Oral squamous cell carcinoma in relation to field precancerisation: pathobiology (original) (raw)
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Pattern of keratinization in oral squamous cells during carcinogenesis
Background: Oral carcinogenesis is a multi-step process. Broadly, oral squamous cell carcinoma (OSCC) can be well-, moderately- or poorly-differentiated, and either keratinizing or non-keratinizing. Most cases are moderately to poorly-differentiated. Precursor lesions (dysplasia) can be categorized into mild, moderate, or severe (carcinoma in situ).In the present study, the pattern of keratin expression in oral squamous cells during carcinogenesis is vividly analysed. Materials and Methods: Samples in the form of scraped and exfoliated cytosmear were collected from the affected sites of the clinically diagnosed 136 oral cancer patients and were immediately fixed in acetoalcohol (1:3). The wet fixed smears were stained by routine Papanicolaou’s staining protocol and Giemsa’s solution. Stained tissues were studied under the microscope. Results: Cytological pleomorphism is a unique feature observed during carcinogenesis. There appears to be a spectrum of degrees of keratinization rather than distinct types, and the degree of keratinization is reflected in the degree of packing and orientation of keratin filaments. It is presumed that alteration in the architectural regularity of the cell membrane is an important aspect of keratinization which leads to cytological pleomorphism during oral carcinogenesis. Conclusion: Pattern of keratinization alongwith cytological pleomorphism in exfoliated epithelial squamous cells has a practical utility in the diagnosis and early detection of oral cancer during carcinogenesis. Keywords: Carcinogenesis, Keratinization, Keratins, Oral squamous cell carcinoma.
Histological and molecular aspects of oral squamous cell carcinoma (Review)
2014
Oral squamous cell carcinoma (OSCC) represents 95% of all forms of head and neck cancer, and over the last decade its incidence has increased by 50%. Oral carcinogenesis is a multistage process, which simultaneously involves precancerous lesions, invasion and metastasis. Degradation of the cell cycle and the proliferation of malignant cells results in the loss of control mechanisms that ensure the normal function of tissues. The aim of the current review is to present the histopathological features of OSCC, including potentially malignant changes, the international classification of tumors, the tumor invasion front and tumor biomarkers (Ki-67, p53, homeobox genes and collagen type IV), as well as the tumor microenvironment and function of cancer-associated fibroblasts in the most common type of oral cancer that is encountered by dental surgeons. In OSCC, associations have been identified between the proliferation, basal lamina degradation and connective tissue modulation. Therefore, the comparison of these factors with the survival time of OSCC patients from the histopathological diagnosis is of interest
Preneoplasia and carcinogenesis of the oral cavity
Oral cancer, ranking sixth in the cancer incidence worldwide, is one of the most common neoplasms. Preneoplastic or premalignant (precancerous) lesions are lesions that can potentially transform into malignancy in a variety of tissues, including the oral cavity. Such oral lesions may be caused by tobacco use, exposure to the human papillomavirus and chewing of the betel nut. These substances contain carcinogens and/or tumor promoters. The mucosa of the oral cavity is covered with squamous epithelium and is relatively resistant to injury. However, exposure to these substances can cause the mucosa to undergo changes. The changes are usually initiated by a leukoplakic patch. While some leukoplakic patches recover and resolve, others progress to squamous cell carcinoma with or without invasion. Other premalignant lesions include oral submucous fibrosis, which is a potentially malignant condition caused by the abuse of the betel nut. Understanding the histology, premalignant states and molecular mechanisms of oral carcinogenesis may facilitate the development of novel strategies for the prevention and treatment of oral cancer. In addition, early detection is of critical importance to improve the survival rates of patients with oral cancer. In this review, we will summarize these aspects of oral cancer development, beginning from the histology of the oral cavity.
Oral Medicine & Pathology, 2003
Carcinomas of the oral cavity sometimes arise as multiple, independent lesions and this observation has led to the concept of field cancerization. Howerever, the mechanism of multiple occurrences of oral squamous cell carcinoma (OSCC) is still unknown. Thirty-one cases of synchronous and/or metachronous multiple OSCCs were selected from biopsy and operation materials of the Dental Hospital, Tokyo Medical and Dental University. Histopathogenetic study and investigation were carried out. The clonality of the tumor tissues was analyzed by immunohistochemistry for Ki-67, Bcl-2, p53, cyclinB1 and cyclinD1. Histologic observation showed two patterns of occurrence of OSCC: de novo type and premalignancy-associated type. Twenty-one patients with multiple OSCCs were classified into 3 groups. Group I was de novo type, Group II was mixed type and Group III was premalignacy-associated type. Seventeen of 21 patients (80.9%) revealed p53-positivity in the epithelium apart from the tumor. Fifty-two of 69 tumors (75.4%) showed a different expression rate between Cyclin B1 and Cyclin D1. This data suggests that those patients are at high risk of developing second primary tumors. It also suggests the possibility of polyclonal development of the multiple OSCCs.
