Glandular odontogenic cysts: A collaborative investigation of 22 cases and proteins related to invasiveness.

BACKGROUND: A glandular odontogenic cyst (GOC) has an intriguing, aggressive behaviour whose mechanisms have not yet been clarified. OBJECTIVE: To conduct a collaborative cross-sectional study on the clinical, demographic, microscopic and immunohistochemical characteristics of GOCs, emphasizing the histopathological characteristics and expression of proteins related to invasiveness. METHODS: Twenty-two cases of GOC from three oral and maxillofacial pathology services in Brazil were selected from 1988 to 2018. Clinical and demographic data were collected. Histopathological features were evaluated in detail. Sixteen cases of GOC were also submitted to immunohistochemistry to detect MT1-MMP, TKS4, TKS5 and cortactin, the key regulators of invadopodia formation. RESULTS: Glandular odontogenic cysts were primarily seen in men over 40 years of age, in the posterior mandible and the anterior maxilla as a unilocular, radiolucent lesion. All cases presented hobnail cells, clear cells and variable thickness of the lining epithelium, 3 of the 10 key histopathological parameters to be evaluated in GOCs. Immunohistochemistry revealed a greater expression of the studied proteins in the GOCs than in the controls (p < 0.0001). CONCLUSION: Overexpression of proteins that regulate cell invasiveness was identified, and the present study's findings suggest that invadopodia activity is a possible mechanism used by GOCs to promote local invasion, which could partly explain its intriguing biological behaviour.

Angiogenesis pattern and H3.3 histone mutation in aggressive and non-aggressive central giant cell lesions.

OBJECTIVE: The aim of this study was to evaluate angiogenesis in central giant cell lesions (CGCL) and its association with biological behavior. In addition, investigation of the histone H3.3 mutation was performed. DESIGN: Thirty-eight cases of CGCL were classified as aggressive (n = 9) or nonaggressive (n = 29). Cases were submitted to immunohistochemistry to compare angiogenesis using Wilms' tumor protein 1 (WT1), platelet endothelial cell adhesion molecule (CD31) and endoglin (CD105) between groups. To verify the presence of genic mutation, histone H3.3 was investigated. RESULTS: WT1 was expressed in mononuclear and giant cells of all cases. CD31 and CD105 were expressed in CGCL microvessels, with a higher CD105 microvascular density than CD31. No statistically significant difference was observed between groups. None of the cases studied showed the histone mutation. CONCLUSIONS: There was no difference between aggressive and nonaggressive lesions regarding the angiogenic markers. The expression of WT1 and CD105 suggests that CGCL presents a tumoral vascular pattern with high neoangiogenic activity. The absence of histone mutation may indicate that CGCL is not a true giant cell tumor.

A Rare Case of an Aggressive Clear Cell Variant of Calcifying Epithelial Odontogenic Tumor in the Posterior Maxilla.

A clear cell variant of calcifying epithelial odontogenic tumor is a rare benign odontogenic neoplasm, accounting for 33 cases described in the literature. In this article, we report a challenging example of clear cell variant of calcifying epithelial odontogenic tumor of the posterior maxilla in a 45-year-old female patient showing locally aggressive growth and recurrence. Microscopically, islands of polyhedral cells containing abundant cytoplasm, well-developed intercellular bridges blended with clear cells were observed. The nuclei were frequently pleomorphic and permeated by hyaline calcified material. Immunohistochemistry revealed positivity for pan-cytokeratin (AE1/AE3), cytokeratins (CK-14 and CK-19), Bcl-2, p53, and p63. The Ki-67 proliferative index was ~10%. As odontogenic tumors are rare, when a significant clear cell component is observed, the differential diagnosis with other lesions of the jaws with similar morphology, including other odontogenic tumors with prominent clear cell component, clear cell odontogenic carcinomas, and metastatic tumors, is difficult.

A Brazilian multicentre study of 2,497 isolated cases of odontogenic keratocysts.

