Ameloblastic carcinoma, secondary type: a case report

Malignant variants of ameloblastoma include metastasizing ameloblastoma, which microscopically appears benign but has metastasized and ameloblastic carcinoma that exhibits malignant histopathologic features. Ameloblastic carcinoma is classified into 2 types: a primary odontogenic malignancy and a secondary type resulting from malignant transformation of ameloblastoma. Most secondary ameloblastic carcinomas result from malignant transformation of a primary lesion after repeated postsurgical recurrences. Therefore it is rare to find an untreated secondary type presenting with histologic features of malignant transformation from an earlier benign lesion. We experienced a rare case of ameloblastic carcinoma, secondary type which might arise in an untreated ameloblastoma. The mechanism by which a preexisting benign ameloblastoma goes through a malignant transformation is also described.     

Ameloblastic Carcinoma of the mandible

Odontogenic carcinomas are rare lesions arising from dental embryogenic residues and have been designated by a variety of terms like malignant ameloblastoma, ameloblastic carcinoma, metastatic ameloblastoma or primary intra-alveolar epidermoid carcinoma. Ameloblastic carcinoma combines the histological features of ameloblastoma with cytological atypia, even in the absence of metastasis. The lesion has been reported to arise either from the odontogenic cyst or the ameloblastoma. Majority originate de novo and the remaining are malignant transformation of an ameloblastoma.     

Ameloblastic carcinoma ex ameloblastoma of the mandible with malignancy-associated hypercalcemia

Ameloblastoma is a rare, locally destructive, benign neoplasm of the jawbones, which arises from epithelium derived from the epithelial components of the developing tooth. Ameloblastic carcinoma is the term used to designate any ameloblastoma in which there is histologic evidence of malignancy in the primary tumor, regardless of whether it has metastasized. Most ameloblastic carcinomas are presumed to have arisen de novo, with few cases of malignant transformation of ameloblastoma being apparent. Hypercalcemia is the most common metabolic complication of malignancy. Although malignancy-associated hypercalcemia is often reported in association with other malignancies, it is exceedingly unusual in association with ameloblastoma, malignant ameloblastoma, or ameloblastic carcinoma. We describe a patient with multiple recurrences of ameloblastoma, with subsequent malignant transformation presenting with malignancy-associated hypercalcemia.     

Ameloblastic carcinoma: a clinicopathologic study and assessment of eight cases

The term ameloblastic carcinoma is differentiated from the term malignant ameloblastoma and is defined as an ameloblastoma in which there is histologic evidence of malignancy in the primary tumor or the recurrent tumor (or metastasis), regardless of whether it has metastasized. Eight cases of ameloblastic carcinoma from the Armed Forces Institute of Pathology (AFIP) are reported. The mean age of patients was 30.1 years, with no sex predilection noted. Seven cases involved the mandible and one involved the maxilla, with the posterior regions favored. The most common sign was swelling, although pain, rapid growth, trismus, and dysphonia also occurred. Lesions characteristically were evident as ill-defined destructive radiolucencies, with occasional radiopacities noted. Histologic features generally resembled those of conventional ameloblastoma but with cytologic features of epithelial malignant disease. The clinical course was uniformly aggressive with extensive local destruction and spread, frequent recurrences, and one case of neck node metastasis. The nomenclature and classification of odontogenic carcinomas are discussed, as well as entities that should be included in the differential diagnosis. Further reporting of ameloblastic carcinoma is encouraged.     

Malignant ameloblastoma or ameloblastic carcinoma

The World Health Organization defines malignant ameloblastoma as a lesion exhibiting features of an ameloblastoma in primary and metastatic growths. To cases collected from the literature we have added two of our own cases in which features of an ameloblastoma were coupled with malignant behavior. It was noted that the diagnosis of “malignant ameloblastoma” is at present used in a rather indiscriminate way, resulting in the grouping of lesions that exhibit considerable differences in biological behavior and histomorphology. This might be due to the fact that the WHO classification emphasizes metastasis as a diagnostic criterion but is rather vague in defining histopathologic aspects. It is advocated that the term malignant ameloblastoma be reserved for those lesions that, in spite of a seemingly innocuous histology, have given origin to metastatic growths, while the WHO classification should be modified to include ameloblastic carcinoma as a diagnostic term for lesions that combine features of an ameloblastoma with a less-differentiated histomorphology.     

