Increased mast cell density and protease content in actinic cheilitis

The emerging role of mast cells in skin cancers: involved cellular and molecular mechanisms

Skin cancers are the most common cancers worldwide. They can be divided into nonmelanoma skin cancers (NMSC) including basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and less common lymphomas and merkel cell carcinoma, and melanomas. Melanomas comprise less than 5% of skin cancer rate but are responsible for more than 90% of skin cancer death. Mast cells (MCs) are multifunctional cells that play an important role in inflammatory and allergic reactions. They attract other key players of the immune system by releasing cytokines. Healthy human skin comprises MCs under physiological status, and the number can increase under certain conditions including skin malignancies postulating their possible role in pathogenesis of and immunity against skin cancers. MCs respond to cytokines released by tumor stromal cells, release mediators (including histamine and tryptase), and induce the neovascularization, degradation of extracellular matrix (ECM), and induce mitogenesis. However, MCs may use molecular mechanisms to exert immunosuppressive activity including releasing complement C3, lower expression of CD40L, and overexpression of enzymes with vitamin D3 metabolizing activity including CYP27A1 and CYP27B1. This review summarizes the current knowledge on the role of MCs in pathogenesis and immunity against skin cancers.

Histopathological features of photodamage and mast cell infiltrate in actinic cheilitis with different grades of epithelial dysplasia

BACKGROUND

Actinic cheilitis is induced by chronic exposure to ultraviolet radiation and shows solar elastosis, a feature that has been associated with mast cell infiltrates. This study aimed to investigate the area of solar elastosis, collagen loss, and mast cell infiltrates in a series of actinic cheilitis.

METHODS

We evaluated the epithelial dysplasia in 52 cases of actinic cheilitis and the solar elastosis with Weigert's resorcin-fuchsin. Collagen loss was evaluated with Picrosirius red, analyzed under polarized microscopy, and scored from 1 to 3. Elastosis proportionate area (EPA) was calculated with image software. Mast cells were highlighted with toluidine blue stain.

RESULTS

EPA varied from 2% to 45%, with a mean of 17.1% in the cases, with no differences among epithelial dysplasia degrees. Most cases presented collagen loss scores of 2 or 3, and higher loss of type I collagen was associated with older age. Mast cell density was higher in severe epithelial dysplasia (P = 0.002) and in high-risk cases (P = 0.01).

CONCLUSION

Actinic cheilitis presented variable EPA and marked loss of type I collagen; however, these features were not associated with the degrees of epithelial dysplasia. Besides, mast cell density increased with epithelial dysplasia worsening and this was not associated with elastosis area or collagen loss.

HYBID (alias KIAA1199/CEMIP) and hyaluronan synthase coordinately regulate hyaluronan metabolism in histamine-stimulated skin fibroblasts

The immune-regulatory compound histamine is involved in the metabolism of the essential skin component hyaluronan (HA). We previously reported that histamine up-regulates the expression of HYBID (hyaluronan-binding protein involved in hyaluronan depolymerization, also called CEMIP or KIAA1199), which plays a key role in HA degradation. However, no information is available about histamine's effects on HA synthase (HAS) expression, the molecular sizes of HA species produced, and histamine receptors and their signaling pathways in skin fibroblasts. Moreover, histamine's effects on photoaged skin remain elusive. Here, we show that histamine increases HA degradation by up-regulating HYBID and down-regulating HAS2 in human skin fibroblasts in a dose- and time-dependent manner and thereby decreases the total amounts and sizes of newly produced HA. Histamine H1 blocker abrogated the histamine effects on HYBID up-regulation, HAS2 suppression, and HA degradation. Histamine H1 agonist exhibited effects on HA levels, composition, and breakdown similar to those of histamine. Of note, blockade of protein kinase Cδ or PI3K-Akt signaling abolished histamine-mediated HYBID stimulation and HAS2 suppression, respectively. Immunohistochemical experiments revealed a significant ∼2-fold increase in tryptase-positive mast cells in photoaged skin, where HYBID and HAS2 expression levels were increased and decreased, respectively, compared with photoprotected skin. These results indicate that histamine controls HA metabolism by up-regulating HYBID and down-regulating HAS2 via distinct signaling pathways downstream of histamine receptor H1. They further suggest that histamine may contribute to photoaged skin damage by skewing HA metabolism toward degradation.

