Immunohistochemical expression of podoplanin (D2-40), lymphangiogenesis, and neoangiogenesis in tooth germ, ameloblastomas, and ameloblastic carcinomas

Review on the Lymphatic Vessels in the Dental Pulp

Simple Summary

It is debatable whether lymphatic vessels exist in the dental pulp. Most researchers confirm their presence; however, the lymphatic system in the dental pulp is much less developed compared to other tissues of the body. Lymphangiogenesis occurs in the dental pulp with inflammatory changes as a response to inflammatory stimuli acting on the tooth. If lymphangiogenesis is defined as the development of lymphatic vessels from already existing ones, such a mechanism is possible only when lymphatic vessels are present in healthy teeth. Research papers have not conclusively proved whether lymphatic vessels can form in the dental pulp. The use of an immunohistochemical examination can very likely prove the presence of a lymphatic system in dental tissues. However, the evaluation of the lymphatic system of the teeth is problematic because it is quite difficult to clearly distinguish lymphatic vessels from small blood vessels.

Abstract

Despite many studies, opinions on the lymphatic system of the teeth are still incompatible. Studies using light and electron microscopy and directly using methods such as a radioisotope (radionuclide) scan and interstitial fluid pressure measurement reported incomplete results. Immunohistochemistry (IHC) plays the main role in investigating presence of the lymphatic system in dental tissues. This method uses labeled antibodies against antigens typical of lymphatic vessels. The use of appropriate staining enables the detection of antigen-antibody reaction products using a light (optical), electron or fluorescence microscope. However, these studies do not show the system of vessels, their histologic structure under physiological conditions and inflammation as well as the lymphangiogenesis process in the dental pulp. Unfortunately, there is a lack of studies associating the presence of lymphatic vessels in the dental pulp with local lymphatic nodes or large vessels outside the tooth. In the scientific and research environment, the evaluation of the lymphatic system of the teeth is problematic because it is quite difficult to clearly distinguish lymphatic vessels from small blood vessels. Despite many indications of the presence of lymphatic vessels in the pulp chamber, this problem remains open and needs further research.

BDNF/TrkB/Akt Signaling Pathway Epithelial Odontogenic Tumors and Keratocyst: An Immunohistochemical Study Comparative With Dental Germs

Odontogenic lesions (OL) are an important group of oral and maxillofacial diseases represented by odontogenic cysts, benign, and malignant tumors. The brain-derived neurotrophic factor (BDNF)/ tropomyosin receptor kinase B (TrkB) signaling pathway has multiple biological actions and has been identified as an important pathway in the proliferation, invasion, and survival of different epithelial tumors. Its role in the development of OL, however, has so far been unexplored. Our aim was to evaluate the BDNF/TrkB/Akt/p-RPS6 signaling pathway in OL of epithelial origin. This cross-sectional study comprised 3 cases of tooth germs, 25 cases of odontogenic keratocyst (OK), 29 cases of ameloblastoma (Am), and 6 cases of ameloblastic carcinoma. Immunohistochemical staining for BDNF, TrkB, p-Akt, and p-RPS6 was performed. OLs were evaluated according to the pattern of immunohistochemical expression in epithelial cells and by semiquantitative scores that considered the intensity of staining and percentage of positive cells. BDNF stromal expression was also assessed. No significant differences were observed with respect to the percentage of positive cases for all markers. Regarding the immunoreactive scores, BDNF and p-RPS6 expressions were similar in the odontogenic epithelium of all OL. However, TrkB and p-Akt were overexpressed in OK compared with ameloblastic carcinoma. In Am, epithelial BDNF was significantly higher compared with stromal expression. In conclusion, BDNF seems to participate in the development of cystic, benign, and malignant odontogenic epithelium to similar degrees. The acquisition of the invasive or malignant phenotype in odontogenic neoplasms is not associated with alterations in the BDNF/TrkB/Akt/RPS6 axis, which could be implicated in the differentiation process.