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 maxilla. A case report

A case of an ameloblastic carcinoma in an unusual situation in the maxilla is presented. The lesion is characterized histologically by areas with features of a typical ameloblastoma and areas with anaplastic transformation. A Caldwell-Luc operation was followed by a recurrence after 3 years. Due to the advanced age and poor general health of the patient an enlarged, but not radical operation was performed. There is no evidence of metastatic tumour.     

Ameloblastoma and its relationship to ameloblastic fibroma: their histogenesis based on an unusual case and review of the literature.

The present paper describes the relationship between ameloblastoma and ameloblastic fibroma deduced from a case diagnosed as "ameloblastoma combined with ameloblastic fibroma" arising in the mandible of a 5-year-old boy. Histologically, the tumor consisted of ameloblastoma in the central area and ameloblastic fibroma in the peripheral area; it clinically fits the characteristics of ameloblastic fibroma based on predominant age, manner of growth, and encapsulation. We reviewed the literature and discussed the relationship between ameloblastoma a ameloblastic fibroma in terms of tumorigenesis. It is assumed that ameloblastic fibroma can also be transformed into ameloblastoma, if the succeeding hard tissues are not formed, and the collagenous connective tissue substituting for the stromal mesenchymal tissue is formed by the inductive effect of the epithelial strands or other unknown factors. Several possibilities relative to the pathogenesis of ameloblastoma have been proposed by oral pathologists; however, to our knowledge, "ameloblastic fibroma can be transformed into ameloblastoma" has not hitherto been reported. The case we experienced here may be thought as an intermediate tumor pattern between ameloblastic fibroma and ameloblastoma.     

Ameloblastic carcinoma: case report and literature review

Ameloblastic carcinoma is a rare malignant lesion with characteristic histologic features and behaviour that dictates a more aggressive surgical approach than that of a simple ameloblastoma. However, reliable evidence of its biologic activity is currently unavailable due to the scarcity of well-documented cases. It occurs primarily in the mandible in a wide range of age groups; no sex or race predilection has been noted. It may present as a cystic lesion with benign clinical features or as a large tissue mass with ulceration, significant bone resorption and tooth mobility. Because the lesion is usually found unexpectedly after an incisional biopsy or the removal of a cyst, a guide to differential diagnosis is not usually useful. The identifying features of ameloblastic carcinoma must be known and recognized by dental practitioners. Our understanding of the histologic features of ameloblastic carcinoma is somewhat vague. The tumour cells resemble the cells seen in ameloblastoma, but they show cytologic atypia. Moreover, they lack the characteristic arrangement seen in ameloblastoma. The clinical course of ameloblastic carcinoma is typically aggressive, with extensive local destruction. Direct extension of the tumour, lymph node involvement and metastasis to various sites (frequently the lung) have been reported. Wide local excision is the treatment of choice. Regional lymph node dissection should be considered and performed selectively. Radiotherapy and chemotherapy seem to be of limited value for the treatment of ameloblastic carcinomas. At the moment, there are too few reported cases to make a definite recommendation regarding treatment. Close periodic reassessment of the patient is mandatory.     

Ameloblastic carcinoma of the mandible resembling odontogenic cyst in a panoramic radiograph

Ameloblastic carcinoma is a rare odontogenic tumor exhibiting histologic evidence of malignancy in the primary or recurrent tumor, regardless of whether it has metastasized or not. Most ameloblastic carcinomas are presumed to have arisen de novo, with few cases of malignant transformation of ameloblastoma being apparent. A case is reported of a 21-year-old caucasian female with ameloblastic carcinoma in the left angulus area of the mandible resembling an odontogenic cyst in the panoramic radiograph. In addition to the panoramic radiograph, computerized tomography (CT) and magnetic resonance (MR) images were taken preoperatively. This report demonstrates that CT or MR examinations may be crucial in differentiating odontogenic tumors from cysts.     