Histomorphometric Comparative Analysis between Oral Dysplastic Potentially Malignant Disorders and Oral Squamous Cell Carcinoma

Objective This study aimed to determine the correlation between the vascular mast cells and inflammatory changes in the potentially malignant disorders, compared to the oral squamous cell carcinoma (OSCC) in varying degrees of dysplasia.

Materials and Methods Thirty samples were selected: 10 of OSCC, 10 of oral leukoplakia, and 10 of actinic keratosis. The toluidine blue technique was used on the mast cells, and hematoxylin and eosin were used for analyzing the lymphocytes, mitosis, and vessels. The quantification was performed using the ImageJ software after obtaining the images by light microscopy with a × 40 objective. Analysis of variance with p < 0.05 was considered for statistical significance.

Results Mast cells ( p < 0.0158), vessels ( p < 0.9431), lymphocytes ( p < 0.0001), and mitoses ( p < 0.0009) were found in OSCC. In potentially malignant disorders, a lower density of these structures and a higher concentration of mitosis in the actinic keratosis were observed.

Conclusion The results showed evidence of a positive correlation between mast cells and vascularization in the OSCC, suggesting the aggression of the disease. Intense inflammatory infiltrate indicates that other molecular events are involved in the carcinogenesis process, and further studies are necessary for a better understanding of it.

Melasma: Updates and perspectives

Management of melasma is highly challenging due to inconsistent treatment results and frequent relapses. However, recent studies revealed that melasma may not only be a disease of melanocytes, but also a photoaging skin disorder. Herein, we attempt to validate that melasma is indeed a photoaging disorder by presenting the histopathologic findings of melasma: solar elastosis, altered basement membrane, increased vascularization and increased mast cell count. We also provide some therapeutic implications based on these findings and a discussion on the latest updates and perspectives regarding treatment.

Ultraviolet radiation and skin mast cells: Effects, mechanisms and relevance for skin diseases

Mast cells (MCs) are well known as versatile effector cells in allergic reactions and several other immune responses. Skin MCs and cutaneous MC responses are subject to the effects of environmental factors including ultraviolet radiation (UVR). Numerous studies have assessed the effects of UVR on MCs, in vitro and in vivo. Interestingly, UVR seems to have variable effects on non-activated and activated mast cells. In general, UV therapy is beneficial in the treatment of urticaria and mastocytosis, but the effects are variable depending on treatment regimen and type of UVR. Here, we review and summarise key reports from the older and current literature on the crosstalk of UVR and skin MCs. Specifically, we present the literature and discuss published reports on the effects of UVR on skin MCs in rodents and humans. In addition, we review the role of MCs in UVR-driven skin diseases and the influence of UV light on MC-mediated skin diseases. This summary of our current understanding of the interplay of skin MCs and UVR may help to improve the management of patients with urticaria and other MC disorders, to identify current gaps of knowledge, and to guide further research.

Actinic cheilitis: proposition and reproducibility of a clinical criterion

Objectives/Aims:

The actinic cheilitis (AC) is a precancerous lip lesion seen as a consequence of chronic sun exposure. Clinically, the border between the lip’s skin and the semimucosa could be blurred; in the more aggressive cases, leucoplakia and ulcers also represent its clinical feature. It seems that no clinical criterion is universally accepted for this disease yet. Therefore, this study was carried out to make a proposition of a clinical score to actinic cheilitis (Grade I starting from dryness of vermilion to endured ulcers representing Grade IV) and to assess its reproducibility.

Materials and Methods:

Fifty subjects were assessed, most of whom were male, Caucasian farmers, with an average age of 46.12 (18–74) years. The obtained data were analysed by means of descriptive statistics and by Kappa test to assess the inter-examiners and the clinical Golden-Pattern concordance (95% CI).

