Cell proliferation proteins and aggressiveness of histological variants of ameloblastoma and keratocystic odontogenic tumor

The Effect of Conservative vs. Radical Treatment of Ameloblastoma on Recurrence Rate and Quality of Life: An Umbrella Review

Ameloblastoma is a rare, benign, but locally aggressive odontogenic tumor that originates from the epithelial cells involved in tooth development. The surgical approach to treating an ameloblastoma depends on the type, size, location, and extent of the tumor, as well as the patient's age and overall health. This umbrella review's aim is to summarize the findings from systematic reviews (SRs) and meta-analyses on the effect of radical or conservative treatment of ameloblastoma on the recurrence rate and quality of life, to evaluate the methodological quality of the included SRs and discuss the clinical management. Three electronic databases (PubMed, Scopus, The Cochrane Library) were checked. The primary outcome was the recurrence rate after surgical treatment, while the secondary outcomes were the post-operative complications, quality of life, esthetic, and functional impairment. The methodological quality of the included SRs was assessed using the updated version of "A Measurement Tool to Assess Systematic Review" (AMSTAR-2). Eighteen SRs were included. The quality of the included reviews ranged from critically low (three studies) to high (eight studies). Four studies were included in meta-analysis, and they revealed that the recurrence rate is about three-times more likely in the conservative treatment group compared to the radical treatment group, and this result is statistically significant. Despite the high recurrence rate, the latter was more appropriate in the case of smaller lesions and younger patients, due to better post-operative quality of life and reduced functional and esthetic impairments. Based on the results of this overview, conservative treatment may be recommended as the first-line approach for intraosseous ameloblastoma not involving soft tissue. However, given the expectation of a higher recurrence rate, it is advisable to reduce the interval between follow-up visits. However, further prospective studies are needed to establish the best treatment choice and follow-up period.

A Retrospective Analysis of 129 Ameloblastoma Cases: Clinical and Demographical Trends from a Single Institution

Ameloblastomas are benign neoplasms of the jaw, but frequently require extensive surgery. The aim of the study was to analyze the demographic and clinicopathological features of ameloblastoma cases at a single Oral and Maxillofacial Surgery group in the United States.

STUDY DESIGN

A retrospective chart review of patients evaluated for ameloblastoma between 2010 and 2020 at a single tertiary care center. Age, race, sex, tumor size, tumor location, and histological subtypes were recorded.

RESULTS

A total of 129 cases of ameloblastoma were recorded with a mean patient age of 42 ± 18.6 years (range 9-91 years old), male to female ratio 1.08:1. Ameloblastoma presenting in the mandible outnumbered maxilla in primary (118 to 8, respectively) and recurrent cases (8 to 1, respectively). There was a higher prevalence of ameloblastoma in Black patients (61.3%) with mean age of Black patients occurring at 40.5 years and the mean age of White patients occurring at 47.8 years and mean tumor size trended larger in the Black patients (15.7 cm2) compared to White patients (11.8 cm2).

CONCLUSION

Data suggests a strong influence of racial factors on the incidence of ameloblastoma, with regards to size, Black patients with ameloblastoma trended higher and more data is needed to clearly elucidate any relationship between the tumor size and race, as other factors may influence the size (such as time to discovery).

Immunohistochemical evaluation of yes-associated protein molecule in the odontogenic epithelium of different histopathological variants of ameloblastoma and unicystic ameloblastoma

Background

Ameloblastoma is one of the major odontogenic neoplasms with an invasive and recurrence potential. Its tumourigenesis and proliferative capacity can be attributed to the activation or inactivation of certain molecular signalling pathways. Hippo signalling pathway is known to regulate diverse physiological processes related to mitosis and organ growth and is an emerging tumour suppressor pathway, the dysfunction of which is implicated in various diseases including cancers. Yes-associated protein1 (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are the downstream effectors in the Hippo cascade, which on nuclear activation leads to cellular proliferation in various tumours.

