Histochemical analysis of pathological alterations in oral lichen planus and oral lichenoid lesions

Mast cells and factor XIIIa+ dendrocytes in actinic cheilitis and lip squamous cell carcinoma

There is an interaction between dendrocytes and mast cells in the skin. However, in elastosis-related diseases such as actinic cheilitis (AC) and lower lip squamous cell carcinoma (LLSCC), this interaction remains unknown. We investigated the presence of intact and degranulated mast cells in AC and LLSCC. Associations of mast cells with factor XIIIa+ dendrocytes and inflammatory infiltrate were assessed. Forty cases of AC (20 with low-grade and 20 with high-grade epithelial dysplasia), 50 cases of LLSCC, and 10 cases of normal oral mucosa were evaluated. Toluidine blue staining was performed to identify mast cells, and mast cell densities were calculated in the inflammatory infiltrate. Factor XIIIa+ dendrocytes were immunohistochemically quantified. The highest ratio of intact/degranulated mast cells density was detected in LLSCC (5.9 cells/mm2), followed by AC with high-grade epithelial dysplasia (4.8 cells/mm2). Statistically significant differences were found in the density of intact mast cells compared to degranulated mast cells in AC with low-grade epithelial dysplasia (p<0.001), AC with high-grade epithelial dysplasia (p=0.005), and LLSCC (p<0.001). A positive correlation between degranulated mast cells and total inflammatory infiltrate (p=0.03) was observed in the LLSCC group. The expression of factor XIIIa+ dendrocytes was highest in AC with low-grade epithelial dysplasia (16.5 cells/mm2). The link between mast cell density, factor XIIIa+ dendrocytes, and inflammatory infiltrate indicates a potential crosstalk in lip carcinogenesis.

Hydroxychloroquine is effective in oral lichen planus: A multicenter, randomized, controlled trial

OBJECTIVES

This study was aimed to evaluate the safety and benefit of short-term application of hydroxychloroquine in the management of atrophic/erosive/ulcerative oral lichen planus (OLP).

METHODS

This multicenter, randomized, controlled, evaluator-blinded, prospective clinical trial was performed from October 1, 2019, to September 1, 2022. A total of 99 patients were randomized to receive systemic use of hydroxychloroquine (n = 50), or topical use of 0.05% dexamethasone (n = 49) for 4 weeks. The response to both treatment modalities was evaluated according to reticulation, hyperemic, and ulceration (RHU) score and visual analog scale (VAS) score.

RESULTS

After 4 weeks of medication, both groups showed substantial reduction in RHU and VAS score (p < 0.05). In hydroxychloroquine group, the average of RHU score was reduced from 10.60 to 7.68 (dropped 27.49%), and the average of VAS score was reduced from 3.74 to 2.47 (dropped 34.09%). There were no differences between the two groups in reduction of RHU score and VAS score (p > 0.05). Single factor analysis found hyperemic area (p = 0.019) and erosive/ulcerative area (p = 0.024) had impacts on drug efficacy of hydroxychloroquine, and logistic regression revealed that no factors (p > 0.05) influenced its efficacy.

CONCLUSION

These findings indicate hydroxychloroquine is a safe and effective agent in treating atrophic/erosive/ulcerative OLP.

Mast cells in oral lichen planus and oral lichenoid lesions related to dental amalgam contact

The aim of this study was to analyze the expression of mast cell markers toluidine blue, c-kit, and tryptase and presence of mononuclear inflammatory cells in oral lichen planus (OLP) and oral lichenoid lesions related to dental amalgam. Nineteen specimens of OLP, OLLC, and healthy oral mucosa were selected. Mononuclear inflammatory cells were analyzed. Histochemical and immunohistochemical analyses were performed using toluidine blue, anti-c-kit and anti-tryptase reagents, and the results were quantified in areas A and B of connective tissue. Mast cells of all OLP and OLLC samples were positive for toluidine blue, c-kit, and tryptase. The density of toluidine blue+, c-kit+ and tryptase+ mast cells was higher in tissue with OLP and OLLC compared with healthy controls (p < 0.05). No difference was noted in mast cells density between OLP and OLLC (p > 0.05). The density of tryptase+ mast cells was higher in the subepithelial region (area A) than the region below it (Area B) in OLLC (p = 0.047). The mononuclear inflammatory cell density was higher in OLLC compared to OLP, but without statistical significance (p > 0.05). A positive statistical correlation was found between mononuclear immune cells and density of c-kit+ and tryptase+ mast cells in OLP (r = 0.943 and r = 0.886, respectively). Our data demonstrate that the etiopathogenesis process of OLP and OLLC modulates the expansion and degranulation of mast cells; mast cells density, however, was similar between OLP and OLLC. The distribution of mast cells appears to vary along the lamina propria.