Results:

During calibration, 15 patients were examined three times a week by each examiner (4) until Kappa test observed k=0.8 or more. In the main experiment, the inter-examiner concordance was classified between good (k=0.779; P<0.05) and very good (k=0.925; P<0.05) from the 35 examined subjects. With the Golden-Pattern, it was considered very good (k=0.812; P<0.05 to k=0.925; P<0.05).

Discussion:

Four examiners with different experiences could strongly suggest that after adequate calibration, it could be well applied by examiners with as much experience as a dental student.

Conclusions:

The authors concluded that the proposed classification was easily applied and had a very good reproducibility.

Acquired bilateral telangiectasia macularis eruptiva perstans: A unique clinical feature of photodamaging rather than a subtype of cutaneous mastocytosis

Telangiectasia macularis eruptiva perstans (TMEP) is a rare subtype of cutaneous mastocytosis, characterized by telangiectatic tan to brown macules on the trunk and extremities. Although TMEP has been descried as an uncommon disease in the literature, we often encounter patients with TMEP lesions in the outpatient clinic. We aimed to assess the clinical and histopathological characteristics of acquired bilateral TMEP, and the pathophysiological mechanism of acquired bilateral TMEP among these patients. We retrospectively reviewed 30 patients (28 men and 2 women) with acquired bilateral TMEP; multiple telangiectatic dark red to brown macules that were symmetrically distributed. The clinical characteristics and general histopathological findings of lesional skin were investigated. The number of mast cells was evaluated using immunohistochemical analysis with an antibody directed against c-kit (CD117). Acquired bilateral TMEP was predominantly localized on the sun-exposed area: the upper arm in 30 patients (100%), forearm in 19 patients (63.3%) and anterior chest in 15 patients (50%). A total of 16 patients (53.3%) showed at least one aggravating factor, including UV irradiation, alcohol use and heat exposure. Compared with the mast cell numbers in 19 age- and biopsy site-matched healthy controls (91 ± 29.0/mm² ), the number of mast cells in the papillary dermal skin of acquired bilateral TMEP patients was significantly increased (159 ± 37.2/mm² , P < 0.01). In addition, a significant difference in vessel numbers in the papillary dermis was observed between acquired bilateral TMEP patients and healthy controls (10.5 ± 1.9 vs 5.4 ± 1.0/mm² , P < 0.01). Acquired bilateral TMEP is a relatively common disorder in middle-aged Asian men. An increased number of mast cells and dilated vessels might be a photoaging-related reactive process of chronic sun-exposure, which consequently leads to the formation of characteristic telangiectatic hyperpigmentary macules through certain melanogenic mediators.

The clinical prevalence of actinic cheilitis among community health agents from the regional V subprefecture of Fortaleza

ABSTRACT Objective: The aim of this study was to evaluate clinically the prevalence of Actinic Cheilitis in community health agents from the Regional V subprefecture of Fortaleza. Methods: The sample consisted of 333 community health workers exposed to the sun on a daily basis. The community health agents were evaluated through a questionnaire (with information about the individual, their occupations and habits) and a clinical examination in the first stage of the study. In the second stage, the Actinic Cheilitis lesions were classified according to the degree of severity, monitored and treated as needed. Both stages were performed by just one examiner. The data were tabulated in an Excel spreadsheet and evaluated by means of the G-test. Results: The results showed that the prevalence of Actinic Cheilitis was significantly associated with age, race / color and use of lip balm. A total of 101 (30.3%) community health agents were found to have normal labial mucosa, 195 (58.5%) had a mild alteration in Actinic Cheilitis, 34 (10.2%) with moderate Actinic Cheilitis and in 3 (0.9%) severe change was identified. Conclusion: The study concluded that the prevalence of Actinic Cheilitis is high among the community health agents from the Regional V subprefecture of Fortaleza.