Ameloblastoma: analysis of 207 cases in a Nigerian teaching hospital.

OBJECTIVE: The aim of the study was to review all the cases of ameloblastoma seen at the Oral and Maxillofacial Surgery Clinic of the Lagos University Teaching Hospital, Nigeria, between 1980 and 2003. METHODS AND MATERIALS: In this retrospective study, case files and biopsy reports of new cases of ameloblastoma covering a 24-year period were retrieved and analyzed for sex, age on presentation, histologic type, and site distribution. RESULTS: A total of 207 cases of ameloblastoma were seen in the given period. One hundred and ninety-eight (95.7%) were benign, and 9 (4.3%) were malignant. A male-to-female ratio of 1.1:1 was found. The average ages on presentation for ameloblastoma and ameloblastic carcinoma were 31.67 and 46.44 years, respectively. The lesion was found to be more common in the premolar-molar region of the mandible. The most common histologic type was follicular ameloblastoma (25.1%). Nine (4.3%) cases of ameloblastic carcinoma were also reported. CONCLUSIONS: Ameloblastoma with a predilection for the posterior mandibular region is relatively common in our environment. Sex and site distributions are similar to previous reports in the literature.     

The histologic similarity between craniopharyngioma and odontogenic lesions: a reappraisal

The histologic similarities between the craniopharyngioma and the ameloblastoma are well recognized and supported by their common embryologic origin from oral ectoderm. Differences in these lesions include a greater tendency for craniopharyngiomas to be cystic and form ghost cells and calcifications. The keratinizing and calcifying odontogenic cyst (KCOC), a lesion that features proliferating ameloblastic epithelium, ghost keratin, calcification, and cyst formation, may more precisely mimic the craniopharyngioma. The histologic features of twenty-seven craniopharyngiomas were studied. Twenty cases resembled KCOC microscopically. Two examples duplicated the histologic features of infiltrative ameloblastoma, while five showed characteristics of both lesions. This study shows that the range of histologic features in craniopharyngioma includes and spans both odontogenic lesions but more often simulates KCOC. The results suggest that the KCOC and the ameloblastoma may be closely related developmentally.     

Ameloblastic carcinoma of the jaws: A report of two cases

Two cases of ameloblastic carcinoma of the jaws are reported. Histopathologically, the lesions showed cytologic features of malignancy in addition to classical ameloblastoma patterns and were therefore documented as examples of ameloblastic carcinoma. The negative cytokeratin expression by the malignant cells on histochemical analysis is notably different from that normally observed in classical ameloblastomas.     

Ameloblastic fibroma: report of case.

A 3-year-old girl had a large, painless, radiolucent lesion that involved the right side of the mandible. The lesion extended from the canine region to the condyle and coronoid process. A microscopic diagnosis of ameloblastoma was made by the hospital pathologist. Because it is unusual to find an ameloblastoma in a 3-year-old child and because the extensive surgical procedure that would be necessary to remove an ameloblastoma of this size, further consultation was required. As a result, the lesion was diagnosed as an ameloblastic fibroma and a more conservative surgical procedure was performed. Sixteen months after surgery, radiographic evidence showed complete resolution of the bony surgical defect, with no evidence of recurrence. This case once again points out the necessity for exact diagnosis of similar histologic lesions that may require a different approach in treatment.     

Ameloblastic carcinoma ex ameloblastoma: report of a case-possible involvement of CpG island hypermethylation of the p16 gene in malignant transformation

Ameloblastic carcinoma is described in the updated World Health Organization (WHO) classification as a rare malignant lesion. Ameloblastic carcinoma meeting the WHO criteria may arise either as a result of malignant change in a pre-existing benign ameloblastoma (carcinoma ex ameloblastoma) or as a primary malignant ameloblastoma not preceded by an ordinary ameloblastoma (de novo carcinoma). We report a case of ameloblastic carcinoma ex ameloblastoma and examine how this case underwent malignant transformation. The DNA was extracted separately from benign and malignant areas in paraffin sections of the tumor. Direct sequencing showed no genetic mutation of exons 5-8 of the p53 gene. Hypermethylation of CpG islands of the p16 gene was detected in the malignant parts of the tumor. The results indicate that hypermethylation of p16 may have been involved in the malignant transformation of the ameloblastoma in the present case.     

