shows an infiltrative growth pattern. When the maxillary sinus is involved, it often fills the entire antrum. Odontogenic tumors are uncommon in the maxillary molar area, which often leads to diagnostic dilemma as this region of the maxilla is in the vicinity of vital structures, and radiographic overlapping of structures is always present. We present a similar case of a 17-year-old male patient who reported with a swelling in the left maxilla that infiltrated the maxillary sinus in a short duration of time.

Ameloblastic fibroma: A rare case appearing as a mixed radiographic image

Ameloblastic fibroma (AF) is a benign tumor of mixed odontogenic origin, which affects predominantly young individuals. AF appearing as a mixed radiographic image is very rare. This report describes a case of AF in a 12-year-old male identified during a routine radiographic exam for orthodontic treatment planning. The panoramic radiography revealed a well-defined multilocular mixed image located in the mandible between the roots of the left mandibular second premolar and first molar. The lesion was excised under local anesthesia. Histopathological analysis revealed islands of epithelial cells and columnar peripheral cells showing a nucleus in inverted polarization, interspersed with spindle-shaped cells and abundant extracellular matrix deposition. No atypia was observed. The diagnosis of AF was established. No tumor recurred up to 30 months after treatment. Although rare, AF should be also considered in the differential diagnosis of mixed radiographic images of the jaws in young patients.

Key words:Ameloblastic fibroma, differential diagnosis, incidental finding, mixed image, radiographic features.

The diagnostic usefulness of immunohistochemistry for odontogenic lesions

The diagnosis of odontogenic tumors can be challenging, largely due to their rarity and consequent difficulties in gaining experience in their assessment. In most cases, careful attention to morphology, in conjunction with clinical and radiological features will allow a diagnosis to be made. However, in some cases, immunohistochemical analysis of the tumor may be useful. In this review we will outline the immunohistochemical expression profile of normal developing odontogenic tissues and a range of odontogenic tumors. In many cases the immunohistochemical markers are neither specific nor sensitive enough to be of help in diagnosis, but in some cases such analysis may prove very useful. Thus we have outlined a limited number of circumstances where immunohistochemistry may be of use to the practicing diagnostic pathologist.

Multiple fibromyxomas of the jaws: A case report

Fibromyxoma of the jaw is a rare benign mesenchymal odontogenic tumor with locally aggressive behavior. In the present report, a 13-year-old female patient presented to our university hospital with delayed eruption of some of her teeth. A panoramic radiograph taken at the initial examination revealed four pericoronal radiolucencies related to the four third molars. Thereafter, a magnetic resonance imaging (MRI) examination was performed. After the surgical removal of these molars, the microscopic examination diagnosed the four lesions as fibromyxomas. Here, we have discussed the clinical, panoramic radiography, MRI, and histopathological findings of the case.

Primordial odontogenic tumour: clinicopathological analysis of six cases of a previously undescribed entity

AIM

To describe the clinicopathological and immuno-histochemical features of six tumours that do not fulfil the criteria of any of the currently classified odontogenic tumours.

METHODS AND RESULTS

The patients were three males and three females, whose ages ranged from 3 years to 18 years (mean, 11.05 years). In all cases there were well-defined radiolucencies associated with unerupted teeth apparently showing a pericoronal relationship. Microscopically, all tumours were composed of variably cellular loose fibrous tissue with areas similar to dental papilla, entirely surrounded by cuboidal to columnar epithelium resembling the internal epithelium of the enamel organ. Mesenchymal tissue was positive only for vimentin, and Ki67 expression was very low (<2%). The epithelium was positive for CK AE1/AE3, CK5, CK14, and CK19, but negative for CK18 and CK20. All cases showed clear demarcation from the surrounding bone, and were surgically removed, with no recurrences after follow-up ranging from 6 months to 20 years.

CONCLUSIONS

These findings differ from those observed in other odontogenic lesions, such as ameloblastic fibroma, odontogenic myxoma, odontogenic fibroma, and hyperplastic dental follicles. The term primordial odontogenic tumour is proposed to describe this novel lesion.

Myofibroblasts in oral lesions: A review

Myofibroblasts (MFs) are modified fibroblasts that express features of smooth muscle differentiation and were first observed in granulation tissue during wound healing. These cells play a key role in physiologic and pathologic processes like wound healing and tumorigenesis. The presence of MFs has been reported in normal oral tissues and pathologic conditions like reactive lesions, benign tumors, locally aggressive tumors and malignancies affecting the oral cavity. This article briefly reviews the important hallmarks related to the discovery, characterization and tissue distribution of MFs in oral health and disease.