Mast Cells: Key Players in the Shadow in Oral Inflammation and in Squamous Cell Carcinoma of the Oral Cavity

Although mast cells (MCs) have been discovered over 130 years ago, their function was almost exclusively linked to allergic affections. At the time being, it is well known that MCs possess a great variety of roles, in both physiologic and pathologic conditions. In the oral tissues, MCs release different proinflammatory cytokines, tumor necrosis factor alpha (TNF-α), that promote leukocyte infiltration in various inflammatory states of the oral cavity. These cells play a key role in the inflammatory process and, as a consequence, their number changes in different pathologic conditions of the oral cavity, like gingivitis, periodontitis, and so on. MCs also represent a rich source of proteases, especially of mast cell tryptase and chymase, which directly degrade the extracellular matrix through their proteolytic activity and thus indirectly stimulate angiogenesis and facilitate invasion and metastasis. It may be stated that mast cells could have an impact on primary tumor development, progression, and metastases in oral squamous cell carcinoma. By understanding the role of mast cells in the pathogenesis of different inflammatory and tumor diseases of the oral cavity, these cells may become therapeutic targets that could possibly improve the prognosis and survival of these patients.

CD8+ and FoxP3+ T-cell infiltration in actinic cheilitis

BACKGROUND

Differences in immune profile between actinic cheilitis (AC), a precursor of lip squamous cell carcinoma, and normal lip vermillion (NL) have not been elucidated.

OBJECTIVES

To compare density, distribution, and ratios of CD8+ and FoxP3+ cells between AC and NL and assess their associations with clinicopathologic variables.

METHODS

Samples of AC and NL obtained between 2001 and 2013 at the College of Dentistry of the University of Concepcion, Chile, were retrospectively analyzed for immunohistochemical detection of CD8+ and FoxP3+ cells. Differences between groups were tested by Mann-Whitney U and Fisher's exact tests. Independent effects of cell densities and CD8/FoxP3 ratio with AC were assessed by multiple logistic regression analysis after adjustment for potential confounding.

RESULTS

A total of 62 AC and 24 NL biopsies were included. Densities of CD8+ and FoxP3+ cells in AC were significantly higher than in NL. Conversely, the CD8+/FoxP3+ ratio was significantly lower in AC as compared to NL. After adjustment for sun exposure, age, gender, and smoking status, a stromal FoxP3+ cell density higher than 0.35 cells/field was significantly associated with increased odds of AC (odds ratio [OR] = 5.01, 95% confidence interval [CI]: 1.18-21.31), while a stromal CD8+/FoxP3+ ratio higher than 5.91 was associated with decreased odds of AC (OR = 0.29, 95% CI: 0.08-1.08).

CONCLUSIONS

AC is characterized by increased FoxP3+ cell infiltration and a reduced CD8/FoxP3 ratio as compared to NL. Therefore, increased infiltration of FoxP3+ cells relative to CD8+ cells may contribute to the transition from normal to preneoplastic stages in lip carcinogenesis.

Heterogeneous Pathology of Melasma and Its Clinical Implications

Melasma is a commonly acquired hypermelanosis that affects sun-exposed areas of the skin, with frequent facial involvement. Its histologic manifestations are evident in the epidermis, extracellular matrix, and dermis. In addition to epidermal pigmentation, pathologic findings of melasma include extracellular matrix abnormality, especially solar elastosis. The disrupted basement membrane has been described in melasma with variable incidences. In the dermis, an increase in vascularity and an increase in the number of mast cells were observed, indicating that dermal factors have critical roles in the pathogenesis of melasma, despite the fact that melasma is characterized by epidermal hyperpigmentation. This review discusses such histologic characteristics of melasma, with consideration to their implications for melasma treatment.