Updates on immunological mechanistic insights and targeting of the oral lichen planus microenvironment

Oral lichen planus (OLP) is a chronic immune inflammatory disease that is an oral potentially malignant disorder (OPMD), occurs in the oral mucosa and affects approximately 0.5% to 4% of the general population. There are usually five types of OLP: reticular/papular, plaque-like, atrophic/erythematous, erosive/ulcerative, and bullous. Furthermore, the chance of causing oral squamous cell carcinoma (OSCC) is 1.4%. Although the etiology of OLP is still unknown, accumulating evidence supports that immune dysregulation may play a vital role in the pathogenesis of OLP, especially the massive production of various inflammatory cells and inflammatory mediators. In this review, we focus on the relationship between OLP and its immune microenvironment. We summarize current developments in the immunology of OLP, summarizing functional cell types and crucial cytokines in the OLP immune microenvironment and the underlying mechanisms of key signaling pathways in the OLP immune microenvironment. We highlight the application potential of targeted immune microenvironment therapy for OLP.

Oral Immune-Related Adverse Events Caused by Immune Checkpoint Inhibitors: Salivary Gland Dysfunction and Mucosal Diseases

Conventional chemotherapy and targeted therapies have limited efficacy against advanced head and neck squamous cell carcinoma (HNSCC). The immune checkpoint inhibitors (ICIs) such as antibodies against CTLA-4, PD-1, and PD-L1 interrupt the co-inhibitory pathway of T cells and enhance the ability of CD8+ T cells to destroy tumors. Even in advanced HNSCC patients with recurrent diseases and distant metastasis, ICI therapy shows efficiency and become an effective alternative to conventional chemotherapy. However, as this therapy releases the immune tolerance state, cytotoxic CD8+ T cells can also attack organs and tissues expressing self-antigens that cross-react with tumor antigens and induce immune-related adverse events (irAEs). When patients with HNSCC are treated with ICIs, autoimmune diseases occur in multiple organs including the skin, digestive tract, endocrine system, liver, and respiratory tract. Treatment of various malignancies, including HNSCC, with ICIs may result in the appearance of oral irAEs. In the oral cavity, an oral lichenoid reaction (OLR) and pemphigoid develop. Sicca syndrome also occurs in association with ICIs, affecting the salivary glands to induce xerostomia. It is necessary to elucidate the pathogenic mechanisms of these intractable diseases that are not seen with conventional therapy. Early diagnosis and appropriate approaches to irAEs are needed for efficient treatment of advanced HNSCC by ICIs.

Metal Allergy Mediates the Development of Oral Lichen Planus via TSLP-TSLPR Signaling

Metal allergy is a T-cell-mediated delayed type of hypersensitive reaction. The pathogenetic mechanisms underlying the allergy are unclear, although the condition has been reported to be related to oral lichen planus (OLP), despite an absence of immunological studies to support this relationship. In this study, histopathological samples of OLP patients were examined to compare the metal allergy-positive and -negative groups, with a focus on the network of epidermal keratinocytes and T cells induced by thymic stromal lymphopoietin (TSLP) and its receptor, TSLPR. Infiltration of T cells into the epithelium was revealed to be higher in the OLP lesions of metal allergy-positive patients than in those of metal allergy-negative patients. Moreover, TSLP-TSLPR signaling and TNF-α production were higher in the epithelial tissue samples of the metal allergy-positive patients than in the metal allergy-negative patients. Metal allergy is associated with both increased expressions of TSLP in keratinocytes and increased TNF-α levels in the epithelium. We propose that this would promote the accumulation of T cells at the lesion site, contributing to the formation of the disease. These results suggest that metal allergy may be an aggravating factor in the pathogenesis of OLP.