Aim

The current study was undertaken to evaluate the expression of YAP in various histopathological variants of ameloblastoma and unicystic ameloblastoma.

Materials and Methods

Fifty formalin-fixed paraffin-embedded tissue samples of histopathologically diagnosed cases of ameloblastoma, and 10 histopathologically diagnosed cases of unicystic ameloblastoma were obtained from the departmental archives to evaluate the immunohistochemical expression of YAP both manually and by software analysis.

Results

More than 90% of cases of conventional ameloblastoma and unicystic ameloblastoma elicited positive expression of YAP. No statistical difference was found among different histopathological variants of conventional ameloblastoma. Significant difference between the means of all four quantitative score groups was observed.

Conclusion

In view of the modulating effect of YAP in tumourigenesis and its higher expression in ameloblastoma, further exploration of this molecule appears to be a promising area of research.

Immunohistochemical study of the plasminogen activator system in benign epithelial odontogenic lesions

The aim of this study was to analyze and compare the immunohistochemical expression of plasminogen activator system (PAS) proteins (uPA, uPAR, and PAI-1) in ameloblastomas (AMBs), odontogenic keratocysts (OKCs), and dental follicles (DFs) representing normal odontogenic tissue, as well as to investigate possible correlations between these proteins. Twenty AMBs, 20 OKCs, and 10 DFs were selected for immunohistochemical analysis. In each case, the immunoexpression of uPA, uPAR, and PAI-1 was evaluated semiquantitatively based on the percentage of positivity in odontogenic epithelial and connective tissue cells. The epithelial immunoexpression of uPA was significantly lower in AMBs when compared to OKCs (p = 0.001) and DFs (p = 0.029). Significantly higher epithelial immunostaining for uPAR was observed in AMBs when compared to OKCs (p < 0.001). There were no significant differences in the epithelial immunoexpression of PAI-1 between AMBs and OKCs (p = 1.000). The correlations found for the expression of the studied proteins were not statistically significant (p > 0.05). However, the epithelial and connective tissue expressions of uPAR have a strong positive and statistically significant correlation in AMBs. The present results suggest that uPA is involved in the pathogenesis of OKCs and that uPAR may participate in tumorigenesis in AMBs. The high percentage of PAI-1-positive cells suggests a possible role for this protein in the development of AMBs and OKCs. Furthermore, the studied proteins do not seem to act synergistically in AMBs, OKCs, and DFs.

Consistency of color-deconvolution for analysis of image intensity of alpha smooth muscle actin-positive myofibroblasts in solid multicystic ameloblastomas

Ameloblastoma is an odontogenic tumor with a slow, locally aggressive growth pattern and multiple clinico-histologic types. The number of stromal myofibroblasts within ameloblastoma often is correlated with growth and aggressiveness. Color-deconvolution to separate different colors of immunostained tissues is a promising approach to quantifying myofibroblasts in tumors such as ameloblastoma. We investigated the reliability of the color-deconvolution method using cross-sectional design to evaluate alpha-smooth muscle actin (α-SMA)-positive myofibroblasts in solid multicystic ameloblastoma. Formalin fixed tissues of eight cases of solid multicystic ameloblastoma were immunostained for α-SMA using the horseradish peroxidase-diaminobenzidine (HRP-DAB) method. Color-deconvolution using ImageJ software was used to quantify the staining intensity of brown DAB α-SMA stained myofibroblasts. Color-deconvoluted images of brown DAB stained tissues exhibited distinct morphological features of solid multicystic ameloblastoma with α-SMA stained myofibroblasts distributed abundantly adjacent to the ameloblastoma epithelial islands. The computed image intensity of α-SMA stained myofibroblasts was quantitatively similar among the different ameloblastoma samples. A combination of color-deconvolution and α-SMA staining of myofibroblasts is a useful diagnostic tool for evaluating histologic differentiation and growth pattern of ameloblastoma.