Queilite actínica: avaliação histopatológica de 44 casos

Objetivo: Descrever os aspectos epidemiológicos, clínicos e histopatológicos da queilite actínica. Material e método: Foi realizado um estudo retrospectivo a partir de casos com diagnóstico clínico de queilite actínica, registrados no arquivo histopatológico do Serviço de Cirurgia de Cabeça e Pescoço do Hospital Napoleão Laureano, Paraíba, relativos ao período de 2000 a 2007. Foram selecionados 44 blocos parafinados, que apresentavam condições de reavaliação histológica através da confecção de novas lâminas. Os novos cortes foram corados em Hematoxilina e Eosina, e a avaliação histopatológica foi realizada por dois examinadores independentes, sendo as alterações classificadas de acordo com OMS. Realizou-se análise estatística descritiva em programa SPSS for Windows versão 13. Resultado: Do total da amostra, 52,3% (23) dos casos foram diagnosticados em homens e 47,7% (21) em mulheres, com idade variando de 27 a 92 anos. A maioria dos indivíduos (81,9%) tinha mais de 40 anos. Em relação às características histológicas, 68,2% (30) dos casos exibiram algum grau de displasia epitelial, sendo 36,3% (16) classificados como displasia leve, 20,4% (9) como displasia moderada e 11,3% (5), displasia severa. Em 15,9% (7), ocorreu carcinoma de células escamosas. No tecido epitelial de revestimento labial, os achados histológicos mais frequentes e identificados foram presença de degeneração hidrópica (79,5%) e hipergranulose (56,8%). Infiltrado inflamatório foi observado em 88,6% dos casos e elastose solar, em 86,4%. Conclusão: Com base nos resultados da amostra estudada, podemos concluir que a maioria das lesões de queilite actínica acometeu lábio inferior de homens, com mais de 40 anos de idade. A análise histopatológica revelou displasia e atipia celular, infiltrado inflamatório e presença de elastose solar, que são características comuns em lesões de QA.

Regulatory T cells in the actinic cheilitis

BACKGROUND

Actinic cheilitis (AC) is an oral potentially malignant lesion which is the counterpart of actinic keratosis of the skin and has potential to develop into squamous cell carcinoma. Regulatory T cells (Tregs) have a critical role in modulating the antitumor immune responses. The presence of regulatory T cells in potentially malignant lesions has not been described. We chose investigate the involvement of regulatory T cells in potentially malignant lesions.

METHODS

The frequency, phenotype, and activity of CD4+CD25+ T cells isolated from blood and lesion of AC patients were analyzed by flow cytometry. Cytokines were quantified by ELISA. Data were compared with samples from healthy subjects.

RESULTS

The frequency and suppressor activity of circulating CD4+CD25+ T cells was similar in AC patients and control subjects. However, the frequencies of IL-10-positive Tregs were higher in AC patients, and these cells inhibited interferon-gamma (IFN-γ) and increased interleukin (IL)-10 productions in co-cultures. Furthermore, CD4+CD25+ T cells accumulate in AC lesions. Lesions-derived regulatory T cells suppressed lymphocyte proliferation and pro-inflammatory cytokine production. Moreover, high levels of IL-10 and transforming growth factor-β (TGF-β), and low IFN-γ were detected in the potentially malignant lesions.

CONCLUSION

Therefore, our data show that Tregs accumulate in AC lesions, and these cells could be suppressing immune responses in a potentially malignant microenvironment.

Expression of matrix metalloproteinases 9 and 12 in actinic cheilitis

AIM: To investigate the role of matrix-degrading metalloproteinases 9, 12 (MMPs), as mediators of functional connective tissue damage in actinic cheilitis.

METHODS: Thirty five formalin-fixed, paraffin embedded specimens of actinic cheilitis, and twelve specimens of normal lower lip vermillion, which were obtained by the archives of the Department of Oral Medicine and Maxillofacial Pathology, were examined. From each block, 5 μm thick sections were cut and routinely stained with Hematoxylin and Eosin. Immunohistochemical studies were performed on 4-μm thick sections of formalin-fixed paraffin embedded actinic cheilitis lesions and of normal lower lip vermillion, for MMP-9 and MMP-12 in serial sections of our specimens. Appropriate positive and negative controls were performed to confirm the specificity of the staining reaction. MMP immunohistochemistry was evaluated using a semiquantitative immunoreactive score.