A machine-learning algorithm for the reliable identification of oral lichen planus

BACKGROUND

Oral lichen planus (OLP) is a relatively common oral disorder which shares clinical and histopathological features with other lichenoid lesions, leading to considerable inter-observer disagreement. This negatively impacts understanding of the pathogenesis and malignant transformation potential of this condition.

METHODS

Artificial intelligence was employed to create a machine-learning artificial neural network to identify and quantify mononuclear cells and granulocytes within the inflammatory infiltrates in digitized hematoxylin and eosin microscopic slides. Twenty-four regions of interest were extracted from OLP cases for learning purposes and validated on a retrospective cohort of 130 cases. All cases were related to patients with confirmed diagnoses of OLP, oral lichenoid lesions (OLLs), or oral epithelial dysplasia (OED) with lichenoid host response.

RESULTS

The number of inflammatory cells was statistically significantly higher in OLP compared to OLLs or OED with lichenoid host response (p < 0.0005). The proposed machine-learning method was reliably capable of detecting OLP cases based on the number of inflammatory cells and the number of mononuclear cells with an area under the curve of 0.982 and 0.988, respectively. Identifying a cut-off point between OLP and other lichenoid conditions based on the number of mononuclear cells showed a sensitivity of 100% and an accuracy of 94.62%.

CONCLUSION

Artificial intelligence has shown promising outcomes and provides a robust approach to enhance the accuracy of anatomical pathologists in accurately diagnosing OLP using features of disease pathogenesis.

Observer agreement in the diagnosis of oral lichen planus using the proposed criteria of the American Academy of Oral and Maxillofacial Pathology

BACKGROUND

Oral lichen planus (OLP) is a common chronic inflammatory condition with an undefined malignant transformation potential. There have been many attempts at providing a specific definition of OLP without conclusive outcomes. A new set of diagnostic criteria was proposed in 2016 by the American Academy of Oral and Maxillofacial Pathology (AAOMP) in an endeavour to resolve this issue, and this has not yet been evaluated. This study aimed to assess the utility of AAOMP proposed criteria for the diagnosis of OLP.

METHODS

Five pathologists blindly assessed a cohort of 215 digital whole slide images (WSI) obtained from haematoxylin and eosin-stained microscopic slides. Forty-six WSI were included twice to assess the intra-observer agreement. Included cases were diagnosed clinically as either OLP or oral lichenoid reaction. Each pathologist was asked to utilize the AAOMP histopathological criteria while assessing slides. The variations in diagnoses were assessed by unweighted kappa statistics.

RESULTS

The level of intra-observer agreement was very good (0.801 to 0.899). The level of inter-observer agreement among the observers varied from good (0.658) to very good (0.842) when the responses were categorized as evident/compatible OLP versus no OLP and was good (0.62 to 0.725) when the responses were categorized as evident OLP, versus compatible OLP, versus no OLP. The clinico-pathological correlation was 87.6%.

CONCLUSION

A reliable level of agreement can be achieved by pathologists for the diagnosis of OLP using the AAOMP criteria for differentiation between lichenoid and other conditions. There are still limitations in discriminating OLP from oral lichenoid lesions microscopically.

Histopathologic evaluation of oral lichen planus and oral lichenoid reaction: A comparative analysis based on basement membrane thickness and the distribution of mast cells

Background:

Lichen planus is a chronic mucocutaneous disease of unknown etiology with well-established clinical and microscopic features. Oral lichenoid reactions are a family of lesions triggered by contact with specific agents such as metallic restorative materials, resins and drugs. Oral lichenoid reactions share clinical and histological features of oral lichen planus (OLP) but has varied management options. Hence, the discrimination between these two lesions is a major challenge for clinicians as well as pathologists.

Aim:

Histopathologic categorization of OLP and oral lichenoid reaction by comparing the thickness of basement membrane and the distribution of mast cells using special stains.

Materials and Methods:

The test group consists of formalin-fixed paraffin-embedded blocks of OLP (n = 15), and oral lichenoid reactions (n = 15) obtained from the archives of the Department of Oral Pathology, Amrita School of Dentistry. Three serial sections of 4 μm thickness were cut from each block. The sections were stained with H & E, periodic acid-Schiff (PAS) and toluidine blue, respectively.

