Malignant ameloblastoma revisited

FDG-PET findings of Ameloblastoma: a case report

Introduction

Ameloblastoma is a benign odontogenic neoplasm of the jaw, rarely presenting as a malignant tumor. Although it is very important to discriminate ameloblastoma from ameloblastic carcinoma in order to decide the appropriate operative procedure, this is difficult using conventional CT and MRI.

Case descriptions

We report a case of maxillar ameloblastoma in a 78-year-old man where FDG-PET/CT was useful for making this discrimination. CT demonstrated a 31 × 43 × 46-mm mass in the left posterior maxillary sinus with destruction of its posterior and lateral wall and alveolar bone. MRI demonstrated a hypo- to isointense heterogeneous pattern on T1WI, heterogeneous hyperintensity with a prominent high-signal spot on T2WI, high signal intensity on DWI reflecting restricted diffusion, and strong heterogeneous enhancement. Because FDG-PET/CT showed mild FDG uptake (SUVmax 2.40) by the mass, ameloblastoma, rather than ameloblastic carcinoma, was considered to be the correct diagnosis.

Discussion and evaluation

It appears that ameloblastic carcinoma shows intense FDG uptake, whereas ameloblastoma shows mild or moderate FDG uptake, and only rarely intense FDG uptake. Our experience suggests that FDG-PET/CT may be effective for discriminating ameloblastoma from ameloblastic carcinoma. Especially, in cases showing mild FDG uptake, benign ameloblastoma would seem the most likely diagnosis.

Conclusions

FDG-PET/CT may be useful as an adjunctive modality for diagnosis, treatment planning and surveillance of ameloblastoma and ameloblastic carcinoma.

Ameloblastic carcinoma: A case series

Ameloblastic carcinoma is a rare odontogenic tumor exhibiting not only features of ameloblastoma, but also features of carcinoma. Clinical dissemination of this lesion is more aggressive and rapid than that of ameloblastoma and it can metastasize to the lung or regional lymph node. Histologically, there are features of both ameloblastoma and carcinoma. <50 cases have been reported until 2011. We report a series of six cases with our treatment modalities.

Malignant ameloblastoma: concurrent presentation of primary and distant disease and review of the literature

Malignant ameloblastoma is a rare tumor of odontogenic origin with a metastatic focus. Distant metastatic disease is found most commonly in the lungs. A review of the literature shows that most cases of malignant ameloblastoma involve a disease-free period from primary tumor extirpation to the discovery of metastasis. This report describes the case of a 56-year-old man presenting with ameloblastoma of the maxilla and a solitary pulmonary metastasis concurrently. This represents a rare case in which there is a simultaneous diagnosis of primary ameloblastoma and a metastatic lesion. Appropriate workup for ameloblastoma includes surveillance for metastatic disease. Surgical resection of primary and distant disease is recommended. Chemotherapy and radiation may play a role in palliation when resection of metastatic disease is not feasible.

Ameloblastic carcinoma: a case report with radiological features of computed tomography and magnetic resonance imaging and positron emission tomography

Ameloblastic carcinoma is a rare malignant odontogenic carcinoma that has metastatic potential, and because of its rare incidence, there are few reports focusing on its radiologic imaging. If it shows aggressive appearances, it can be diagnosed as malignant tumor. But in case of negative appearance, it is difficult to distinguish ameloblastic carcinoma from ameloblastoma. We report a case of ameloblastic carcinoma of the maxilla in a 76-year-old female patient with radiologic images and pathologic features.

Ameloblastic carcinoma of the mandible with metastasis to the skull and lung: advanced imaging appearance including computed tomography, magnetic resonance imaging and positron emission tomography computed tomography

Ameloblastic carcinoma is a very rare malignant odontogenic tumour with characteristic histopathological and clinical features, which requires aggressive surgical treatment and surveillance and, therefore, differs from ameloblastoma. Metastasis typically occurs in the lung. Only one patient with metastasis to the skull has previously been described and no prior case reports have presented MRI and positron emission tomography-CT (PET-CT) imaging findings. We describe a case of ameloblastic carcinoma with metastasis to the skull and lung with emphasis on imaging features including MRI and PET-CT.

A multirecurrent ameloblastoma metastatic to the lung

INTRODUCTION

The ameloblastoma is a rare tumor of odontogenic epithelial origin. It is a neoplasm in which ameloblastic features are revealed by the primary growth in jaws and by any metastatic growth. Recurrences are usually local and distant metastases are rare. We present a case of a multirecurrent ameloblastoma of the mandible metastatic to the lung.

OBSERVATION

We present a case of a mandibular malignant ameloblastoma in a 42-year old man with widespread pulmonary metastases. Some of these lesions were treated surgically.

DISCUSSION

Ameloblastoma metastasis often occurs in the lung. The curative treatment is surgical. The results of palliative chemotherapy and radiotherapy are not always efficient.

Critical role of heparin binding domains of ameloblastin for dental epithelium cell adhesion and ameloblastoma proliferation

AMBN (ameloblastin) is an enamel matrix protein that regulates cell adhesion, proliferation, and differentiation of ameloblasts. In AMBN-deficient mice, ameloblasts are detached from the enamel matrix, continue to proliferate, and form a multiple cell layer; often, odontogenic tumors develop in the maxilla with age. However, the mechanism of AMBN functions in these biological processes remains unclear. By using recombinant AMBN proteins, we found that AMBN had heparin binding domains at the C-terminal half and that these domains were critical for AMBN binding to dental epithelial cells. Overexpression of full-length AMBN protein inhibited proliferation of human ameloblastoma AM-1 cells, but overexpression of heparin binding domain-deficient AMBN protein had no inhibitory effect. In full-length AMBN-overexpressing AM-1 cells, the expression of Msx2, which is involved in the dental epithelial progenitor phenotype, was decreased, whereas the expression of cell proliferation inhibitors p21 and p27 was increased. We also found that the expression of enamelin, a marker of differentiated ameloblasts, was induced, suggesting that AMBN promotes odontogenic tumor differentiation. Thus, our results suggest that AMBN promotes cell binding through the heparin binding sites and plays an important role in preventing odontogenic tumor development by suppressing cell proliferation and maintaining differentiation phenotype through Msx2, p21, and p27.

