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Objective: The aim of this study was to report the clinicopathologic features of 105 new cases of adenomatoid odontogenic tumor (AOT) from Brazil, Guatemala, Mexico, and South Africa., Study Design: Clinical and radiographic data were collected from records of 5 oral pathology laboratories, and all cases were microscopically reviewed., Results: This series of cases included 36 (34.2%) from South Africa; 33 (31.4%) from Brazil; 23 (21.9%) from Mexico; and 13 (12.3%) from Guatemala. Seventy-two patients (68.5%) were females and 33 patients (31.4%) were males, with an average age of 19.2 years. The tumors predominantly affected the anterior maxilla (48.5%), followed by the anterior mandible (29.5%); posterior mandible (15.2%); and posterior maxilla (6.6%). Sixty-three tumors (63.6%) were follicular, 34 (34.3%) were extrafollicular, and 2 (2%) were peripheral. In most cases, the tumors caused considerable cortical expansion (average size 3.4 cm). Microscopically, most cases showed rosette-like and duct-like structures., Conclusions: This is one of the largest case series of AOTs reported in the literature and the first multicenter study involving populations from Latin America and South Africa. In a fifth of the present cases, the posterior regions of the gnathic bones were affected and the tumors demonstrated larger sizes compared with cases occurring in other populations., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Ameloblastoma is a locally aggressive neoplasm with a poorly understood pathogenesis. Therefore, the aim of this study is to investigate whether COX-2 expression is associated with ameloblastoma microvascular density (MVD) and with tumor aggressiveness. Sixty-three cases of primary ameloblastomas arranged in tissue microarray were submitted to immunohistochemistry against cyclooxigenase-2 (COX-2) and CD34. Clinicopathological parameters regarding sex, age, tumour size, tumour duration, tumour location, treatment, recurrences, radiographic features, vestibular/lingual and basal cortical disruption and follow-up data were obtained from patients' medical records and correlated with the proteins expression. The results on BRAF-V600E expression were obtained from our previous study and correlated with COX-2 and CD34 expressions. Log-rank univariate analysis and multivariate Cox regression model were done to investigate the prognostic potential of the molecular markers. Twenty-eight cases (44.4%) exhibited cytoplasmic positivity for COX-2, predominantly in the columnar peripheral cells, with a mean MVD of 2.2 vessels/mm 2 . COX-2 was significantly associated with recurrences (p < 0.001) and BRAF-V600E expression (p < 0.001), whereas lower MVD was associated with the use of conservative therapy (p = 0.004). Using univariate and multivariate analyses, COX-2 was significantly associated with a lower 5-year disease-free survival (DFS) rate (p < 0.001 and p = 0.012, respectively), but not with a higher MVD (p = 0.68). In conclusion, COX-2 expression in ameloblastomas is not associated with MVD, but it is significantly associated with recurrences and with a lower DFS., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Background: Fibroblast growth factor 2 (FGF2) and FGF receptor 1 (FGFR1) have been investigated in different human neoplasms and were shown to play important roles in the pathogenesis of these diseases; however, very few are known regarding their prognostic importance in the context of ameloblastoma. Therefore, the aim of this study was to investigate whether the expression of FGF2 and FGFR1 is associated with ameloblastoma clinical behavior., Methods: Fifty-eight cases of ameloblastoma arranged in tissue microarray were submitted to immunohistochemistry against FGF2 and FGFR1. Clinicopathological parameters regarding sex, age, tumor size, duration and location, treatment, recurrences, radiographic features, cortical disruptions, and follow-up data were obtained from patients' medical records and correlated with the molecules expression. Univariate and multivariate Cox regression analyses were used to investigate the prognostic potential of the biomarkers., Results: Forty-four cases (75.9%) exhibited cytoplasmic positivity for FGF2 in central and peripheral epithelial cells, 46 of 58 (79.3%) showed FGFR1 cytoplasmic positivity predominantly in the columnar peripheral cells, and 43 cases (74.1%) were positive for both. Expression of FGF2 and FGF2 + FGFR1 was associated with tumor recurrences (P = .05). However, univariate and multivariate analyses did not demonstrate a significant influence of FGF2, FGFR1, or FGF2 + FGFR1 in the 5-year disease-free survival (DFS) rate (P = .27, P = .33, and P = .25, respectively)., Conclusion: Cytoplasmic expression of FGF2 and FGF2 + FGFR1 is associated with ameloblastoma recurrence, but FGF2 and FGFR1 are not determinants of a lower DFS., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Ameloblastoma is a benign but locally aggressive odontogenic tumor, while ameloblastic carcinoma is its malignant counterpart. Angiogenesis and lymphangiogenesis in malignancies have been correlated with higher aggressiveness and poor prognosis, as well as greater expression of podoplanin by tumoral cells., Methods: Immunohistochemical expression of podoplanin, CD34, and CD105 (endoglin) was evaluated in 53 ameloblastomas