The behaviour of human oral squamous cell carcinoma in cell culture
The Journal of Pathology, 1990
This study examined the initial behaviour of48 human oral squamous cell carcinomas (SCC) in cell culture. The early outcome of these cultures (contamination, absence of cell growth. epithelial cell senescence/fibroblast overgrowth, extended keratinocyte growth) did not reflect the clinical characteristics of the tumours of origin. Four new human oral SCC cell lines were characterized more extensively. Each cell line was immortal. 3T3-independent. and expressed low degrees of anchorage independence (CFE < 4 per cent). Two of the four cell lines were tumorigenic in athymic mice. All of the cell lines expressed keratin intermediate filaments and two showed weak co-expression of vimentin. A wide range of keratins were expressed by the tumour xenografts; cornified keratins (K I , K 10) were only expressed in the absence of K 19 and vimentin. and vice versa. The nuc1ear:cytoplasmic ratio and the degree of serum independence correlated with cach other and with the STNMP clinical grading of the tumours of origin. KEY WORDS-Human oral carcinoma cell lines. squamous cell carcinoma, cell culture. immunohistochemistry.
The pathology of oral cancer and precancer
Current Diagnostic Pathology, 1996
Oral cancer is the sixth most common cancer worldwide and represents about 5.5% of all malignancies. In the Western world it is less common, but the incidence is increasing and the mortality rate has not improved for decades. Although most oral cancers probably arise in clinically normal mucosa some are preceded by a precancerous lesion which indicates an increased risk of cancer development at a particular site. The histopathologist's role is to recognize pathological features which indicate high risk and to provide prognostic information from examination of excised tumours. The most common precancerous lesion is a white patch on the oral mucosa referred to as a leukoplakia. These show variable clinical features ranging from relatively innocuous fiat white plaques to verruciform or red and white speckled lesions.
Molecular Biology of Oral Squamous Cell Carcinoma
2020
Squamous cell carcinomas (SCCs) appear as firm tan or white tumors on gross examination. On histopathology, SCC is classified into well, moderate, and poorly differentiated by the level of squamous differentiation. Well-differentiated SCC has prominent intercellular bridges, dyskeratotic squamous cells, and keratin pearls. Poorly differentiated SCC has minimal squamous differentiation morphologically and needs of immunohistochemistry for confirmation of the diagnosis. Cytokeratin 5/6, p63, and p40 are useful immunohistochemical markers to confirm squamous differentiation in these cases. Moderately differentiated SCC shows evidence of squamous differentiation in a smaller proportion of the tumor than well-differentiated SCC. Grading of SCC does not significantly impact prognosis.
World Journal of Dentistry
Aim: Squamous cell carcinoma is the most common malignancy affecting the oral cavity. In spite of advanced therapeutic interventions, it is still a common cause of morbidity and mortality worldwide. The clinical presentation and prognosis of the carcinomas occurring at different sites in the oral cavity is varied and could be explained by the difference in the type of epithelia from which they originate. Therefore this study aimed to assess the patient and tumor characteristics, clinical presentation and behavior of a sample of oral squamous cell carcinomas (OSCC) to determine the parameters most likely to influence the prognosis based on the origin of the epithelium. Materials and methods: Eighty-nine cases of histologicallyproven oral squamous cell carcinoma with a minimum followup of three years were categorized based on their epithelia of origin. The clinical follow-up data and survival were collected from the patient's records. New malignancy grading by Anneroth et al. was utilized for histopathological grading following which the lymph nodes (in cases of neck dissection) were assessed for evidence of nodal metastasis. Results: Most of the carcinomas originated from the nonkeratinized epithelium (42.7% n = 38) followed by the keratinized epithelium. Carcinomas arising from the non-keratinized epithelium had the poorest outcome with a mortality of 27.7% (n = 10) and disease-free survival of 38.8% (n = 14) at the end of 36 months. Conclusion: The present study though limited in its sample size and follow-up concluded that the nature of epithelium of origin has a bearing on the prognosis of oral squamous cell carcinoma. Clinical significance: Knowledge of the prognostic significance of the oral squamous cell carcinomas based on the type of epithelia of origin will help the clinicians to plan a more aggressive treatment plan for patients with carcinomas originating from the non-keratinized epithelium.
UNIVERSITY JOURNAL OF DENTAL SCIENCES
Oral carcinogenesis is known as multifactorial process which engaged plentiful genetic events that transform normal activity of tumor suppressor genes and oncogenes. It is observed that aggregation of genetic alterations is the ground for advancement of a normal cell to cancer cells, which is known as a multi-step carcinogenesis. Because of this event, growth factor production increases as well as increase in total of receptors on cell surface and increased intracellular signal messengers. The present review scrutinize the existing documentation in the literature related to the oral squamous cell carcinoma. English language articles were searched in various databases such as Pubmed, Scopus, Science direct and Google scholar. The keyword used for searching are “oral squamous cell carcinoma”, “Genetics and Oral squamous cell carcinoma”,“Molecular mechanism in oral squamous cell carcinoma”. The present review spotlights on understanding the molecular mechanism and the genetic factors ...
Uncommon features in conventional oral squamous cell carcinoma
Journal of Oral and Maxillofacial Pathology, 2016
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