We present the frequency of cases of isolated odontogenic keratocysts submitted to microscopic examination at 10 Brazilian referral centres in Oral and Maxillofacial Pathology. In a retrospective (1953-2017) analysis, data on clinicoradiographic features and treatment of these lesions were collected and analysed descriptively. Among the 258,867 cases retrieved, 2,497 (0.96%) were isolated odontogenic keratocysts. In summary, an overview of individuals affected with isolated odontogenic keratocysts is reported herein. This lesion showed predilection for the posterior mandible of young adult men.

Immune microenvironment and evasion mechanisms in adenoid cystic carcinomas of salivary glands.

OBJECTIVES: The objective of the present study was to investigate the expression of immune checkpoints (PD-L1, PD-L2, PD-1 and CTLA-4), immune inhibitory molecule HLA-G, markers of tumor-infiltrating lymphocytes (TIL) and dendritic cells (DC), as well as its association with clinicopathological features of adenoid cystic carcinomas (ACC) of the salivary glands. MATERIALS AND METHODS: Thirty-six samples from patients with ACC were analyzed immunohistochemically for the expression of PD-L1, PD-L2, PD-1, CTLA-4, HLA-G, CD8, GrB, CD1a and CD83. Positivity of HLA-G, PD-L1 and PD-L2 expression was defined by cut-offs values. CD8+ TIL was measured semiquantitatively and also using cut-off values obtained by the ROC curve considering recurrence of the lesion. RESULTS: ACC showed low CD8+, GrB+  TIL, CD1a and CD83 populations, as well as scarce positivity for CTLA-4 and PD-1. In contrast, PD-L2 and HLA-G expression was increased, while no PD-L1 expression was detected. Interestingly, cases with lower CD8+ TIL density presented greater recurrence rates. CONCLUSION: Our findings suggest that the ACC microenvironment exhibits low immunogenicity, represented by low TIL and DC density. Moreover, there seems to be activation of the immune inhibitory proteins/PD-L2 and HLA-G, a scenario that may favor tumor escape from the immune system and partially explain the poor prognosis of ACC.

Immune response and evasion mechanisms in lip carcinogenesis: An immunohistochemical study.

OBJECTIVES: Programmed death ligand-1 (PD-L1) and human leukocyte antigen-G (HLA-G) are considered immune checkpoint molecules that inhibit T-cell effectiveness, contributing to tumor immune escape. This study investigated PD-L1, HLA-G, CD8, and granzyme B (GrB) expression at different stages of lip carcinogenesis. DESIGN AND RESULTS: Forty cases of lip squamous cell carcinoma (LSCC), 55 actinic cheilitis (AC), and 10 healthy lip mucosa (HLM) were submitted to immunohistochemistry. Semiquantitative (PD-L1, HLA-G), and quantitative (CD8, GrB) analysis were performed. PD-L1 and HLA-G expression in neoplastic cells/keratinocytes and stroma/connective tissue was significantly higher in LSCC and AC, compared to HLM (p<0.05). PD-L1 was not associated with clinicopathological features of the lesions. HLA-G expression by malignant cells was significantly higher in LSCCs with distant metastasis (p = 0.041).CD8+ and GrB+ cell numbers progressively increased from HLMs to LSCC, with AC exhibiting intermediate numbers (p<0.01). Most LSCCs showed coexistence of PD-L1+ and CD8+ cells (72.5%). PD-L1 was directly correlated to CD8+ and GrB+ lymphocytic infiltration in LSCCs (p<0.05). Low cytotoxic immune response was associated with lymph node metastasis in LSCC (p<0.05). CONCLUSIONS: PD-L1 and HLA-G-mediated immune evasion mechanisms are likely to occur from early pre-malignant to advanced malignant stages of lip carcinogenesis, which might provide a rationale for therapeutic blockade of these pathways. PD-L1 expression in LSCCs was correlated with the cytotoxic markers, suggesting that PD-L1 may appear as an escape mechanism in response to an active antitumor response.

A multicentre study of oral paracoccidioidomycosis: Analysis of 320 cases and literature review.