Results:

A significant increase in the maximum basement membrane thickness (BMT) was noticed in OLP when compared to oral lichenoid reaction. A definite increase was also noticed in the number of mast cells in OLP and oral lichenoid reaction when compared to normal oral mucosa. There was a statistically significant increase in the number of degranulated mast cells in the deeper connective tissue in oral lichenoid reaction when compared to OLP.

Conclusion:

OLP and oral lichenoid reactions are two different entities showing similar clinical and microscopic presentation. The histochemical analysis of basement membrane and mast cells in these lesions might provide a more authentic method for differentiating these two lesions and might be of utmost value in deciding the treatment options.

Histopathological features of oral lichen planus and its response to corticosteroid therapy: A retrospective study

Oral lichen planus (OLP) exhibits variations in severity and response to corticosteroid therapy. This study aims to assess the histopathological features of OLP at the time of diagnosis and their relationship in response to corticosteroid therapy.In this retrospective study, OLP patients were selected if a histopathological report was available. Data were collected regarding patients' demographics and medical history. Clinical and histological data were also obtained. The outcomes were histopathological findings, clinical form of OLP, number of exacerbations per year, and the response to corticosteroid therapy.In this study, 100 OLP patients were enrolled. Basal layer hydropic degeneration and band-like subepithelial lymphocytes infiltrate were observed in all patients. Plasma cells, identified in 62% of OLP patients, were significantly associated with fewer disease exacerbations and better response to corticosteroid treatment.Identifying histopathological features that may affect the clinical course would be clinically helpful in tailoring patient management.

Hawley retainer and lichenoid reaction: a rare case report

BACKGROUND

Oral lichenoid reaction (OLR) is a type IV cell-mediated immune response in the oral cavity. There is an established relationship between various dental materials and OLR, but few cases reports reported the occurrence of a lichenoid reaction in association with the use of a Hawley retainer.

CASE PRESENTATION

A female patient (twenty years of age) has been complaining of a reddish painful area on the tongue, which started one year ago and has been increasing in size over time. The patient completed orthodontic treatment two years ago and has been using a Hawley retainer for orthodontic retention since then. After performing histological analysis and patch test, the lesion was diagnosed as a lichenoid reaction to the Hawley retainer. Topical corticosteroids were prescribed, and the patient was asked to stop using the retainer and followed for six months.

CONCLUSIONS

It is difficult to diagnose lichenoid lesions and even more challenging to differentiate between OLP and OLR, therefore it is essential to do a full intraoral and extraoral examination. OLL can occur in association with Hawley retainer, which we believe could be because it is made of an acrylic based material. Generally, OLL resolves after removal of the cause.

Mast cell expression in oral lichen planus: A systematic review

Lichen planus is a common chronic, inflammatory, immune-mediated mucocutaneous disorder affecting the skin and mucosa. The role of mast cells in the genesis of lichen planus has been debated. Establishing a definitive part played by mast cells and its degranulation would possibly provide a permanent, cost-effective treatment modality for oral lichen planus (OLP). This review aims to study the expression of mast cells qualitatively and quantitatively in OLP. The research questions were framed to assess the mast cell count, localization within the epithelium basement membrane zone and degranulation of mast cells. We performed a systematic search of PubMed, Medline, Cochrane and Web of Science. We found a total of 120 studies from which 12 were found suitable for the review. There is a marked increase in the number of mast cells in OLP. The mast cells were seen in increased numbers in the epithelial and connective tissue junction at areas of basement membrane disruption. There was also an increase in the degranulation of mast cells. It is evident that there is an increase in the mast cell number in lichen planus and its subsequent degranulation.

Oral lichen planus: a literature review and update

Lichen planus (LP) is a common chronic inflammatory condition that can affect skin and mucous membranes, including the oral mucosa. Because of the anatomic, physiologic and functional peculiarities of the oral cavity, the oral variant of LP (OLP) requires specific evaluations in terms of diagnosis and management. In this comprehensive review, we discuss the current developments in the understanding of the etiopathogenesis, clinical-pathologic presentation, and treatment of OLP, and provide follow-up recommendations informed by recent data on the malignant potential of the disease as well as health economics evaluations.

