The use of discriminant analysis for examining the histological feathers of oral keratoses and lichen planus

Prediction of malignant transformation and recurrence of oral epithelial dysplasia using architectural and cytological feature specific prognostic models

Oral epithelial dysplasia (OED) is a precursor state usually preceding oral squamous cell carcinoma (OSCC). Histological grading is the current gold standard for OED prognostication but is subjective and variable with unreliable outcome prediction. We explore if individual OED histological features can be used to develop and evaluate prognostic models for malignant transformation and recurrence prediction. Digitised tissue slides for a cohort of 109 OED cases were reviewed by three expert pathologists, where the prevalence and agreement of architectural and cytological histological features was assessed and association with clinical outcomes analysed using Cox proportional hazards regression and Kaplan-Meier curves. Within the cohort, the most prevalent features were basal cell hyperplasia (72%) and irregular surface keratin (60%), and least common were verrucous surface (26%), loss of epithelial cohesion (30%), lymphocytic band and dyskeratosis (34%). Several features were significant for transformation (p < 0.036) and recurrence (p < 0.015) including bulbous rete pegs, hyperchromatism, loss of epithelial cohesion, loss of stratification, suprabasal mitoses and nuclear pleomorphism. This led us to propose two prognostic scoring systems including a '6-point model' using the six features showing a greater statistical association with transformation and recurrence (bulbous rete pegs, hyperchromatism, loss of epithelial cohesion, loss of stratification, suprabasal mitoses, nuclear pleomorphism) and a 'two-point model' using the two features with highest inter-pathologist agreement (loss of epithelial cohesion and bulbous rete pegs). Both the 'six point' and 'two point' models showed good predictive ability (AUROC ≥ 0.774 for transformation and 0.726 for recurrence) with further improvement when age, gender and histological grade were added. These results demonstrate a correlation between individual OED histological features and prognosis for the first time. The proposed models have the potential to simplify OED grading and aid patient management. Validation on larger multicentre cohorts with prospective analysis is needed to establish their usefulness in clinical practice.

Oral epithelial dysplasia: Recognition, grading and clinical significance

Histopathological grading of epithelial dysplasia remains the principal laboratory method for assessing the risk of malignant transformation in oral potentially malignant disorders (OPMDs). Current views on the molecular pathogenesis and histological interpretation of the features of epithelial dysplasia are described, and the use of grading systems for epithelial dysplasia is discussed. Changes to the current 2017 WHO criteria for diagnosis are proposed with emphasis on the architectural features of epithelial dysplasia. The predictive values of three-grade and binary systems are summarised, and categories of epithelial dysplasia are reviewed, including lichenoid and verrucous lesions, keratosis of unknown significance, HPV-associated dysplasia, differentiated and basaloid epithelial dysplasia. The implications of finding epithelial dysplasia in an oral biopsy for clinical management are discussed from the pathologists' viewpoint.

Oral epithelial dysplasia: Classifications and clinical relevance in risk assessment of oral potentially malignant disorders

After more than a decade, the World Health Organization (WHO) published the revised grading system for oral epithelial dysplasia in 2017. The revised classification has changes reflecting our evolution of understanding of the dysplastic process. Although the WHO 2017 three-tier grading system is the gold standard for histological diagnosis of oral potentially malignant disorders, it has certain limitations. Suggestions to overcome these limitations include the use of clinical determinants and molecular markers to supplement the grading system. It has also been suggested that a two-tier system may be more reproducible and clinically translatable for better management. These advances in the understanding of epithelial dysplasia are very important globally and for us in the Indian subcontinent, given the prevalence of habits (tobacco/areca nut) and burden of oral cancer in this part of the world. The following review traces the evolution of the grading system of dysplasia, its relevance and clinical utility.

Quantitative Exfoliative Cytology of Abnormal Oral Mucosal Smears

In this study quantitative techniques have been applied to smears collected from the buccal mucosa and floor of the mouth. The results display an encouraging success rate for identifying premalignant and malignant lesions. ‘Intrapatient’ normal smears provide a satisfactory control for comparison with pathological smears. Early results indicate that quantitative cytology could be of great value for monitoring and follow-up of suspicious lesions and provide an excellent additional diagnostic test for detecting early oral malignancy.