RESULTS: Haematoxylin and eosin staining revealed in actinic cheilitis lesions atrophic stratified squamous cell epithelium, or focally and irregularly hyperplastic of variable thickness, in some areas was observed marked keratin production. Varying degrees of epithelial dysplasia were noticed with a wide spectrum of change within the same specimen. Characteristic was the appearance of chronic inflammatory infiltration, and a band of amorphous acellular, basophilic change like solar elastosis (elastin replacement of collagen). In normal lower lip specimens weak and scanty positive expression of MMP-9 and MMP-12 was observed. Anti-MMP-9 antibody showed a weak reaction, in actinic cheilitis lesions, focal in the elastotic material, in chronic inflammatory cells and mostly in macrophages and neutrophils. Strong and in some cases diffused immunohistochemical expression of MMP-12 was detected in actinic cheilitis lesions in the areas of the fragmented, distorted and thickened elastic fibers. MMP-12 was also expressed in chronic inflammatory cells and mostly macrophages. MMP-12 was significantly higher in actinic cheilitis specimens compared with the normal lower lip specimens (P = 0.0029).

CONCLUSION: Our results suggest that especially MMP-12 may play an important role in remodeling events occurring in the connective tissue during long-term exposure to sunlight in the actinic cheilitis lesions.

Mast cells and matrix metalloproteinase 9 expression in actinic cheilitis and lip squamous cell carcinoma

OBJECTIVES

The aim of this study was to evaluate mast cell (MC) density and migration and their association with matrix metalloproteinase (MMP) 9 expression in squamous cell carcinoma (SCC) and actinic cheilitis (AC).

STUDY DESIGN

Tryptase, c-Kit, and MMP-9 expression was evaluated in 20 cases of SCC, 20 cases of AC, and 7 cases of normal lip (control samples) by immunohistochemistry techniques.

RESULTS

Tryptase(+) and c-Kit(+) MC densities were significantly higher in SCCs than in ACs and control samples (P < .001). However, no significant difference was found when comparing tryptase(+) and c-Kit(+) MC densities between ACs and control samples (P values .185 and .516, respectively). MMP-9 was strongly expressed in SCCs and moderately expressed in ACs and control samples. A highly significant association was found between tryptase(+) MC density and the expression of MMP-9 (P < .001).

CONCLUSIONS

The increase in MC density associated with the strong expression of MMP-9 may favor SCC progression.

Altered β-catenin expression related to cancer progression on actinic cheilitis and squamous cell carcinoma of the lip

β-Catenin is a bifunctional protein related to cell adhesion and gene transcription when activated by Wnt pathway. Altered expression of β-catenin was related to loss of differentiation, more aggressive phenotype, increase of tumor invasion, and poor prognosis in a number of different cancers. Actinic cheilitis is caused by excessive exposure to ultraviolet radiation and has a high potential to suffer malignant transformation into squamous cell carcinoma (SCC) of the lip, the most frequent oral malignancy. Studies of oral cancer have shown the correlation of β-catenin expression and oral SCC prognosis, and loss of membrane expression may be considered as a potential marker for early tumor recurrence. Thirty-five cases of actinic cheilitis and 12 cases of SCC of the lip were select and submitted to immunohistochemical staining using β-catenin antibody. β-Catenin was positive on the membrane for all cases. Eighty-five percent of actinic cheilitis cases showed cytoplasmatic staining, and 22% nuclear staining. Eighty-three percent of SCC was positive for β-catenin, and none of them had nuclear staining. Cytoplasmatic and nuclear staining of β-catenin on studied cases point to pathway alterations. Results demonstrated that β-catenin expression is altered on epithelial dysplasia, and it is related to degree of alterations.

Actinic cheilitis: clinical and histological features

PURPOSE

The purpose of this study was to analyze the clinical and histological features of actinic cheilitis (AC).