Report of a Rare Case of Spindle Cell Ameloblastic Carcinoma and the Diagnostic Utility of Immunohistochemistry

Ameloblastic carcinoma is a rare aggressive malignant epithelial odontogenic tumor. The spindle cell variant of ameloblastic carcinoma (SCAC) is exceedingly rare with 15 cases of SCAC having been reported. Therefore, because of the paucity of cases in literature related to SCAC, the biological behavior of the entity has not been well evaluated. Herein the authors report a case of incidentally diagnosed SCAC in a 20-year-old woman identified on imaging as part of the evaluation of a work-related facial injury. Histologically, the tumor had background of cystic ameloblastoma with areas of dense hypercellular spindle cells with short-to-long intersecting fascicles and occasional herringbone pattern intermixed with solid epithelial nests. Both the epithelial and spindle cells were positive for cytokeratin including cytokeratin 19, D2-40, and transducin-like enhancer of split proteins-1 immunohistochemical stains. The patient was followed for 18 months with no evidence of recurrence or metastasis. To the knowledge this is a first case of reporting D2-40 positivity in spindle ameloblastic carcinoma and this immunostain could be used as helpful marker to diagnose this entity.

Development of a biomarker of efficacy in second-line treatment for lymphangioma of the tongue: a pilot study

Lymphangioma of the tongue is a rare lymphatic malformation, and various authors have reported the successful use of sirolimus for its treatment. However, the safety of sirolimus in children needs further evaluation so that those who do not respond are not necessarily exposed to its potential adverse effects. We hypothesised that assessment of lymphangiogenesis can be used to predict whether the patient will respond to sirolimus, so we organised a prospective study after ethics committee approval had been given. After clinical and histological diagnoses of lymphangioma of the tongue had been confirmed, 16 patients were given sirolimus 0.8mg/day in three divided doses. Clinical response was assessed and compared with lymphatic microvessel density (LMVD), which was calculated immunohistochemically using the monoclonal antibody D2-40 as the lymphatic endothelial marker. Nine patients responded well, five partially, and two failed to respond. Mean (SD) LVD among the good responders was 21.00 (3.74), whereas among non-responders it was 8.00 (4.24). There was a significant difference in mean LVD between good responders, partial responders, and non-responders (p=0.04). Sirolimus is effective in treating children with lymphangioma of the tongue, and lymphangiogenesis is a useful therapeutic predictive marker.

Expression of CD34, VEGFR3 and eosinophil density in selected odontogenic tumors- a pilot study

Background

Limited statistically and clinically significant studies have been down on connective tissue factors in the odontogenic tumors. Therefore, the aim of this study was to determine the biological behavior of two selected epithelial odontogenic tumors (Ameloblastoma and Adenomatoid odontogenic tumor) by detecting CD34, VEGFR3 and eosinophil densities.

Methods

In this cross-sectional study, paraffin blocks including 20 cases of ameloblastoma and 20 (AOT), were selected. Totally, 4 sections were prepared for hematoxylin-eosin, Congo red staining, immunohistochemistry with CD34 and VEGFR3. Expression of VEGFR3, CD34 and lymphatic, blood vessels and eosinophil densities was examined.

Results

The mean of blood, lymphatic vessels and eosinophils densities in ameloblastoma were 14.9 ± 6.4, 4.4 ± 2 and 3.2 ± 2.7, respectively; and in AOT, they were 8.9 ± 3.4, 3.6 ± 1.3 and 1.2 ± 07, respectively. There was a significant difference in eosinophils and blood vessels densities between the two lesions (p = 0.005; p = 0.003). By increasing the density of eosinophils, the density of the blood vessels increased in both lesions (r = 0.539, P = 0.001) There was no positive relationship between eosinophils and lymphatic vessels densities in the two above mentioned odontogenic lesions (p = 0.288, R = 0.191).

Conclusion

It can be suggested that tumor angiogenesis and eosinophil densities may play a more effective role than lymphangiogenesis in local invasive behavior of ameloblastoma rather than AOT.

Comparison of fatty acid synthase and cyclooxygenase-2 immunoexpression in embryonal, benign, and malignant odontogenic tissues

OBJECTIVES

The aim of this study was to analyze the immunohistochemical expression of fatty acid synthase (FASN) and cyclooxygenase-2 (COX-2) in tooth germ (TG), ameloblastoma (AM), ameloblastic carcinoma (AC), ameloblastic fibroma (AF), and ameloblastic fibrosarcoma (AFS).