Upregulation of epidermal growth factor receptor 4 in oral leukoplakia

In the present study, we investigate the expression profile of the epidermal growth factor receptor family, which comprises EGFR/ErbB1, HER2/ErbB2, HER3/ErbB3 and HER4/ErbB4 in oral leukoplakia (LP). The expression of four epidermal growth factor receptor (EGFR) family genes and their ligands were measured in LP tissues from 14 patients and compared with levels in 10 patients with oral lichen planus (OLP) and normal oral mucosa (NOM) from 14 healthy donors by real-time polymerase chain reaction (PCR) and immunohistochemistry. Synchronous mRNA coexpression of ErbB1, ErbB2, ErbB3 and ErbB4 was detected in LP lesions. Out of the receptors, only ErbB4 mRNA and protein was more highly expressed in LP compared with NOM tissues. These were strongly expressed by epithelial keratinocytes in LP lesions, as shown by immunohistochemistry. Regarding the ligands, the mRNA of Neuregulin2 and 4 were more highly expressed in OLP compared with NOM tissues. Therefore, enhanced ErbB4 on the keratinocytes and synchronous modulation of EGFR family genes may contribute to the pathogenesis and carcinogenesis of LP.

An Insight to Oral Epithelial Dysplasia

Oral dysplasia is a potentially precancerous lesion diagnosed histologically. While the risk of progression is associated with histological grade, it is currently impossible to predict accurately which lesions will progress. Although most oral pathologists recognize and accept the criteria for grading epithelial dysplasia based on architectural and cytological changes, there can be considerable interexaminer and intraexaminer variation in the assessment of the presence or absence and the grade of oral epithelial dysplasia. This article reviews the alterations, criteria, different grading systems and the markers used for assessing the malignant transformation of epithelial dysplasia.

How to cite this article

Rastogi V, Puri N, Mishra S, Arora S, Kaur G, Yadav L. An Insight to Oral Epithelial Dysplasia. Int J Head Neck Surg 2013;4(2):74-82.

Grading oral epithelial dysplasia: analysis of individual features

BACKGROUND

Assessing epithelial dysplasia to predict malignant transformation remains problematic in many tissues because grading systems are poorly structured and individual features poorly defined. Dysplasia grading is criticised for lack of reproducibility and poor predictive value. Grading systems for upper aerodigestive tract dysplasia have evolved over several decades and are not supported by good outcome experimental data.

METHODS

 This study analysed the individual features of dysplasia in 86 oral dysplastic lesions and determined the reproducibility of scoring for each, and correlated them with other features and clinical factors using complex clustering analyses.

RESULTS

A uniform pattern of dysplasia was found in 37 lesions, focal dysplasia in 36 and in 13 lesions dysplasia formed complex discontinuous patterns. There was wide variation in reproducibility of scoring of individual features and many, including thickness, some types of rete morphology, basaloid cell anisonucleosis, basal dyscohesion, and dyskeratosis as deep single cells correlated with sub-sites. Rete morphology, type of keratinisation, hyperchromatism of the basaloid compartment, prickle cell anisonucleosis and extension down salivary ducts correlated with smoking. Conventional grading and oral intraepithelial neoplasia (OIN) grading by 'thirds affected' showed strong correlation overall but scores obtained with the OIN system tended to a higher grade at all sites except soft palate/fauces. There was poor correlation between the systems for moderate dysplasia and also severe dysplasia at some sites. Individual features could not be shown to cluster to form distinct patterns of dysplasia.

CONCLUSIONS

These variations may account in part for the lack of reproducibility and poor predictive value of the grading systems in current use and could inform the design of future grading systems.

Impact of betel quid, tobacco and alcohol on three-stage disease natural history of oral leukoplakia and cancer: implication for prevention of oral cancer

The natural history of the three-stage process from normal, oral leukoplakia to oral cancer in relation to betel quid chewing, smoking and drinking is rarely addressed. The aim of this study was to simultaneously quantify the effects of three risk factors on occurrence of oral leukoplakia and malignant transformation to oral cancer. A hospital-based case-control study design derived from three retrospective cohorts from 1988 to 1998 was conducted. A total of 74 oral cancer patients, 164 patients with oral leukoplakia and 187 controls were interviewed to collect information on their betel chewing, smoking and drinking habits. The effects of the three risk factors on the progression rates of the three-stage disease process were estimated using the three-state Markov model. Subjects who chewed betel quid were at greater risk of leukoplakia (adjusted odds ratio (OR) 17.7 (9.03-34.5)) but there was no significant effect on malignant transformation (OR 1.04 (0.61-1.76)). Smoking played a major role in the onset of leukoplakia (OR 4.26 (2.21-8.23)) but a minor role in malignant transformation (OR 1.36 (0.69-2.68)). Alcohol was positively associated with malignant transformation (OR 2.37 (1.47-3.82)) but unrelated to occurrence of leukoplakia (OR 0.76 (0.04-1.43)). We concluded that smoking and betel quid were two significant risk factors for the occurrence of leukoplakia, whereas alcohol was significantly responsible for malignant transformation.