OBJECTIVES: To investigate the frequency of oral paracoccidioidomycosis from representative geographical regions of Brazil and to compare the data with a literature review. MATERIALS AND METHODS: A retrospective study was conducted on 108,304 biopsies obtained from 1953 to 2016 at six Brazilian oral and maxillofacial pathology services. Demographic data and clinical and histopathological diagnosis of oral paracoccidioidomycosis were evaluated. A literature review of oral paracoccidioidomycosis studies published in three electronic databases was carried out. Data were analysed descriptively. RESULTS: A total of 320 cases of oral paracoccidioidomycosis were surveyed (0.3% of the oral lesions at the centres studied). The lesions were more frequent among male patients. The gingiva/alveolar ridge was the most affected site. Mean age of affected individuals was 51.3 years (±11.7). The literature review showed a higher incidence of oral paracoccidioidomycosis in the south-east and south regions of Brazil. Male individuals and individuals between 50 and 59 years were most affected. CONCLUSIONS: Oral paracoccidioidomycosis is an uncommon lesion observed in oral biopsy samples. The differences in the relative frequency of oral paracoccidioidomycosis are related to geographical variations. Men between 50 and 59 years are more affected. This study provides helpful information for clinicians in the diagnosis of oral paracoccidioidomycosis.

Overexpression of immunomodulatory mediators in oral precancerous lesions.

Human leukocyte antigen (HLA) G and E, programmed cell death 1 ligand 1 (PD-L1), IL-10 and TGF-ß are proteins involved in failure of the antitumor immune response. We investigated the expression of these immunomodulatory mediators in oral precancerous lesions (oral leukoplakia-OL; n=80) and whether these molecules were related to the risk of malignant transformation. Samples of normal mucosa (n=20) and oral squamous cells carcinoma (OSCC, n=20) were included as controls. Tissue and saliva samples were analyzed by immunohistochemistry and ELISA respectively. Fifteen OL samples showed severe dysplasia (18.7%) and 40 samples (50%) presented combined high Ki-67/p53. Irrespective of the degree of epithelial dysplasia and the proliferation/apoptosis index of OL, the expression of HLA-G, -E, PD-L1, IL-10, TGF-ß2 and -ß3 was higher to control (P<0.05) and similar to OSCC (P>0.05). The number of granzyme B+ cells in OL was similar to control (P=0.28) and lower compared to OSCC (P<0.01). Salivary concentrations of sHLA-G, IL-10 and TGF-ß did not allow for a distinction between OL and healthy individuals. Overexpression of immunosuppressive mediators in the OL reflects the immune evasion potential of this lesion, which is apparently independent of at cytological and proliferation/apoptosis status.

Immunohistochemical investigations on the expression of programmed cell death ligand 1, human leukocyte antigens G and E, and granzyme B in intraoral mucoepidermoid carcinoma.

OBJECTIVE: To identify the expression of nonclassical human leukocyte antigen G and E (HLA-G and -E), programmed cell death ligand-1 (PD-L1) and granzyme B (GB) in intraoral mucoepidermoid carcinomas (MECs), and to assess whether such expressions are related to metastasis, survival, staging, tumor grade and number of GB-positive cells. DESIGN: For this cross-sectional study, samples of MEC (n=30) were selected and classified as low-grade (LG), intermediate-grade (IG) or high-grade (HG), according to the WHO grading system. HLA-G, -E and PD-L1 were identified by immunohistochemistry and quantified as the proportion of positive neoplastic cells. The density of GB+ cells was also evaluated. The Kruskal-Wallis test was used with a 5% significance level. RESULTS: Expressions of HLA-G, -E and PD-L1 were identified in the majority of epidermoid, intermediate and clear cells, but not in the mucous cells of the MECs. The quantitative analysis of the total percentage of positive neoplastic cells showed overexpression of this set of proteins in all MEC samples. The expression of these proteins and histological grading were positively correlated [HLA-G (LG=79% positive cells, IG=96%, HG=99%; p=0.0004), HLA-E (LG=70%, IG=96%, HG=99%; p<0.0001) and PD-L1 (LG=34%, IG=79%, HG=80%; p=0.01)]. No relationship was observed between the immunosuppressive proteins and other clinicopathological parameters. Low GB density was found in all MEC samples. CONCLUSIONS: The augmented expression of HLA-G, -E and PD-L1 in the intraoral MEC might suggest a role of these molecules in the scape of neoplastic cells from immunosurveillance.