and three ameloblastic carcinomas; additionally, immunohistochemistry for podoplanin was also performed in 10 tooth germs. Microvessel density of blood and lymphatic vessels was calculated and compared between ameloblastomas and ameloblastic carcinomas. Immunoexpression of podoplanin by ameloblastic cells was evaluated in tooth germs, ameloblastomas, and ameloblastic carcinomas., Results: Podoplanin was similarly expressed by odontogenic epithelial cells of tooth germs and ameloblastomas, while its expression was lower in ameloblastic carcinomas. There was no difference in microvessel density assessed by CD34 between ameloblastomas and ameloblastic carcinomas; nevertheless, the latter presented higher amounts of lymphatic and new formed blood vessels., Conclusions: Results suggest that podoplanin does not seem to be involved in invasion mechanisms of ameloblastic carcinomas, as its expression was decreased in the malignant tumoral cells. On the other hand, the increased lymphatic microvessel density and neoangiogenesis found in ameloblastic carcinomas could be related to its aggressiveness and potential for metastasis., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objective: The aim of this study was to investigate hMutS proteins in developing human tooth, ameloblastomas, and ameloblastic carcinoma and to determine whether the expression of these proteins has any prognostic potential., Study Design: Ten cases of developing human tooth, 39 ameloblastomas, and 2 ameloblastic carcinomas were used to determine the distribution of the proteins during the process of carcinogenesis. Simultaneously, another sample of 73 ameloblastomas was arranged in tissue microarray, and their clinical, microscopic, and radiographic features; treatment outcome; presence of BRAF-V600E mutation; and follow-up data were assessed to determine the prognostic relevance of the expression of hMutS (hMSH2, hMSH3, hMSH6) and Ki-67. hMSH2 and hMSH6 were significantly downexpressed in ameloblastomas (P = .0059) compared with developing human tooth (P < .0001)., Results: hMSH2, hMSH3 expression were significantly associated with BRAF-V600E mutation (P < .05). Simultaneous overexpression of hMutS was associated with recurrence (P = .035); however, these did not predict the disease-free survival of patients (P > .05)., Conclusions: hMutS proteins are downregulated in ameloblastoma; moreover, simultaneous overexpression of these proteins in ameloblastoma was associated with recurrence but did not predict disease-free survival., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: Ameloblastoma is a locally aggressive odontogenic tumor with high rates of recurrence. To better understand the molecular basis of ameloblastoma, tissue microarray (TMA) may represent a useful tool. However, despite TMA has been considered a high-throughput technique for different human neoplasms, it remains to be validated in the ameloblastoma context. Therefore, the objective of this study was to validate TMA for immunohistochemical study of ameloblastoma, determining its most appropriate design., Methods: Forty cases of ameloblastoma were manually distributed in two TMA blocks assembled in triplicate containing 1.0- and 2.0-mm cores (20 cases each). Immunohistochemistry for cytokeratins 14 and 19, and Bcl-2 and Ki-67 was performed, and semiquantitative analysis was performed. Results obtained with TMA sections were compared to their corresponding conventional whole-section slides (CWSS)., Results: Kappa statistical test demonstrated that both 1.0- and 2.0-mm cores assessed as duplicate or triplicate significantly correlated with CWSS, with higher levels obtained using Ki67 (k = 0.98, 0.97, 0.88, 0.87) and CK19 (k = 0.62, 0.58, 0.85, 0.85). There was no significant difference between 1.0- and 2.0-mm cores, and between duplicate and triplicate values. 1.0-mm TMA showed a higher index of core loss (33.74% vs. 4.99%)., Conclusion: Using a manual arrayer, it was demonstrated that 1.0-mm TMA arranged in duplicate is a valid method for ameloblastoma immunohistochemical study with satisfactory levels of agreement between TMA cylinders and CWSS., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Ameloblastic carcinoma is rare, accounting for 1.5%-2.0% of all odontogenic tumors. Few small series are available, but data on its clinicopathologic characteristics derive mainly from single case reports; therefore, descriptions of new cases may help to better understand the biological characteristics of this rare odontogenic malignancy. In the current report we describe an ameloblastic carcinoma affecting a 27-year-old female patient who had a previous diagnosis of ameloblastoma 7 years before. The carcinoma featured extensive areas of squamous differentiation resembling a primary intraosseous squamous cell carcinoma, as well as areas of dedifferentiation, a poorly documented histologic characteristic of ameloblastic carcinoma. This case provides new insights on the microscopic spectrum of ameloblastic carcinoma, permitting a critical discussion of the current World Health Organization classification of this odontogenic tumor., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Introduction: The purpose of this study was to describe a series of unicystic ameloblastomas (UAs) that presented clinical and radiographic similarities to apical periodontitis in order to call the attention