Quantification of the global and local complexity of the epithelial-connective tissue interface of normal, dysplastic, and neoplastic oral mucosae using digital imaging

This study aimed at quantifying the complexity of the epithelial-connective tissue interface (ECTI) in human normal mucosa, premalignant, and malignant lesions using fractal geometry. Two approaches were used to describe the complexity of 377 oral mucosa ECTI profiles. The box counting method was used to estimate their global fractal dimension, while local fractal dimensions were estimated using the mass radius relation at various local scales. The ECTI complexity significantly increased from normal through premalignant to malignant profiles in both global and local (over 283 microm) scales. Normal mucosa samples from different sites of the oral cavity also had different degrees of global complexity. Fractal geometry is a useful morphological marker of tissue complexity changes taking place during epithelial malignancy and premalignancy, and we propose it as a quantitative marker of epithelial complexity.

Prognosis of oral pre-malignant lesions: significance of clinical, histopathological, and molecular biological characteristics

The concept of a two-step process of cancer development in the oral mucosa, i.e., the initial presence of a precursor subsequently developing into cancer, is well-established. Oral leukoplakia is the best-known precursor lesion. The evidence that oral leukoplakias are pre-malignant is mainly derived from follow-up studies showing that between < 1 and 18% of oral pre-malignant lesions will develop into oral cancer; it has been shown that certain clinical sub-types of leukoplakia are at a higher risk for malignant transformation than others. The presence of epithelial dysplasia may be even more important in predicting malignant development than the clinical characteristics. Three major problems, however, are attached to the importance of epithelial dysplasia in predicting malignant development: (1) The diagnosis is essentially subjective, (2) it seems that not all lesions exhibiting dysplasia will eventually become malignant and some may even regress, and (3) carcinoma can develop from lesions in which epithelial dysplasia was not diagnosed in previous biopsies. There is, therefore, a substantial need to improve the histologic assessment of epithelial dysplasia or, since epithelial dysplasia does not seem to be invariably associated with or even a necessary prerequisite for malignant development, it may be necessary to develop other methods for predicting the malignant potential of pre-malignant lesions. As a consequence of these problems, numerous attempts have been made to relate biological characteristics to the malignant potential of leukoplakias. Molecular biological markers have been suggested to be of value in the diagnosis and prognostic evaluation of leukoplakias. Markers of epithelial differentiation and, more recently, genomic markers could potentially be good candidates for improving the prognostic evaluation of precursors of oral cancer. As yet, one or a panel of molecular markers has not been determined that allows for a prognostic prediction of oral pre-cancer which is any more reliable than dysplasia recording. However, these new markers could be considered complementary to conventional prognostic evaluation.

Increased fractal complexity of the epithelial-connective tissue interface in the tongue of 4NQO-treated rats

The effect of the carcinogen 4-nitroquinoline 1-oxide (0.001% in drinking water) on the irregularity of the epithelial connective tissue interface (ECTI) of the ventral surface of the tongue was quantified in Dark Agouti and Wistar Furth rats. Histological tongue sections stained with the Azan-Mallory method were digitised (111 images, resolution 1 pixel = 3.1 microns), and the limit between epithelium and stroma of the ventral surface was extracted and analysed using a fractal geometry technique (local connected dimension). The results showed that although none of the images included carcinomas on the ventral surface of the tongue (all cases had other oral carcinomas), the epithelial profiles of the treated cases showed a statistically significant increase in irregularity when compared to controls. Canonical discriminant analysis of the parameters describing the irregularity of the ECTI classified 81.1% of the images in the original groups (treated or control). Fractal analysis is capable of detecting subtle architectural changes in the oral epithelium of the rat occurring after exposure to the carcinogen, even when full malignant transformation has not yet taken place. Fractal analysis, which may prove useful for monitoring the progression of carcinogenesis in this animal model, is a morphometrical parameter in the diagnosis of oral epithelial dysplasia.

