Introduction: Surface osteosarcomas represent around 3-6% of all osteosarcomas, which include the parosteal (low-grade), periosteal (intermediate-grade) and high-grade surface osteosarcomas. The classical location is the femur, followed by tibia and humerus. Parosteal osteosarcoma is the most common type of surface osteosarcoma. To date, 26 cases of parosteal osteosarcoma affecting the jaws have been reported, with most cases following an evolution time of several months to years, clinically favoring a benign osseous or fibro-osseous lesion. Methods: Here, we report a 39-year-old female who was referred presenting a maxillary tumoral mass 5 years ago, clinically diagnosed as osteoma. After clinical, imaginological and histopathological analysis, a diagnosis of parosteal osteosarcoma was made. Conclusion: Thus, parosteal osteosarcoma should also be considered in the differential diagnosis of benign-appearance, bone-forming nodular lesions affecting the jaws.

BACKGROUND: Osteosarcomas of the jaws are very rare accounting for only 6 to 7% of all osteosarcomas and 1% of all head and neck malignancies. The clinicopathological characteristics as well as the radiological characteristics are not specific, which represents a diagnostic dilemma. Indeed, this lesion is often mistaken for benign lesions of the maxillary.
METHODS: We report a case of osteosarcoma of the jaws in a 45 year man who consulted in our service for a simple painless oral swelling evolving since a five months. The lesion was excised and histopathological report confirmed the diagnosis of osteosarcoma of the jaw.
CONCLUSIONS: Osteosarcomas are a rarely progressive tumor in the oral cavity that can show up as a case of a benign process of dental origin. During our practice, we often meet similar cases which are treated by usual medication, while a whole malignant process is in the progress and can be life-threatening. The case we present illustrates this perfectly, and owing to a deep clinical investment, the malignant process was stopped at its start.
CONCLUSIONS: The objective of presenting this case is to draw the attention of the doctors that any lesions even of benign appearance can hide a malignant process. Consider this point and integrate it into its diagnostic approach should be undertaken and should lead to a deepening of the clinical examination by comparing the clinical, radiological and histological data.

This report intends to compare classic presentations of odontogenic myxoma in contrast to our case. We also suggest a comprehensive evaluation of lesions and strongly advocate against premature treatments before reaching a definitive diagnosis.

Myofibroma (MF) is a benign mesenchymal myofibroblast-derived tumor, which occurs most frequently in children, and rarely affects the maxilla. We reported a case of an aggressive intraosseous lesion found in the maxilla of a 9-year-old female child. Intraorally, the swelling extended from tooth 12 to 16, causing displacement of teeth 13, 14, and 15. Computed tomography revealed a large osteolytic lesion causing thinning and cortical erosion. Microscopically, the lesion showed a proliferation of spindle-shaped cells, with elongated nuclei and eosinophilic cytoplasm, arranged in interlaced fascicles. The immunohistochemical analysis revealed cytoplasmic positivity for α-SMA and HHF-35, and negativity for desmin, laminin, S-100, β-catenin, and CD34. Ki-67 was positive in 8% of tumor cells. The diagnosis was MF. Herein, we describe an additional case of central MF arising in the maxilla, including clinical, imaging, microscopical, and immunohistochemical features, as well as a review of the literature.

Proteus syndrome (PS) is an extremely rare disorder with asymmetric and disproportionate bone overgrowth. Craniofacial abnormalities in PS are less frequent than skeletal abnormalities. Although there are recognized oral and maxillofacial manifestations of PS, few case reports describing these manifestations are available. Thus, the objective of this systematic review and case report is to describe oral and maxillofacial manifestations of PS and to report a PS case.
A 31-year-old male presented with restricted mouth opening and pain during mastication. A panoramic radiograph and an occlusal radiograph were obtained. Reports with relevant keywords were assessed. Data were summarized and demonstrated using a critical appraisal checklist for case reports.
The panoramic radiograph demonstrated unilateral overgrowth of the mandible, impacted teeth, and deciduous prolonged retention. Thirteen PS case reports were identified.
Proteus syndrome oral and maxillofacial manifestations may include dental agenesis, impacted teeth, malocclusion, asymmetric dental growth and maturation, frontal line displacement, asymmetric tongue enlargement, mandibular hemihypertrophy and asymmetry, presence of exostoses/hyperostosis, degenerative changes in the temporomandibular joint, alterations of maxillary and mandibular vertical and/or horizontal growth, and enlargement of mandibular canal and foramen. The PROSPERO systematic review registration number is CRD42019140942.

