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.     

Ectodermal odontogenic tumours: analysis of 197 Nigerian cases

This article presents a clinico-pathologic analysis of 197 cases of ectodermal odontogenic tumours archived in the Lagos University Teaching Hospital, Lagos Nigeria over a 21-year period. They were categorized according to the WHO classification of odontogenic tumours. Of the 197 cases, 182 (92.3%) were benign while 15 (7.6%) were malignant. Central ameloblastoma, which accounted for 88.3% in this series, was the most common benign neoplasm demonstrating predilection for males (58.6%) and the mandible (83.3%). The mean age of occurrence (+/-SD) was 31.00 +/- 13.9 (range 9-82 years). Similarly ameloblastic carcinoma was the most prevalent malignant tumour (5.6%) with a predilection for females (63.6%) and the mandible (81.8%). The mean age of occurrence (+/-SD) was 30.1+/- 20.7 (range 16-85) years. Follicular ameloblastoma was found to be the commonest histologic subtype seen in Nigeria.     

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.     

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 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.     

Odontogenic tumors: a review of 319 cases in a Nigerian teaching hospital

OBJECTIVE: This study sought to determine the relative frequency of odontogenic tumors in a Nigerian population and to compare these data with previous reports. STUDY DESIGN: Records of patients seen at the Lagos University Teaching Hospital between January 1980 and December 2003, with histologic diagnosis of odontogenic tumors (based on World Health Organisation classification, 1992), were analyzed. RESULTS: Odontogenic tumors constituted 9.6% of all the biopsies of oral and jaw lesions seen within the period under study. Three hundred and eight (96.6%) were intraosseous, and 11 (3.4%) were peripheral (peripheral odontogenic fibroma=7; peripheral myxoma=3; peripheral ameloblastoma=1). The mean age of patients was 29.9+/-15.6 years (range, 4-85 years). Among these cases, 96.6% of the tumors were benign and 3.4% were malignant. Ameloblastoma with predilection for the mandible was the most frequent odontogenic tumor (63%), followed by adenomatoid odontogenic tumor (AOT) (7.5%), myxoma (6.5%), calcifying epithelial odontogenic cyst (5.3%), and odontogenic fibroma (5.3%). More cases of malignant odontogenic tumors were seen than cases of calcifying epithelial odontogenic tumor and odontomas. The mean ages of patients with AOT, ameloblastic fibroma, and odontoma were significantly lower than those with ameloblastoma ( P<.05). No significant difference was found between the mean ages of patients with benign odontogenic tumors and those with malignant odontogenic tumors ( P=.058). CONCLUSIONS: Odontogenic tumors, especially ameloblastoma, are not considered rare among Nigerians, whereas odontoma, regarded as the most frequent odontogenic tumor in North and South America, is rare.     

Ameloblastic carcinoma: case report and review

The histologic classification for odontogenic carcinomas is still under revision; thus, the differentiation between the terms "malignant ameloblastoma" and "ameloblastic carcinoma" has not been definitely stated. Nevertheless, it is recommended to reserve the former for those lesions that, in spite of an apparently innocuous histology, have given origin to metastatic growths, and to apply the latter for those ameloblastomas in which there is histologic evidence of malignancy in the primary, recurrent or metastatic lesions. A case of an ameloblastic carcinoma in the mandible is presented. Histologically, it was characterized by areas with features of a typical ameloblastoma and areas with anaplastic appearances.     

Ameloblastoma: a surgeon's dilemma.