How important is tumour shape? Quantification of the epithelial-connective tissue interface in oral lesions using local connected fractal dimension analysis

Quantification of the local complexity of the epithelial-connective tissue interface (ECTI) in normal mucosa, epithelial dysplasia, and squamous cell carcinoma of the floor of the mouth was investigated by estimating the local connected fractal dimension in tissue profiles from histological sections. The use of certain parameters of the distribution of the local connected fractal dimensions of the ECTI classifies the cases belonging to these three histopathological diagnoses with 85 per cent accuracy by means of linear discriminant analysis. The values of the local fractal dimension were also used to produce colour-coded dimensional images of the ECTI, to highlight locations with higher irregularity that may correlate with locally invasive 'higher-risk' areas.

Nuclear morphometry in squamous cell carcinoma (SCC) of the tongue

In the histological grading of oral squamous cell carcinoma (OSCC) nuclear features are very important. Nevertheless evaluation is usually performed in a subjective and not highly reproducible way. The aim of this work was to investigate the relationship between nuclear shape and survival in 30 cases of carcinoma of the tongue. All the patients were divided into two groups: short-term survival and long-term survival. Twenty nuclei for each tumour were submitted to a morphometrical study by the shape analytical morphometry (SAM) software system. It was thus possible to evaluate not only nuclear dimensions but also nuclear contour irregularities and nuclear shape asymmetries. Multivariate discriminant analysis (MDA) of the quantitative parameters obtained by the morphometrical study distinguished the patients of the two groups with only a 10% error; moreover successful cluster analysis was performed by using Fourier parameters. Both these sets of results were achieved mainly owing to the parameters for contour irregularities.

Intraexaminer and interexaminer reliability in the diagnosis of oral epithelial dysplasia

OBJECTIVES

Pathologists differ in their definition of "dysplasia." This study was done to test the hypothesis that experienced oral pathologists are consistent in diagnosing epithelial dysplasia.

STUDY DESIGN

Six board-certified oral pathologists examined 120 oral biopsies exhibiting simple hyperkeratosis to severe dysplasia. No clinical information was given, and presence of dysplasia was judged by histomorphology. Examiners' diagnoses were compared with sign-out diagnoses for each case. Months later, each examiner viewed 60 relabeled slides from the original 120. Each diagnosis was compared with the diagnosis in the first round.

RESULTS

Exact agreement with the sign-out diagnosis averaged 50.5% (within one histologic grade 90.4%). Examiners agreed exactly with their own diagnoses 50.8% of the time (within one histologic grade 92.4%). Agreement distinguishing dysplasia from no dysplasia compared with original sign-out diagnosis was 81.5%. Agreement with themselves distinguishing dysplasia from no dysplasia was 80.3%.

CONCLUSIONS

Accurate reproducible agreement among experienced board-certified oral pathologists diagnosing oral epithelial dysplasia is difficult to achieve.

Preliminary assessment of the epithelial nuclear-cytoplasmic ratio and nuclear volume density in human palatal lesions

We have analysed both the nuclear-cytoplasmic (N/C) ratio and nuclear volume densities (VVN) in defined strata from human hard palate lesions with and without malignant potential to determine the prognostic reliability and/or validity of this parameter. Measurements of cellular and nuclear areas of basal and spinous cells from normal (N) and pathological palatal epithelium were made on histological sections using an image analyser. The lesions comprised fibrous hyperplasia (FH), traumatic inflammation (INF), benign hyperkeratosis (HK), squamous cell papilloma (PP), dysplastic epithelium adjacent to invasive carcinoma (CE) and islands of invasive squamous cell carcinoma (CI). In basal cells, no significant differences were detected in comparisons of N/C and VVN between all pathological groups and the N control group. The mean value for CE was lower than that obtained for N. In spinous cells, the only statistically significant comparison was between IF and FH for both N/C and VVN. Both parameters were lower in CE than in N. Of all groups analysed except CI, the CE group is the only one likely to possess an increased malignant potential. The N/C ratio therefore seems to be of no value as a predictor of malignancy in palatal epithelial lesions.