PATIENTS AND METHODS

A total of 29 patients with AC were clinically evaluated, and incisional biopsies were performed to confirm the clinical diagnosis. Histological features were analyzed, and dysplasia was classified as mild, moderate, or severe. The chi(2) test was used for the following variables: gender, age, race, and smoking habits. The degree of dysplasia was related to these variables (Fisher's test) to test for independence between them (P < .05).

RESULTS

Of the patient group, 72.41% were male, 75.86% were over age 40 years, 93.10% were white, and 72.41% were nonsmokers. Clinically, all patients presented with multifocal lesions. The following manifestations were seen: dryness, atrophy, scaly lesions, swelling of the lip, erythema, ulceration, blurred demarcation between the lip vermilion border and the skin, marked folds along the lip vermilion, white spots or plaques, crusts, blotchy areas, and areas of pallor. Keratosis, granulosis, hyperplasia, acanthosis, or atrophy and dysplasia were found in the epithelial tissue; elastosis, inflammatory infiltrate, and vasodilatation were found in the connective tissue. Dysplasia was mild in 10.34% of the patients, moderate in 27.59%, and severe in 62.07%. Absence of sample homogeneity was observed in regard to gender, age, race, and smoking habits. It was not possible to reject the hypothesis of independence between mild, moderate, or severe dysplasia and gender, age, race, and smoking habits.

CONCLUSIONS

Dryness, atrophy, and scaly lesions were the most common clinical findings observed. Dysplasia, inflammatory infiltrate, and vasodilatation, as well as elastosis, were the most common histological findings observed. Gender, age, race, or smoking habits were not related to the degree of dysplasia in the sample.

Comparative analysis of the mast cell density in normal oral mucosa, actinic cheilitis and lip squamous cell carcinoma

Previous studies have shown that the number of mast cells is increased in ultraviolet (UV) irradiated skin and in neoplasias. Actinic cheilitis (AC) is a lesion caused by excessive exposure to sunlight that can transform into lip squamous cell carcinoma. The aim of this study was to compare the number of mast cells in 4 groups: NOM = normal oral mucosa (n=6); MDAC = mild dysplasia in actinic cheilitis (n=13); SDAC = severe dysplasia in actinic cheilitis (n=13); and LSCC = lip squamous cell carcinoma (n=15). The sections were stained by histochemical technique of blue toluidine and visual counting was performed with the aid of a reticulum coupled to the microscope ocular. A calibrated observer performed the count in 5 fields by case at ×400 magnification. The largest mean number of mast cells per group was observed in LSCC (40.1), followed by MDAC (30.5), SDAC (28.6) and NOM (12.2). There were significant differences between NOM and MDAC (p<0.05) and between NOM and LSCC (p<0.05). The increased density of mast cells observed in AC and in LSCC compared to NOM suggests a role for the mast cells in the development of these lesions.

Characterization of mast cell subpopulations in lip cancer

BACKGROUND

Lip squamous cell carcinoma (SCC) is the most common form of oral cancer. Human mast cells (MCs), which are increased in lip SCC, are classified by their protease content in tryptase-positive (MC(T)) and tryptase/chymase-positive (MC(TC)). MC proteases are associated with tumor progression and angiogenesis. The aim of this study was to quantify and characterize MC subpopulations in lip SCC.

METHODS

Serial sections from lip SCC (n = 21) and normal lip vermilion (n = 8) biopsies were stained immunohistochemically for tryptase and enzymehistochemically for chymase to determine MC subpopulation density and distribution.

RESULTS

MC(T) and MC(TC) were increased in lip SCC when compared with normal lip (P < 0.0001), where MC(T) predominated over MC(TC) (P < 0.01). In lip SCC neither subpopulation predominated. Regarding distribution, MC(T) were higher than MC(TC) at the intratumoral stroma, whereas MC(TC) were higher than MC(T) at the peritumoral stroma (P < 0.01).

CONCLUSIONS

The results suggest that MC subpopulations may contribute to lip SCC progression. While intratumoral MC(T) may stimulate angiogenesis, peritumoral MC(TC) may promote extracellular matrix degradation and tumor progression at the invasion front.