PURPOSE: To investigate whether there were any significant differences in the mode of presentation, treatment, and outcome of patients presenting with a primary diagnosis of ameloblastoma in Glasgow, Scotland and San Francisco, CA. MATERIALS AND METHODS: All cases of ameloblastoma seen in both institutions between January 1, 1980 and December 31, 1999 were included in this study. Mode of presentation, radiographic appearance, histologic appearance, treatment, and follow-up were recorded. RESULTS: There were no significant differences in the clinical features on presentation (swelling, followed by pain, and altered sensation), the radiographic appearance (unilocular approximately 30% and multilocular 70%), or management with either local treatment (enucleation and/or curettage in just over 50% of cases) or radical treatment (a form of resection in under 50%) in the 50 cases included in this study. Primary care by conservative treatment led to a recurrence in approximately 80% of cases and this included cases of unicystic ameloblastoma. CONCLUSION: The mode of presentation, diagnosis, and management of the ameloblastoma was remarkably similar in Glasgow and San Francisco. The recurrence rate following local enucleation and curettage was unacceptably high, and this included the cases of unicystic ameloblastoma, which should be treated more aggressively than has been recommended in the past.     

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.     

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 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.     

A review of 318 odontogenic tumors in Kaduna, Nigeria.

PURPOSE: To analyze 318 odontogenic tumors seen at a tertiary oral care center in Kaduna, Nigeria for comparison with findings in previous Nigerian and world records. MATERIALS AND METHODS: A retrospective survey of odontogenic tumors based on the classification of Kramer et al was undertaken at the Maxillofacial Unit, Ahmadu Bello University Teaching Hospital, Kaduna, Nigeria, from all histopathologically proven cases of tumors and tumor-like lesions of the oral and perioral structures. Data were retrieved from case notes, radiographs, histopathology results, and follow-up records. Information collected were used to complete a questionnaire and subjected to analysis. RESULTS: There were 990 tumor and tumor-like lesions of the oral and perioral structures, of which 318 were odontogenic tumors (32%). Twelve histopathologic types of odontogenic tumors were found with more benign (n=314; 99%) than malignant (n=4; 1%). Ameloblastoma made up 233 (73%) of the tumors, followed by odontogenic myxoma (n=38; 12%), ameloblastic fibroma (n=9; 3%), and the adenomatoid odontogenic tumor (2%). Three cases of calcifying odontogenic cyst were co-existent with ameloblastoma (2) and ameloblastic fibro-odontoma (1). Among 275 surgically treated odontogenic tumors, enucleation was performed in 64 cases (23%), dentoalveolar segment resection with preservation of lower border of the mandible (n=33; 12%), segmental resection (n=168; 61%), and composite resection (n=9; 3%); 1 case was deemed inoperable. At least 8 cases of ameloblastoma (13%) recurred out of 60 followed up. CONCLUSION: Ameloblastoma is a fairly common tumor of Nigerian Africans accounting for 73% of odontogenic tumors and 24% of all tumors and tumor-like lesions of the oral and perioral structures. Various forms of resection are practiced to eradicate the tumor in view of the late presentation in our environment. Patients in Nigeria do not often return for follow-up reviews. A minimum of 5 years of follow-up reviews are necessary after treatment of ameloblastoma.     

Expression of tenascin and nucleolar organizer region in ameloblastoma and ameloblastic fibroma

J Oral Pathol Med (2010) 39 : 223–229 Background: The aim of this study was to assess the expression, distribution and comparison of tenascin, a glycoprotein of the extracellular matrix in ameloblastoma and ameloblastic fibroma, both odontogenic neoplasms with diverse biological behavior and to understand the proliferative activity by using the morphometric analysis. Methods: Paraffin embedded tissue from 25 cases of odontogenic tumors i.e., ameloblastoma (n = 15) and ameloblastic fibroma (n = 10) were used. The expression of tenascin was evaluated using immunohistochemistry. Morphometric analysis of nucleolar organizer regions (NORs) from ameloblastoma and ameloblastic fibroma was carried out by silver staining. Results: A heterogeneous expression of tenascin was found in ameloblastoma which was mainly localized at the epithelial–mesenchymal interface and a patchy distribution was observed in the stroma (80%), while strong positivity was observed in the stroma and at the basement membrane zone of ameloblastic fibroma (100%). argyrophilic nucleolar organizer regions (AgNORs) revealed higher mean counts in ameloblastoma (3.093 ± 0.902) when compared with those of ameloblastic fibroma (1.553 ± 0.250). Ameloblastoma presented more than two NORs (two to five) per nucleus in majority of the cells, while ameloblastic fibroma exhibited only one NORs per nucleus. Conclusions: Expression of tenascin in these neoplasms suggest that it could play a role in epithelial‐ mesenchymal interaction, while AgNORs reveal that ameloblastomas are more aggressive when compared with ameloblastic fibromas.     