[Immunomorphology of oral lichen planus]

The article is devoted to immunohistochemical study of reticular and erosive forms of oral lichen planus. Morphological examination of the reticular form revealed the increased number of Langerhans cells (CD1a), mast cells (CD25) and T lymphocytes (CD4, CD8, CD16) in the oral epithelium. Activation of these cells leads to the secretion of TNF-α and destruction of basal keratinocytes, which manifests as a focal reduction of intercellular protein expression of E-cadherin. Destruction of basal keratinocytes in a reticular form of oral lichen planus is accompanied by a significant decrease in proliferative activity of the basal cell layer (21.7±10.2%) compared with normal mucosa (33.6±7.0%), p=0.0045. In erosive form along with the above changes IgG and C3d complement's elements are revealed, which confirms the activation of immune complex mechanisms in the erosion area.

Oral lichen planus to oral lichenoid lesions: Evolution or revolution

The diagnosis between different diseases may be impaired by clinical and histopathologic similarities, as observed in the oral lichen planus (OLP) and oral lichenoid lesion (OLL). Inspite of similar clinicopathological features; etiology, diagnosis and prognosis differ which mandates separation of OLL from OLP. Hence, it is essential for the oral physician and oral pathologist to be familiarized with the individual variations among clinicopathological features of OLP and OLL as well as to obtain a thorough history and perform a complete mucocutaneous examination in addition to specific diagnostic testing. The difficulties faced to establish the diagnosis between these two pathologies are widely investigated in the literature with a lack of definite conclusion. This review is an attempt to throw some light on these clinicopathologic entities with the aim to resolve the diagnostic dilemma.

Oral lichenoid lesion: A review of the literature

The oral lichenoid lesion (OLL) is response that occurs on the oral mucosa. The OLL include allergic response to the dental materials, drugs, and on graft-vs-host disease (GVHD). OLL to dental material happen when restorative materials, most commonly amalgam, are in direct contact with the mucosa in sensitized individuals. Medications that produce OLL are oral hypoglycemic agents, angiotensin-converting enzyme inhibitors, and nonsteroidal anti-inflammatory agents. GVHD is a complication in bone marrow transplantation and OLL is a common lesion observed in this disease especially in chronic GVHD. The clinical and histological aspects of OLL are similar to oral lichen planus and turn it difficult to make a differential diagnosis. The purpose of this paper is review about OLL related to the dental materials, drug use and GVHD.

Oral lichenoid lesions - a review and update

Background:

Oral lichenoid lesions or reactions (OLLs/OLRs) are clinical and histological contemporaries of the classical oral lichen planus (OLP) that have generated a lot of debate in literature. In contrast to the idiopathic nature of OLP, OLLs are often associated with a known identifiable inciting factor. A superficial examination of these lesions clinically and histologically often reveals many similarities with OLP, but recent data indicate that distinguishable features do exist and form the basis of most classifications.

Aims and Objectives:

This paper attempts to collate available data in English literature on OLLs, highlight distinguishing features clinically and histologically and reflect on the malignant transformation potential and treatment modalities of the condition.

Materials and Methods:

A comprehensive search of medical and dental databases including PubMed, Ovid, Cochrane, Pubget, Researchgate, and non-medical search engines were utilized for the review. The search words included “oral lichen planus”, “oral lichenoid lesions”, “oral drug reactions”, “lichenoid dysplasia”, and “adverse effects of dental materials”.

Review Results:

OLLs seem to grossly underrated and most cases were clubbed as OLP. Definite clinical and histological features were uncovered to establish the identity of this lesion. Associations with dental restorative materials, drugs, and medications have been conclusively proven in the etiology of this condition. Specific markers are being utilized to diagnose the condition and monitor its progress.

Conclusion:

Substantial differentiating features were uncovered to delineate OLLs as a separate entity with definite etiology, pathogenesis, and a high malignant transformation rate compared with OLP.

Clinicopathologic correlation of oral lichen planus and oral lichenoid lesions: a preliminary study

Oral lichen planus (OLP) and oral lichenoid lesions (OLL) are clinically and histologically similar lesions but their treatment planning and prognosis are different. The review of the literature indicates numerous criteria to distinguish these two lesions; however there is a lot of inconsistency. Thus, the aim of this study was to determine the correlation of histopathology and clinical OLP and OLL diagnosis and to clarify which histopathologic criteria could best distinguish these two diagnoses. A retrospective study showed that clinically diagnosed 92 OLPs and 14 OLLs have been confirmed histopathologically in 52.2% and 42.9% of cases, respectively. In addition, histopathology showed statistically significant more eosinophils (P<0.0005), plasma cells (P<0.0005), and granulocytes (P<0.05) in OLL than OLP. To establish histopathological diagnosis of OLP and OLL it should be mandatory to define the type of cells in mononuclear infiltrate, which can be associated more accurately with clinical feature and patient history. Therefore, currently accepted diagnostic criteria for OLP and OLL should be modified and validated on a larger number of patients taking into account particular distinguishing histopathological features.