STUDY DESIGN

Immunohistochemistry for FASN and COX-2 was performed in 10 TG, 44 AM, 10 AC, 9 AF, and 5 AFS specimens. The results were analyzed by using the immunoreactive score (IRS) and Kruskal-Wallis test followed by Dunn's post-test.

RESULTS

Most TG specimens were strongly positive for FASN, whereas COX-2 was weak or negative. All AM and AC specimens expressed both proteins. In AF specimens, FASN and COX-2 were variably expressed in the epithelium and negative in the mesenchyme. In AFS specimens, FASN was strongly positive in the malignant mesenchyme and variable in the epithelium; COX-2 was focal or weak in both components. FASN expression showed significant differences in the following comparisons: TG vs AC, AM vs AC, and AF vs AFS. Differences in COX-2 were significant when comparing TG specimens with AM, AC, and AF specimens.

CONCLUSIONS

The results suggest that FASN and COX-2 overexpression may have a role in the pathogenesis of AM and AC, whereas in AFS, FASN seems to be mainly involved. Further studies are necessary to clarify these mechanisms and their clinical implications.

Lymph microvascularization as a prognostic indicator in neuroblastoma

Neuroblastoma is the most common extra-cranial solid pediatric cancer and causes approximately 15% of all childhood deaths from cancer. Although lymphatic vasculature is a prerequisite for the maintenance of tissue fluid balance and immunity in the body, little is known about the relationship between lymphatic vascularization and prognosis in neuroblastoma. We used our previously-published custom-designed tool to close open-outline vessels and measure the density, size and shape of all lymphatic vessels and microvascular segments in 332 primary neuroblastoma contained in tissue microarrays. The results were correlated with clinical and biological features of known prognostic value and with risk of progression to establish histological lymphatic vascular patterns associated with unfavorable histology. A high proportion of irregular intermediate lymphatic capillaries and irregular small collector vessels were present in tumors from patients with metastatic stage, undifferentiating neuroblasts and/or classified in the high risk. In addition, a higher lymphatic microvascularization density was found to be predictive of overall survival. Our findings show the crucial role of lymphatic vascularization in metastatic development and maintenance of tumor tissue homeostasis. These patterns may therefore help to indicate more accurate pre-treatment risk stratification and could provide candidate targets for novel therapies.

Is podoplanin expression associated with transforming growth factor-β signaling in odontogenic cysts and tumors?

BACKGROUND

Induction of podoplanin by transforming growth factor-β (TGF-β) has been shown in a number of lesions but not in odontogenic tumors (OTs). We evaluated the association between these markers in OTs for the first time and compared their expression among the different neoplasms.

METHODS

Immunohistochemistry using monoclonal antibody against podoplanin and TGF-β was performed on 76 odontogenic cysts and tumors. Spearman's correlation coefficient, Kruskal-Wallis, and Mann-Whitney U tests followed by adjustment with Bonferroni were used for statistical analysis (P < .05).

RESULTS

A significant difference in podoplanin expression was found among the lesions consisting of solid ameloblastomas, adenomatoid odontogenic tumors, ameloblastic fibromas, odontogenic myxomas (OMs), odontogenic keratocysts, and calcifying odontogenic cysts. Significant differences were observed only between OMs and each of the other neoplasms. Podoplanin immunostaining in the connective tissue was absent in most lesions. TGF-β was significantly different among the study sample but not between the lesions in paired comparisons. None of the studied OTs showed significant correlations between podoplanin-TGF-β, in either the epithelium or the stroma. These markers were also descriptively reported in calcifying epithelial odontogenic tumors.

CONCLUSIONS

The inductive effect of TGF-β on podoplanin seems to be limited, if any, in odontogenic lesions. Podoplanin appears to play a role in some aspects of OTs with epithelial or mixed origins. Despite the possible participation of podoplanin in tumorigenesis, it may not necessarily be involved in the aggressive behavior of OTs.

COX-2 as a determinant of lower disease-free survival for patients affected by ameloblastoma

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/mm². 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.