Relative frequency of peripheral odontogenic tumors: a study of 45 new cases and comparison with studies from the literature

BACKGROUND: Peripheral (extraosseous) odontogenic tumors are rare, and reports in the literature have mainly been single case reports or a small series of cases. The aim of this study was to determine the relative frequency of peripheral (extraosseous) odontogenic tumors relative to one another and relative to their central (intraosseous) counterparts in an oral pathology biopsy service and to compare these data with information available in the literature. METHODS: The files of the Pacific Oral and Maxillofacial Pathology Laboratory of the University of the Pacific, San Francisco, CA, USA, served as the source of material for this study. Files were systematically searched for all cases of peripheral odontogenic tumors (POTs) during a 20-year-period. RESULTS: There were 91,178 cases accessed in which central and POTs were identified in 1,133 (1.24%), central tumors in 1,088 (1.2%), and peripheral tumors in 45 (0.05%). Peripheral tumors accounted for 4% of all 1133 central and POTs. Peripheral odontogenic fibroma (PODF) was the most common of the 45 POTs accounting for 51.1% (23 cases) followed by peripheral ameloblastoma (PA) 28.9% (13 cases) and peripheral calcifying cystic odontogenic tumor (PCCOT) 13.3% (six cases). Peripheral calcifying epithelial odontogenic tumor, peripheral ameloblastic fibroma, and peripheral ameloblastic carcinoma were also identified--each comprised 2.2% (one case each). PODF was more common than its central counterpart by a 1.4:1 ratio. This was the only peripheral tumor that was more common than its central counterpart. PA accounted for 9.3% of all ameloblastomas and PCCOT for 26% of all calcifying cystic odontogenic tumors. CONCLUSION: There is only scarce information in the literature on the relative frequency of POTs. Additional studies should be conducted to determine the true relative frequency. To ensure accuracy, pathologists with experience in the field of odontogenic tumors should conduct these studies. Intraosseous tumors that perforate through the bone to the gingival tissue, clinically presenting as 'peripheral tumors' should be excluded.     

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.     

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。     

Ameloblastic fibroma: growth potentiality of odontogenic epithelium and coexpression of intermediate filament proteins in fibromatous cells

Four cases of ameloblastic fibroma are described immunohistochemically in terms of intermediate-sized proteins in both epithelial and mesodermal components. Keratin proteins were demonstrated by polyclonal anti-keratin antiserum (TK: detecting 41–65 kDa keratins) and 2 monoclonal antibodies to keratin (KL1: 55–57 kDa, PKK1: 44, 46, 52 and 54 kDa), and monoclonal antibodies to vimentin and desmin. Two types of odontogenic epithelial tumour cells were discriminated: undifferentiated odontogenic cells and common ameloblastoma cells. Keratin expression was found to be stronger in undifferentiated cells than in the ameloblastoma cells. Undifferentiated cells were PAS–positive, while ameloblastoma cells were negative. Fibroma cells were strongly positive for vimentin, and negative for desmin. Keratin proteins were also expressed slightly. Thus, coexpression of keratin and vimentin was seen in fibroma cells. Histogenesis is discussed from the standpoint of the distribution patterns of keratin and vimentin, as well as with respect to the histopathology.     

Ameloblastic carcinoma of the jaws. A report of three Nigerian cases.

Ameloblastic carcinoma is an exceptionally rare and aggressive orofacial neoplasm that belongs to a family of malignant epithelial odontogenic tumours. The aetiology remains largely unknown, however most cases are presumed to have arisen de novo, with few of them presenting following malignant transformation of ameloblastoma. We report our experience with three rare cases of ameloblastic carcinoma seen in Nigerians. This is an addition to the sparse literature and to our knowledge; there has been no such report from sub-Saharan Africa.