Oral Lichenoid Lesions Related to Drugs: Review of Clinicopathological Features and Differential Diagnosis

Lichenoid drug reaction is termed as a condition of the oral cavity having an identifiable etiology, which is clinically and histologically similar to oral lichen planus. A number of drugs have been described as a causative factor of those reactive lesions. The aim of this study is to conduct a systematic review on the role of causative drugs in oral lichenoid lesions (OLLD) and the clinicopathological features of this entity which still has uncertainty in diagnosis. Bibliographic searches were carried out to identify articles published in English on PubMed® Online electronic databases from 1993 to 2013. Available clinical, histological and treatment methods were recorded. A total of 25 articles fulfilled the inclusion criteria with 37 patients. OLLD were detected frequently in patients with a history of zidovudine and imatinib mesylate medication. OLLD occurred significantly in subjects over the age of 30 (p<0.01), mostly on buccal mucosa (42.37%). The most preferable treatment is withdrawal of the drugs and administering a topical steroid regimen. Thirty OLLD cases were confirmed by biopsies which were characterized by diffuse inflammatory infiltrate through the deep side of the lamina propria. Medical history and histological features are the two basic criteria for the differential diagnosis of OLLD.

A retrospective comparative study on clinico-pathologic features of oral lichen planus and oral lichenoid lesions

Introduction:

Oral Lichen Planus (OLP) and Oral Lichenoid Lesions (OLLs) are clinically and histopathologically similar lesions but with different etiologies and treatment plan, thus differentiating these two has been the center of many researches. Studies in different populations have been performed on clinical and histopathologic features of OLP and OLLs. Thus aim of the present study was to evaluate and also compare the clinical and histopathologic features of these two diseases in a 10-year period in Esfahan.

Materials and Methods:

This descriptive–analytic study was based on retrospective survey of 232 records with clinical and histopathologic diagnosis of OLP and OLLs available from archive of oral pathology, Esfahan dental school 2000-2010. Data was statistically analyzed by use of independent t-test, Fisher exact, and Chi-square.

Results:

Involvement of lip was the only clinically significant difference between OLP and OLLs, most seen in OLLs. Band-like inflammatory infiltrate mainly composed of lymphocyte, saw toothed rete ridges, Max Joseph space, and atrophic epithelium was significantly seen in OLP. While hyperkeratosis, deep connective tissue infiltrate composed of eosinophil, neutrophil, and plasma cell were seen in OLLs.

Conclusion:

Involvement of lip was the only clinically significant difference between OLP and OLLs. Histopathologically strict band like infiltration, atrophic epithelium, saw toothed rete ridges, and Max Joseph space are reliable criteria for differentiation of OLP as deep connective tissue infiltration and hyperparakeratosis are for diagnosis of OLLs.

Evaluation of Serum TNF-α and TGF-β in Patients with Oral Lichen Planus

Background and aims

The role of cytokines in the immunopathogenesis of oral lichen planus (OLP) has received much attention. The aim of this study was to evaluate the serum levels of TNF-α and TGF-β in patients with OLP in an Iranian population.

Materials and methods

Thirty-two patients with OLP and 32 age-matched healthy volunteers as a control group were included in this study. Serum tests including TNF-α and TGF-β was performed in both groups. Data analysis was performed using descriptive statistics and Mann–Whitney U test using SPSS software version 16.0.

Results

The mean of TNF-α in study and control groups were 157 ± 115 pg/ml and 14 ± 10 pg/ml, respectively. The difference between the two means was statistically significant (P < 0.001). Moreover, the mean of TGF-β in study and control groups were 155 ± 26 pg/ml and 175 ± 57 pg/ml, respectively. The difference between the two means was statistically significant (P = 0.03).