Can Radiofrequency Ablation Be Used as a Treatment Modality for the Management of Pulmonary Metastatic Ameloblastoma?

We report the case of a 59-year-old woman who presented with metastatic ameloblastoma involving the lungs, 20 years after resection of the primary tumor in the mandible. The lesions were debulked on multiple occasions with radiofrequency ablation over an eight-year period with local response. There were no complications related to the procedures. We suggest that radiofrequency ablation is a possible treatment modality for the management and control of metastatic ameloblastoma.

Malignant ameloblastoma metastasis to the lung: a case report

Ameloblastoma is an odontogenic tumor, usually benign, which rarely metastasizes to distant organs. The case of a 27-year-old white woman is described, who presented a metastatic pulmonary ameloblastoma 7 years after the removal of a mandibular ameloblastoma. She presented no pulmonary symptoms, but a lung nodule was found in a chest x-ray during a routine check-up for job admission. Computed tomography (CT) revealed a 2-cm well-defined solitary round nodule without calcifications, leading to the hypothesis of a metastatic tumor. Clinical and CT investigation confirmed no ameloblastoma recurrence in the jaw and no other primary tumor. The diagnosis of metastatic ameloblastoma was confirmed by microscopic evaluation of the pulmonary nodule.

Malignant ameloblastoma metastatic to the lungs 29 years after primary resection: a case report

We describe a case of a 55-year-old man presenting with a metastatic malignant ameloblastoma 29 years after the primary tumor was resected. This represents the longest period between initial diagnosis and first subsequent metastasis recorded as a case report. This case illustrates distinctions between the terms metastatic and malignant; it also highlights the difficulties derived from the accumulation of data by new diagnostic modalities (electron beam CT and positron emission tomography) and their integration into assessment algorithms.

Pulmonary metastasis of ameloblastoma: case report and review of the literature

Ameloblastomas are benign tumors of odontogenic epithelial origin. There is a high incidence of local recurrence associated with these tumors, and distant metastasis is rare. A review of the English literature shows that there have been 41 prior reports of pulmonary metastases from ameloblastomas of the oral cavity. We present another case of ameloblastoma metastatic to the lung and review the histopathology and mechanism of metastatic spread.

Ameloblastic carcinoma of the mandible

BACKGROUND

Ameloblastic carcinoma is a rare, aggressive odontogenic neoplasm of the jaws in which the epithelial cells exhibit cytologic features of recognizable ameloblastoma and malignancy. Cases with metastasis have been infrequently reported.

METHODS

A case of a 64-year-old white woman with mandibular ameloblastic carcinoma with documented distant metastasis is presented. The patient's presenting symptoms included facial asymmetry of the right jaw over 2 months and the development of moderate trismus. Clinical manifestations, pathology, treatment, and biologic behavior are discussed. The nomenclature and classification of odontogenic carcinomas are reviewed, including entities that should be considered in the differential diagnosis.

RESULTS

The patient underwent surgical resection consisting of mandibulectomy, parotidectomy, and modified radical neck dissection followed by radiation to both necks and tumor bed. Postsurgically, the patient developed pulmonary metastasis at 11 months and expired with widespread metastatic disease at 28 months.

CONCLUSIONS

This case demonstrated an unusual behavior pattern in that local recurrence and regional metastasis did not occur. Distant metastasis occurred despite apparent adequate control of the primary mandibular tumor. The ameloblastic carcinoma is a highly malignant neoplasm which requires aggressive therapy. Prognosis is poor. Further reporting of ameloblastic carcinoma is encouraged.

Diagnostic imaging in two cases of recurrent maxillary ameloblastoma: comparative evaluation of plain radiographs, CT and MR images

We report detailed clinical and imaging findings of two patients with recurrent maxillary ameloblastoma. In one patient the recurrent tumour presented at follow-up examination 5 years after the initial operation. The other patients had a far advanced recurrent tumour with maxillary destruction extending into the adjacent normal structures including the infratemporal fossa, infraorbital fissure, masticator space and the left ethmoid sinus. The findings on conventional radiography including panoramic, posteroanterior and Waters' projection, and the findings of computed tomography (CT) and magnetic resonance (MR) imaging were evaluated using the following three variables: artefact degradation, lesion detectability, and conspicuity. The results suggested that MR imaging was the best imaging method for visualization of the tumours, followed by contrast enhanced CT. These two cases show that maxillary ameloblastoma can be difficult to control when it extends to the adjacent normal structures after destroying the maxilla. MR imaging was essential to establish the exact extent of the advanced maxillary ameloblastoma.

Intraosseous carcinoma arising from mandibular ameloblastoma with progressive invasion and pulmonary metastasis

A 60-year-old woman, who had undergone curettage of a mandibular ameloblastoma about 20 years before, presented with recurrence of an ameloblastoma in the mandibular symphysis. This tumor was removed by a marginal resection. About 2 years later, the tumor recurred in the right mandibular ramus, and the patient underwent right mandibulectomy. About 6 months later, the tumor again recurred. Radical resection was performed, but invasion of the infraorbital region and cranial base was noted. An anterior craniotomy was then performed and the lesion removed. Histologically, proliferation of squamous cells associated with atypia was seen, and ameloblastic features were no longer observed. Metastasis to the lung was noted 1 year later.