Basal cell nuclear size in experimental oral mucosal carcinogenesis

It has been suggested that the size of the nuclei of epithelial basal cells can be used in predicting the likelihood of malignant transformation of epithelium. This proposition was assessed in rat palatal epithelium after the carcinogen 4-nitroquinoline-1-oxide had been applied to the epithelium for varying periods of time. No consistent alterations in basal cell nuclear size, including area, perimeter, diameter and regularity of form were found with routine light microscopy as the epithelium passed through various stages of dysplasia to carcinoma. This finding casts doubt on the value of using a variation of basal cell nuclear size as a predictor of malignant transformation.

Quantification of oral epithelial hyperplasia in rats after topical application of the carcinogen 4-nitroquinoline 1-oxide

Hyperplasia of the palatal epithelium was quantified in two groups of rats exposed thrice weekly to the carcinogen 4NQO for 2 weeks and 2 months, respectively. The lengths and areas of the epithelial layers were measured with a computerized line-following device. In the group treated for 2 weeks the maximum area of the nuclear layer was nearly three times and the maximum length of the epithelial/connective tissue interface almost twice the normal at the end of the carcinogen application period. The maximum area of the cornified layer was three times and the maximum lengths of the epithelial surface and the keratin/nuclear layer interface almost one and a half times the normal 1 week after painting with 4NQO. Thereafter the lengths and areas decreased gradually in both experimental groups. The area of the cornified layer and the length of the epithelial/connective tissue interface in the group treated for 2 months were significantly larger than those in animals treated for 2 weeks. These variables may be two of several indicators of prognostic significance in the assessment of dose-related premalignant epithelial hyperplasia.

Histomorphometric analysis of epithelial changes in chemically induced oral mucosal carcinogenesis in rats

Quantitative analysis of rat palatal mucosa after the carcinogen 4- nitroquinoline-1-oxide had been applied to the epithelium for varying periods of time showed that there was a significant increase in epithelial thickness, due largely to an increase in thickness of the basal compartment. This alteration was measurable before epithelial dysplasia could be recognised.

Quantitative exfoliative cytology of normal oral squames: an age, site and sex-related survey

This study describes the development of quantitative cytological techniques and their application to oral smears. Nuclear and cell size has been measured and matched with age, sex and site in an attempt to produce a baseline for comparison with identical measurements carried out on pathological smears. The results displayed a significant variation in nuclear and cytoplasmic area between different sites. Nuclear size varied significantly with advancing age; however, this was not the case for cytoplasmic area. There was no significant variation in either criterion between males and females.

An example of the use of quantitation in histological diagnosis by a comparison of normal human cheek mucosa and cheek mucosa affected by lichen planus

As an example of the use of quantitation in histological diagnosis the features of normal human cheek mucosa (NHCM) and non-ulcerative lichen planus of the cheek mucosa (LPCM) have been systematically studied and quantified in order to establish normal and pathological features which are constant. The technique enabled the quantitative verification of previously held concepts relating to NHCM and LPCM. A number of interesting features which have been given little attention in past literature were also noted. It is proposed that a reliable quantifiable range of characteristic histological features should be established for use in diagnosis where possible rather than relying on the subjective approach currently employed.

A differential diagnostic approach to the symptomatology of acute dental pain

Seventy-four patients with acute pulpitis, apical periodontitis, marginal periodontitis, or pulpoperiodontitis were examined. A series of symptoms and signs was registered. Diagnostic specificities and sensitivities were calculated, and thirteen variables were subjected to discriminant analysis and log-linear multiway contingency table analysis. Pulpoperiodonitis was found inseparable from pulpitis on the basis of the registered symptoms and signs. Several symptoms and signs previously believed to have differential diagnostic power were found insignificant. The following combination of symptoms and signs yielded a correct diagnosis in 82.1% of the cases: constant pain, tenderness to temperature changes, "the tooth feels extruded," impaired mouth opening, tenderness to palpation in apical area, and mobility.

Histometric study of leukoplakia, lichen planus and carcinoma in situ of oral mucosa

Leukoplakia, lichen planus and carcinoma in situ of human oral mucosa were analysed histometrically by light microscopy. Leukoplakia lesions showed a greater total nuclear density than lichen planus lesions. They had a similar basal nuclear density to carcinomas in situ. The total and basal nuclear areas were notably greater in carcinomas in situ, indicating the presence of larger nuclei in comparison to those of other lesions. We believe it to be possible to make a differential diagnosis based on numerical variables.