Conclusion

According to the results of the present study, there was a significant decrease in the serum levels of TGF-β and a significant increase in the serum levels of TNF-α in patients with oral lichen planus. The increase in TNF-α serum levels in patients with OLP explains the inflammatory process in the course of the disease.

Mast cells distribution and variations in epithelium thickness and basement membrane in oral lichen planus lesion and oral lichenoid reaction

Background:

Oral lichen planus (OLP) is a chronic mucocutaneous lesion with unknown etiology. Oral lichenoid lesions (OLL) comprise a family of lesions with different etiologies. Both lesions have similar clinical and histopathologic characteristics although their management is different. Differential diagnosis between OLP and OLL has always been a major challenge.

Materials and Methods:

In this prospective analytical study, the role of mast cells in pathogenesis of these lesions was investigated by evaluation of 52 patients with clinical and histopathological diagnosis of OLP (26 cases) and OLL (26 cases) based on WHO criteria, and by applying a more accessible staining methods, Hematoxylin and Eosin, toluidine blue (histochemistry) and Periodic Acid Schiff staining. In order to distinguish these two lesions, number of mast cells and thickness of epithelium and basement membrane were measured using light microscopy. Data were analyzed by SPSS software using t-test method (P<0.001).

Results:

No significant difference was observed between the total numbers of mast cells of two groups (P=0.148), but a statistically significant difference was detected between degranulated mast cells in two groups (P<0.001). A significant difference was also observed between the thickness of epithelium in two groups (P<0.001), although no difference was seen between basement membrane thickness in these lesions.

Conclusion:

Number of degranulated mast cells in reticular layer of corium in lichenoid lesions was more than that of OLP. This implies that despite the increase in number of these cells, in both groups of diseases, the role of these cells has not been the same in pathogenesis of the diseases. Moreover, the epithelium thickness was lower in lesions of OLP compared to lesions of oral lichenoid, so this parameter may be a useful criterion together with other histopathological and clinical finding to discriminate these lesions. However, discrepancy of basement membrane thickness can not be a reliable criterion. Finally we suggest more accessible staining methods which are reliable for differentiation of these two lesions.

Degranulated mast cells and TNF-α in oral lichen planus and oral lichenoid reactions diseases

Background:

The objective of this study was to assess mast cells and TNF-α in oral lichen planus (OLP) and oral lichenoid reactions (OLR) patients as diagnostic marker to the differential diagnosis of OLP and OLR diseases.

Materials and Methods:

In this cross-sectional study, samples were obtained from 30 OLP and 30 OLR patients, between June 2010 and March 2011 in Dental clinic of the University of Isfahan, Iran. Mast cells in the reticular layer of the lamina propria for samples were evaluated using toluidine blue method and immunohistochemical technique. The clinical relevant data taken into account were: demographical data, total number and degranulated mast cells, ratio of degranulated mast cells and TNF-α positive degranulated mast cells.

Results:

In OLP and OLR, the total mast cells were 21.2 ± 7.9 and 20.3 ± 6.8, degranulated mast cells were 15.5 ± 6.9 and 19.2 ± 6.9, ratio of degranulated mast cells to total mast cells were 0.716 ± 0.067 and 0.946 ± 0.081, and TNF-α positive degranulated mast cells were 13.6 ± 6.3 and 17.1 ± 6.04, respectively. There was no significant difference for the total mast cells. But degranulated mast cells, ratio of degranulated mast cells and TNF-α positive degranulated mast cells in OLR were significantly higher than OLP patients.

Conclusions:

Our results showed that the degranulated mast cells, ratio of degranulated mast cells and TNF-α in OLR was significantly more than OLP patients and these may be able to be used as diagnostic markers to the differential diagnosis of OLP and OLR.

Cys-X-Cys ligand 9 might be an immunological factor in the pathogenesis of oral submucous fibrosis and its concomitant oral lichenoid lesion

OBJECTIVES

Oral submucous fibrosis (OSF) is a chronic oral precancerous disease primarily caused by betel quid chewing. Some OSF patients are concomitant with oral lichenoid lesion (OLL), a white-streak lesion with a higher risk for cancerization, in OSF mucosa. Immunological reaction has been considered as one of their common pathogenic mechanisms. Cys-X-Cys ligand 9 (CXCL9) is an important factor to recruit effector neutrophils and lymphocytes in immunological reactions. However, the expression levels of CXCL9 in OSF and OLL remain unclear.