Ameloblastic carcinoma. Report of an aggressive case and review of the literature

Odontogenic carcinomas of the jaws are classified as malignant ameloblastoma, ameloblastic carcinoma or primary intraosseous carcinoma. Because these lesions are extremely rare, microscopic diagnosis is difficult. An aggressive case of ameloblastic carcinoma of the mandible is presented. In spite of radical surgery and radiotherapy, the patient expired eight months following initial diagnosis. - A review of the literature seems to indicate that so called simple ameloblastomas rarely can dedifferentiate and metastasize following multiple inadequate surgical procedures. Although radical surgery is not necessary, local excision should be thorough. - Ameloblastic carcinoma and primary intraosseous carcinomas may be histogenetically similar. They are highly malignant tumours which should be treated aggressively. Metastasis is common and prognosis is poor.     

Calcifying odontogenic cyst with ameloblastic fibroma: report of three cases

Although it is a rare event, odontogenic tumors such as ameloblastoma, ameloblastic fibroma (AF), ameloblastic fibro-odontoma, and odontoma have been reported associated with calcifying odontogenic cyst (COC). There are only four cases of COC with AF cited in the English literature. However, three of these four cases were either included in a review of a series of cases or reported as an abstract, and limited clinical and histological information was provided. We present three additional cases of COC with AF and discuss the management for this combined lesion. Because COC is known for its histologic diversity and variable clinical behavior, and the clinical significance of an association of COC with AF is still unknown, we think it is valuable to report COC with AF with detailed clinical and pathological documentation.     

造釉细胞癌的临床病理学研究

对于造釉细胞癌的临床生物学行为尚缺乏足够的认识。本文对２７例造釉细胞癌及随机抽取的３０例造釉细胞瘤病例进行对比分析,结果表明：２７例造釉细胞癌中,１９例发生于下颌骨,８例发生于上颌骨,与对照组相比（１４：１）差异显著;对２６例造釉细胞癌病人随访６－３４访年,术后５年生存率为１００％。提示上颌骨造釉细胞癌发生的机率比造釉细胞瘤大;造釉细胞癌后预后一般较好,手术后应即时修复颌面部组织缺损。     

牙源性肿瘤的印片细胞学与组织学比较的探讨

本文对35例牙源性肿瘤的印片细胞学及组织学图像进行了比较性探讨。体会到印片细胞学不仅方便、快捷，可以鉴别组织类型。并且牙源性肿瘤为颌骨内肿瘤，不方便做术前活检；肿瘤内含有骨小梁及钙化物，又不能做冰冻切片。而在手术中取材用印片细胞学进行快速诊断，指导制订治疗计划，有其特殊的，不可替代的优点，值得向同道们介绍推广。     

Ameloblastic Carcinoma

Ameloblastic carcinoma (AC) is a rare aggressive malignant epithelial odontogenic tumor of the maxillofacial skeleton with a distinct predilection in the mandible. It may appear de novo or originate from a pre-existing ameloblastoma or odontogenic cyst. It exhibits cytological features of ameloblastoma and carcinoma. It may present as a cystic lesion with benign clinical features or as a large tissue mass with ulceration, significant bone resorption and tooth mobility. The clinical course of ameloblastic carcinoma is typically aggressive, with extensive local destruction. Direct extension of the tumour, lymph node involvement and metastasis to various sites has been reported. Wide local excision is the treatment of choice. Regional lymph node dissection should be considered and performed selectively. Radiotherapy and chemotherapy have limited role in the treatment of ameloblastic carcinomas. Close periodic reassessment of the patient is mandatory.