of clinicians to the fact that several different diseases are able to mimic endodontic periapical lesions., Methods: A retrospective clinicopathological analysis of 5 patients who had periapical lesions in the mandible initially diagnosed as apical periodontitis but with a final histologic diagnosis of UAs is presented., Results: Three men and 2 women with a mean age of 26.4 years presented lesions involving the posterior mandible. No patient reported pain, and 3 patients showed pulp vitality of the involved teeth. Radiographically, all lesions presented periapical well-defined radiolucencies, ranging from 2 to 3 cm in diameter, and 3 cases presented root resorption. Endodontic therapy was applied in 2 patients who were referred to our clinics because of a lack of involution of the periapical lesions. All patients were submitted to periapical surgical curettage and histologically diagnosed as UA. After a mean follow-up of 45.6 months, all patients are well without signs of recurrence., Conclusions: UA may involve the periapical area of teeth, mimicking an inflammatory lesion of endodontic origin. The diagnosis of periapical lesions should be determined based on clinical and radiographic aspects. Recalcitrant lesions should be surgically explored and submitted to histologic evaluation. The early diagnosis of nonendodontic lesions mimicking apical periodontitis such as UA may prevent unnecessary endodontic treatment and wide surgical resections., (Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

In this study we present a rare case of peripheral desmoplastic ameloblastoma and discuss its clinical features, histopathology, and immunohistochemical profile. This article reports a new case of this unusual neoplasm in a 66 year-old woman in which the main complaint was an asymptomatic swelling located in the right body of mandible. Histopathological findings were similar to the two previously reported cases of this tumor. Positive immunohistochemical stain for laminin V and type IV collagen suggests an inductive effect of the epithelium over the stroma while the low index of p53 protein and Ki-67 expression in epithelium and stromal cells, as well as CD138 uniform positive-stain in epithelial cells, support the benign biological behavior of this lesion. Including this new case, currently there are only three reports of this rare neoplasm. Reports of new cases of peripheral desmoplastic ameloblastoma are necessary for a better understanding of the origin and behavior of this particular subtype of ameloblastoma.

The aims of the present study were to examine whether the pattern of syndecan-1 expression correlates with cellular proliferation index in desmoplastic ameloblastomas (DA), peripheral ameloblastomas (PA) and ameloblastic carcinomas (AC), and to compare with that previously reported for solid (SA) and unicystic (UA) variants of ameloblastoma. Immunohistochemistry was performed for syndecan-1 and Ki-67 in seven ameloblastomas (four DA and three PA) and three AC. Expression of syndecan-1 was related to the histological subtype of tumors and, in the case of malignancy, to lower expression levels observed in AC (22.5%) than in PA (47.5%) or DA (77.5%) (P < 0.05). Syndecan-1 expression correlated inversely with Ki-67 proliferative index: the expression was lower in both types of ameloblastomas (1.5% in DA and 6.4% in PA) than in AC (41.2%; P < 0.05). The present results suggest that the decrease in syndecan-1 expression and increase in the Ki-67 index observed in AC is in accordance with its higher aggressiveness as compared to the rare DA and PA. Interestingly, DA had a lower proliferation index as well as the highest levels of syndecan-1 expression. These data suggest that DA differ from the other types of intraosseous ameloblastomas but more studies are necessary to better understand the role of this protein as a marker in the biological behavior of the epithelial odontogenic neoplasms.

Langerhans cell histiocytosis (LCH) is an uncommon myeloid neoplasm characterized by clonal neoplastic proliferation of Langerhans-type dendritic cells associated with a reactive inflammatory infiltrate composed predominantly of lymphocytes and eosinophils. Only three cases of LCH mimicking periapical lesions have been reported in the English-language literature to date. Herein, we report a rare case of LCH involving the mandible of a 45-years-old woman mimicking microscopically and radiographically a residual cyst. The patient underwent enucleation and curettage of the lesion. Microscopically, the lesion showed fibrous tissue with an intense inflammatory infiltrate and histiocytes with irregular to elongated nuclei with prominent nuclear grooves. The tumor cells were positive for S-100 protein, CD1a, and CD207. After careful evaluation through imaging tests to rule out lesions in other anatomical locations, the diagnosis was solitary LCH of the mandible. After four years of follow-up, the patient remained with no evidence of recurrence. This case emphasizes the importance of a carefully clinical, radiographic, and microscopical evaluation of bone lesions, including periapical or residual cysts, since some neoplasms can mimic common benign lesions of the jaws. Although conservative approaches to treating solitary mandibular bone lesions of LCH can be employed, long-term follow-up is strongly recommended. [ABSTRACT FROM AUTHOR]