MATERIALS AND METHODS

We investigated the expression levels of CXCL9 in 10 normal buccal mucosa (NBM) samples and 56 OSF concomitant with OLL patients, and evaluated the possible mechanism of CXCL9 on their pathogenesis.

RESULTS

Our results showed NBM demonstrated negative CXCL9 expression. OSF stained positive CXCL9 mainly in the cytoplasm of inflammatory cells and endothelial cells throughout the superficial layer of connective tissue, while its concomitant OLL showed much stronger CXCL9 in all mononuclear cells of subepithelial inflammatory infiltration (p = 0.0006). There was an upregulated trend of CXCL9 expression from NBM to OSF to OLL. However, no significant association between CXCL9 expression and clinicopathologic parameters of patients was found.

CONCLUSIONS

In conclusion, CXCL9 was found for the first time to contribute to the immunological pathogenesis for both OSF and its concomitant OLL, indicating a continuously enhanced intensity of immunoreactivity in their pathogenic process.

CLINICAL RELEVANCE

CXCL9 might be a useful tool to monitor the phase and disease severity of OSF and OLL, and a potential target for further clinical therapy for both lesions.

Clinical and histologic healing of lichenoid oral lesions following amalgam removal: a prospective study

OBJECTIVE

This study aimed to see whether clinical healing after amalgam removal corresponds to histologic healing, i.e., a complete disappearance of any histologic sign of lichenoid lesion.

STUDY DESIGN

The study evaluated 64 patients with lichenoid lesions and at least one amalgam filling.

RESULTS

After amalgam removal, complete clinical healing was obtained in 14 patients (22%) and was significantly related to lesion topography (χ(2) 4.7; P < .05) and positive patch test (χ(2) 6.3; P < .01). Complete histologic healing was obtained in only 7 cases (50% of clinically healed patients), and was significantly related to the combination of positive patch test and strict contact with amalgams (Fisher's exact test P < .01).

CONCLUSIONS

Contact with amalgams and positive patch testing are good but not absolute indicators of the beneficial effect of amalgam replacement. In addition, complete clinical healing does not necessarily mean a disappearance of the histologic characteristics of OLL/OLP lesions.

Pathogenesis of oral lichen planus--a review

Oral lichen planus (OLP) is a T-cell-mediated chronic inflammatory oral mucosal disease of unknown etiology. OLP presents as white striations, white papules, white plaques, erythema, erosions, or blisters affecting predominantly the buccal mucosa, tongue and gingiva. Both antigen-specific and non-specific mechanisms are hypothesized to be involved in the pathogenesis of oral lichen planus (OLP). Antigen-specific mechanisms in OLP include antigen presentation by basal keratinocytes and antigen-specific keratinocyte killing by CD8(+) cytotoxic T cells. Non-specific mechanisms include mast cell degranulation and matrix metalloproteinase activation in OLP lesions. These mechanisms may combine to cause T cell accumulation in the superficial lamina propria, basement membrane disruption, intra-epithelial T cell migration and keratinocyte apoptosis in OLP. The various hypotheses proposed for pathogenesis of oral lichen planus are discussed in this review.

Oral lichenoid lesions in HIV-HCV-coinfected subjects during antiviral therapy: 2 cases and review of the literature

Some dental materials and certain drugs may induce epithelial alterations, which clinically resemble oral lichen planus (OLP), on oral mucosa. But these alterations do not have all the clinical and/or the histological features of OLP; these lesions are known as oral lichenoid lesions (OLLs). Some researchers describe the onset and/or the worsening of OLL/OLP after the administration of anti-hepatitis C virus (HCV) therapy. In this article, we describe the development of symptomatic OLLs, as a consequence of anti-HCV therapy (interferon-alpha and ribavirine), in 2 human immunodeficiency virus-HCV-coinfected subjects. An immunological cause related to coinfection and administration of different medications could be responsible for the onset of OLLs. These new cases, together with the previous reports of a possible association between OLP and/or OLL and anti-HCV therapy, highlight the absolute need to monitor carefully the human immunodeficiency virus-HCV-coinfected subjects who are about to start the anti-HCV therapy and to define better the clinical and histopathological criteria to distinguish OLP from OLL.