This study aimed to evaluate the density of the dendritic cells (DCs) and macrophages in oral leukoplakia (OL) and proliferative verrucous leukoplakia (PVL) by immunohistochemical analysis. We analysed paraffined tissue samples of PVL (n = 27), OL (n = 20), and inflammatory fibrous hyperplasia (n = 20) as the control group using the immunomarkers for DCs (CD1a, CD207, CD83, CD208 and CD123) and macrophages (CD68, CD163, FXIIIa and CD209). A quantitative analysis of positive cells in the epithelial and subepithelial areas was determined. Our results showed a reduction in CD208+ cells in the subepithelial area of the OL and PVL compared to the control. Additionally, we found a higher density of FXIIIa+ and CD163+ cells in the subepithelial area in PVL compared to the OL and control. Four-way MANOVA revealed a relationship between increased CD123+ cell density in the subepithelial area of “high-risk” samples regardless of disease. Macrophages provide the first line of defence against PVL antigens, suggesting a distinct pattern of innate immune system activation in PVL compared to OL, which may contribute to the complexity and the high rate of malignant transformation in the PVL.

Proliferative verrucous leukoplakia (PVL) is a non-homogenous type of oral leukoplakia, characterized by multifocal white plaques, propensity to recur after treatment, with strong tendency towards malignant transformation. Interestingly, some studies show that, at initial stages, PVL may resemble oral lichen planus (OLP), potentially leading to misdiagnosis. A 52-year-old woman, with a previous OLP diagnosis, was referred to our service for implant installation and follow-up of OLP lesions. After clinicopathological re-evaluation, a diagnosis of PVL (early stage) was made, and a maxillary full-arch implant-supported prosthesis supported by implants was installed. After 6 years of follow-up, the patient developed squamous cell carcinoma around the implants. The current case emphasizes that PVL patients with oral lesions suggesting peri-implantitis or peri-implant mucositis deserve a more meticulous investigation.

Oral potentially malignant disorders (OPMD) are clinical presentations that carry an increased risk of cancer development. Currently, epithelial dysplasia grade is based on architectural and cytological epithelial changes and is used to predict the malignant transformation of these lesions. However, predicting which OPMD will progress to a malignant tumor is very challenging. Inflammatory infiltrates can favor cancer development, and recent studies suggest that this association with OPMD lesions may be related to the etiology and/or aggressive clinical behavior of these lesions. Epigenetic changes such as histone modifications may mediate chronic inflammation and also favor tumor cells in immune resistance and evasion. This study aimed to evaluate the relationship between histone acetylation (H3K9ac) and DNA damage in the context of dysplastic lesions with prominent chronic inflammation. Immunofluorescence of “low-risk” and “high-risk” OPMD lesions (n = 24) and inflammatory fibrous hyperplasia (n = 10) as the control group was performed to assess histone acetylation levels and DNA damage through the phosphorylation of H2AX (γH2AX). Cell co-culture assays with PBMCs and oral keratinocyte cell lines (NOK-SI, DOK, and SCC-25) were performed to assess proliferation, adhesion, migration, and epithelial–mesenchymal transition (EMT). Oral dysplastic lesions showed a hypoacetylation of H3K9 and low levels of γH2AX compared to control. The contact of dysplastic oral keratinocytes with PBMCs favored EMT and the loss of cell–cell adhesion. On the other hand, p27 levels increased and cyclin E decreased in DOK, indicating cell cycle arrest. We conclude that the presence of chronic inflammation associated to dysplastic lesions is capable of promoting epigenetic alterations, which in turn can favor the process of malignant transformation.

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Background: Lichenoid and granulomatous stomatitis (LGS) is a rare condition, with clinicopathological features resembling lichenoid and granulomatous dermatitis. Despite increasing reports, its etiology remains unclear and detailed immunohistochemical (IHC) studies are lacking. Methods: We analyzed three new LGS cases, comparatively assessed with six cases each of oral lichen planus (OLP), oral lichenoid lesion (OLL), and oral leukoplakia (OL) showing lichenoid infiltrate. Histopathologic patterns were classified using the modified Magro & Crowson system, and IHC analysis included lymphocyte subsets, macrophages, and dendritic cells. Statistical comparisons were performed using Kruskal–Wallis with Dunn's post hoc test. Results: All LGS cases showed lymphohistiocytic infiltrates, microgranulomas, and perivascular/perineural lymphohistiocytic aggregates. IHC analysis revealed that LGS showed a significantly larger amount of macrophages (CD11c+/CD68+/CD163+) indicating M1/M2 equilibrium, CD3+ and CD8+ T‐cells, FOXP3+ regulatory T‐cells, and submucosal dendritic cells (FXIIIA+/CD209+) when compared to OLP/OLL/OL. Langerhans cells (CD1a+/CD207+) were similarly observed, whereas CD20+ B‐cells were scarce. Conclusions: This study provides the first comprehensive IHC analysis of LGS, highlighting distinctive macrophage, T‐cell, and dendritic cell profiles. These findings contribute to understanding LGS pathogenesis, support its diagnostic distinction, and suggest potential immunotherapeutic targets.