Oral leukoplakia and other white lesions of the oral mucosa related to dermatological disorders

"White lesions" of the oral mucosa often present problems of differential diagnosis, which are of primary importance when assessing precancerous changes in the mouth. The precancerous character of oral leukoplakia is well established, and the "high-risk" type: erosive-dysplastic leukoplakia of greater malignant potential, has been thoroughly investigated. Because of their possible association with oral carcinoma, some clinical types of oral lichen planus, namely, the atrophic erosive forms, indicate caution in their treatment and supervision. Epithelial dysplasia is often associated with candidiasis and discoid lupus erythematosus, but neither these, nor such other white lesions as white sponge naevus or morsicatio buccarum, are considered to be preneoplastic. All these white lesions may be clearly identified, differentiated, and circumscribed as clinico-pathological disease-entities, by clinical, histopathological and ultrastructural methods, thus facilitating early diagnosis, treatment and prevention of possible malignancy.

Epithelial cells kinetics. A review of methods of study and their application to oral mucosa in health and disease. Part B. Comparison of cell kinetics in normal and abnormal epithelia

In Part A, the techniques most commonly used to study epithelial cell kinetics and their suitability for use in man are reviewed. In Part B, the application of such methods to comparative studies of normal and abnormal oral epithelial of both man and experimental animals is examined. Claims regarding the possible prognostic value of LI's or MI's of biopsies of potentially or overtly malignant human oral lesions are also considered. Normal and abnormal kinetic data for other lining epithelia, e.g., skin, uterine cervix and gastrointestinal mucosa are assessed where they provide a better illustration of some of the problems arising in such comparative investigations. Finally, the present and likely future areas in which cell kinetic studies may provide a guide to expected tumour prognosis and optimum treatment are summarized.

Computer analysis of the surface ultrastructural features of porcine oral mucosa

The surface features of histologically definable regions were recorded from standardized random scanning-electron micrographs. Computer-based discriminant and cluster statistical analyses were used to determine whether these surface features reflect only degrees of keratinization or are specific characteristics of each mucosal site. It was possible to distinguish consistently between keratinized and non-keratinized mucosa but, as a means of individual tissue identification, the analysis offered no advantages over conventional histological examination.

Hamster tongue carcinogenesis II. Quantitative morphologic aspects of preneoplastic epithelium

Stereological techniques have been used to quantify some morphologic aspects of non-neoplastic and preneoplastic hyperplasia in hamster tongue. Scratching hamster ventral lingual mucosa and applying acetone thrice weekly resulted in moderate epithelial hyperplasia in biopsy material removed at 16 weeks. There was a significant increase in the number of progenitor cells per defined histologic field and a striking increase in the number of progenitor cells related to each unit of surface length. There was a small but significant increase in basement membrane length. In the experimental group in which the ventral lingual mucosa was scratched and painted with 0.5% DMBA in acetone there was pronounced epithelial hyperplasia with increases in the thickness of the progenitor, maturation and keratinized compartments. Progenitor cells showed hyperplasia and hypertrophy. The number of progenitor cells related to each unit of surface length was significantly greater than normal or control values. There was a significant increase in the basement membrane length per field, reflecting an increased folding and prominence of the rete ridges.

Variations in the nuclear-cytoplasmic ration during epithelial differentiation in experimental oral carcinogenesis

An increased nuclear-cytoplasmic ratio is one of the cytological features of epithelial atypia taken into account when the histopathologist subjectively assesses whether an epithelial lesion is likely to become malignant. The present work evaluates this ratio ultrastructurally in the DMBA-treated hamster cheek pouch model with a view to assessing whether alterations of this feature represent a valid indicator of malignant transformation. Following DMBA treatment, lesions obtained were assigned to three defined histopathological categories, namely epithelial hyperplasia, epithelial dysplasia and squamous cell carcinoma. Untreated pouches served as controls. Electron micrographs were obtained of basal, spinous and granular layer cells from each of these categories and the N/C ratio was evaluated using stereological point counting techniques. The results indicated that progressive decreases in the ratio occurred in all pathological stages during differentiation (i.e., between basal and granular cells). During carcinogenesis there was a tendency for the ratios to decrease in each cell layer but significant differences were not detected between normal and premalignant lesions.