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) was first mentioned in the literature in 2003. Since then, several reports have been published referring to this disease. The etiology of BRONJ still remains unclear. The treatment of BRONJ also remains a topic of discussion between those who are in favor of a conservative treatment and those who are convinced that surgical treatment gives the best results. In this case report, a patient is presented with BRONJ in the mandible which has been treated surgically in combination with antibiotic treatment. During surgery it appeared that a large part of the jaw was sequestrated full-thickness with, at the same time, formation of a substantial amount of subperiosteal bone that was formed around the BRONJ, supporting the sequestrated part of the mandible and, after sequestrectomy, serving as a neo-mandible. This case shows the capacity of the jawbone despite bisphosphonate use to regenerate itself.

Aneurysmal bone cyst (ABC) is an uncommon, non-neoplastic, expansive and erosive bone lesion. Considered as a pseudocyst due the lack of epithelial lining, the presence of giant cells and similarity to other lesions can make preoperative diagnosis difficult; biopsy findings must be co-related to complete clinical and radiological assessment. ABC\'s controversial etiopathogenesis and variable clinicopathological presentations have been widely described, but to date, there are just a few reports in literature describing the development of fibrous dysplasia (FD) from an ABC, and even less cases occurring in the jaws. We describe the case of an ABC in an 8 year-old male patient, affecting the body of the mandible, which showed accelerated growth associated to thinning of the buccal, lingual and lower cortical plates. The treatment consisted of repetitive surgical resection, curettage of the lesion and mandibular reinforcement with osteosynthesis reconstruction plates. A 16-month follow-up showed self-limitation of the overgrowth. The final histopathological and radiological analysis confirmed the FD diagnosis.

Epithelioid osteosarcoma is an uncommon variant; only 4 cases have been reported in the jaw area, 2 of which were in the maxilla. A 22-year-old woman, in the eighth month of pregnancy, presented to the oral surgery clinic with a mass in the right maxilla that had rapidly expanded over the past 3 months. Computed tomography scans showed an ill-defined sclerotic destructive lesion that formed bone matrix in its soft tissue extension. Microscopic examination of the lesion revealed malignant epithelioid cells with osteoid deposits. The tumor cells were shown to have pale cytoplasm, vesicular nuclei, and prominent nucleoli and to undergo frequent mitosis. In addition, the tumor was positive for epithelial membrane antigen and vimentin and negative for AE1/AE3, Melan-A, CD30, synaptophysin, NSE, CD45, CD99, desmin, and myogenin. The final diagnosis was epithelioid osteosarcoma, which is a rare aggressive variant of osteosarcoma. Few cases of epithelioid osteosarcoma have been reported in the literature, and more studies are required to determine the clinical behavior of this tumor.

The introduction of bisphosphonates has increased in the last decade following their indication for metastatic bone diseases, osteoporosis, hypercalcaemia of malignancy and Paget\'s disease. Although bisphosphonates have been used clinically for more than three decades there have been no documented long-term complications of their effects on the jaws until recently, where there is now growing evidence of the influence of bisphosphonates on osteonecrosis of the jaws. The aim of this paper is to report a case of this newly described complication, to review this phenomenon, including the clinical implications and to reiterate current clinical guidelines for management of patients in which bisphosphonate therapy is indicated. To the best of our knowledge this is the first reported case of bisphosphonate-induced necrosis of the jaw in South Africa.

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