Stereological analysis of histological parameters in experimental premalignant hamster cheek pouch epithelium

Hamster cheek pouch mucosa was treated with the carcinogen DMBA in order to provide samples of epithelium in the various pathological stages of carcinogenesis. Stereological techniques were applied to histological sections of normal and carcinogen-treated epithelium in order to quantify cytological and tissue parameters that may be related to the features of epithelial atypia. The results were compared with values previously obtained for benign epithelial hyperplasia induced by a solution of oil of turpentine. Of the parameters investigated, the nuclear-cytoplasmic ratio, nuclear numerical density and volume-to-interface area ratios were best able to distinguish between benign and premalignant epithelium. The ability to ascribe actual numerical values to histological features which are usually only subjectively evaluated may be a useful diagnostic aid.

Scanning electron microscopy of oral epithelial cells. Part II. Potentially malignant lesions (a computer-assisted study)

The technique described in Part I, has been extended to the examination of cells removed by scraping from 22 lesions of oral lichen planus and leukoplakia. It was concluded that the surface morphology of the cells from these lesions was intermediate between that of normal tissue and of malignant tissue. The observations have been quantified and subjected to computer analysis together with the data derived from the observations of normal and malignant tissue. This confirms the visual observation that a relationship exists between the modified surface characteristics of the cells from these lesions and their subjectively assessed histological appearances. A correlation has been found between the SEM appearance and an epithelial atypia index (EAI) derived according to the criteria of Smith and Pindborg (1969). In the case of lichen planus inflammatory changes appear to be associated with increased modification of surface characteristics. These changes are also reflected in an increased EAI. It is suggested that the present technique may be of value in the diagnosis and assessment of potentially malignant lesions.

The diagnostic significance of Russell bodies in endoscopic gastric biopsies

The incidence of cells containing so-called Russell bodies in 315 benign single gastric biopsies taken from stomachs with proven carcinoma, but outside the carcinomatous area and 786 biopsies taken from stomachs without carcinoma were compared. The Russell body containing cells were counted in a fixed area and on the basis of the counting each biopsy was classified in one of four groups: Russell body containing cells absent or present in a number of 1-5, 6-10 or more than 10 in the area. The results showed that endoscopic biopsy examinations containing one single benign biopsy with more than 5 Russell body containing cells in the carcinoma. If half or more than half of the biopsies in the examination contained 1-5 Russell body containing cells significant differences were also found. The sensitivity of such examinations was low but their predictive values (PVpos) varied from 46 per cent to 95 per cent, meaning that such examinations may be of importance for the diagnosis of gastric cancer.

The role of histopathology in diagnosis and prognosis of oral squamous cell carcinoma

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Further studies on lesions of the oral mucosa using computer-aided analyses of histological features

The histological feature of various "white lesions" of the oral mucosa have been subjected to computer-aided analyses, with the objectives of improving the accuracy of diagnosis, and the more reliable identification of the lesions most likely to progress to carcinoma.Previous reports on these studies have shown the potential usefulness of cluster and discriminant analyses, both for the classification of cases into their diagnostic groups, and for the identification of the tissue changes most useful in discriminating between one disease and another.The present report describes two extensions of this work. The first was the application of a scoring technique, based on discriminant analysis, to a new series of cases. In this series, the computer "correctly" identified 36 out of 41 that had been diagnosed as lichen planus by conventional methods. The second part of the study involved the calculation of the importance of each histological variable in defining the characteristics of groups of cases placed into different diagnostic groups or clusters by the computer. From these calculations, it was possible to depict the histological characteristics of each group in diagrammatic form.

The mitotic values for the epithelium in oral keratoses and lichen planus

In biopsies from the oral mucosa of 235 cases in which the diagnosis was lichen planus, keratosis or leukoplakia, mitotic values were calculated for the stratum basale (M.V. basal) and the stratum spinosum (M.V. spinous). The mean M.V. basal was significantly different from the mean M.V. spinous in the keratosis and leukoplakia groups, but not in the lichen planus group. Within the keratosis and leukoplakia groups, M.V. basal and M.V. spinous were significantly correlated. When each of the mean M.V.s was compared with the M.V.s for the other diagnostic groups, various significant differences were found. The M.V.s were examined in relation to the type of keratinization, the presence of acanthosis or atrophy, and the patient's age, but the M.V.s were not significantly related to these features.