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Year : 2017  |  Volume : 9  |  Issue : 1  |  Page : 34-42

An inter-correlative study on clinico-pathological profile and different predisposing factors of oral leukoplakia among the ethnics of Darjeeling, India

1 Department of Pathology, North Bengal Medical College & Hospital, Darjeeling, India
2 Department of Oral Pathology, North Bengal Dental College & Hospital, Darjeeling, India

Date of Web Publication14-Jun-2017

Correspondence Address:
Krishnendu Mondal
c/o - Barendra Nath Mondal, Fularhat, Sonarpur, Kolkata 700150, West Bengal
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0975-8844.207942

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Context: Idiopathic leukoplakia is the most common potentially malignant disorder of oral cavity. Owing to the year-wide cold environment in Darjeeling, here the indigenous ethnic people practice a distinct addiction pattern that strongly predisposes them to oral leukoplakia. Aims: The purpose of the present study was to assess the clinico-pathological profile and various predisposing factors involved in oral leukoplakia, and to correlate its exfoliative cytological appearances with the histopathological diagnoses. Materials and Methods: A total of 53 patients were clinically diagnosed with oral leukoplakia during the study period. All information − clinical data pertaining to the patient and the patch, their personal history including addiction and diet, and the cyto-histopathological features of the lesion − was evaluated and methodically compared with each other using the statistical software, Statistical Package for the Social Sciences version 16.0. Results: The female-dominated cohort was chiefly affected with thin leukoplakia (67.9%) involving their buccal mucosa (66.1%). Smokeless tobacco (49.1%) was the most popular addiction. Alcoholism and smoking, increasing daily frequency of tobacco misuse, and verrucous and granular leukoplakias were significantly associated with dysplastic transformation (P < 0.05). Out of 16 (30.2%) dysplastic lesions, exfoliative cytology correctly diagnosed only six (11.3%) cases with a sensitivity of 37.5% only. Conclusion: Verrucous and granular variants are the most detrimental forms of oral leukoplakia. Dysplastic transformation frequently occurs in people addicted to smoking and alcoholism, and verrucous and granular leukoplakia. Lastly, exfoliative cytology poorly predicts the dysplastic evolution within a leukoplakic patch.

Keywords: Alcohol, areca nut, buccal mucosa, exfoliative cytology, oral leukoplakia, tobacco

How to cite this article:
Mondal K, Mandal R, Sarkar BC, Das V. An inter-correlative study on clinico-pathological profile and different predisposing factors of oral leukoplakia among the ethnics of Darjeeling, India. J Orofac Sci 2017;9:34-42

How to cite this URL:
Mondal K, Mandal R, Sarkar BC, Das V. An inter-correlative study on clinico-pathological profile and different predisposing factors of oral leukoplakia among the ethnics of Darjeeling, India. J Orofac Sci [serial online] 2017 [cited 2023 Feb 1];9:34-42. Available from:

  Introduction Top

Oropharyngeal cancer is the eighth most common cancer worldwide.[1],[2] But in India, being the third most prevalent cancer, it accounts for over 30% of all malignancies.[3] Idiopathic leukoplakia is the most common potentially malignant disorder (PMD) of oral mucosa. In India, its prevalence ranges from 0.2 to 8.2% according to different geographic regions,[4],[5],[6] and its precancerous transformation rate varies from 0.1 to 17.5%.[5],[7]

Literally, ‘leukoplakia’ means ‘white patch’. It is exclusively a clinical diagnosis. Ideally, following biopsy, the designation ‘leukoplakia’ should be replaced with the histopathological diagnosis. In other words, leukoplakia denotes a negative diagnosis, based on exclusion of other similar-appearing lesions such as lichen planus, chronic cheek-bite and frictional keratosis.[8] Rightfully so, the World Health Organization (WHO) defined it as ‘a clinical white patch that cannot be characterized clinically or pathologically as any other disease’.[9]

Many physical agents have been proposed in the aetiopathogenesis of leukoplakia including tobacco, alcohol, chronic friction due to ill-fitting denture or areca nut chewing, ultraviolet radiation and electrogalvanic reaction between restorative metals. The topmost prevalence has been noted among people practising mixed addictions, while tobacco smoking is by far the most accepted individual risk factor.[8],[10]

The utility of exfoliative cytology in oral PMDs was appreciated within a decade following its introduction in cervico-vaginal cytology.[11] Apart from being an early diagnostic tool for imminent malignancy, it may also aid in the formulation of further therapeutic strategies. However, conflicting outcomes have been recorded regarding the efficacy of various methodology as well as instruments employed in the cyto-preparation of the leukoplakic patches.[12],[13],[14],[15]

Darjeeling district in India has long been the habitat of indigenous ethnics such as Nepalese, Lepchas and Bhutias,[16] with relative paucity in the information about oral leukoplakia profile among them. In the background of such a scenario, the present study was aimed at evaluating the clinico-morphological profile, relative risk-association of various addictive and personal habits and correlative cyto-histopathological assessment in oral leukoplakia.

  Materials and Methods Top

This hospital-based prospective study was accomplished during July 2013 to June 2014, in joint association with the respective Departments of Pathology, and Oral Pathology from North Bengal Medical College & Hospital, and North Bengal Dental College & Hospital, both of which are the only tertiary care institutions in Darjeeling, India. During this entire period, a total of 169 cases suffering from idiopathic oral leukoplakia were examined. Out of them, a total of 53 patients belonged to the ethnic communities in Darjeeling, who were segregated for final research-assessment while they attended the oral pathology outpatient department and also satisfied the WHO definition[9] of oral leukoplakia. The prerequisite ethical approval for this study (Ethics Committee Pathology 2011–2014, Sl no. 45) was attained from the Institutional Ethics Committee of North Bengal Medical College and Hospital, Darjeeling, West Bengal, India, on 17th of December 2012. Patients with previously treated, recurrent or refractory lesions were excluded from the research tabulation.

On acquisition of proper consent from the patients, a comprehensive proforma was filled in for each personnel that detailed on their clinical profile and personal history including their addictive exercises. Exfoliative cytology was performed by scraping the patch firmly with conventional wooden tongue spatula humidified in normal saline. The materials were smeared over glass slides, fixed immediately and thereafter stained with the routine Papanicolaou stain. Appearance of pinpoint bleeding spots was accepted as the adequacy guideline for full-thickness cytological sampling. Biopsies were also taken in all cases using 4 mm punch under local anaesthesia. The tissues were routinely processed and stained with haematoxylin and eosin stain.

  Cytopathological and Histopathological Assessment Top

Cytological samples were categorized as hyperkeratosis without atypia, squamous epithelial hyperplasia without atypia, mild-to-moderate dysplasia, severe dysplasia/carcinoma in situ and invasive squamous cell carcinoma (SCC), abiding by the characterization illustrated in the book of ‘Koss’ Diagnostic Cytology and Its Histopathologic Bases’.[17] On histopathology, the lesions were classified according to WHO recommendations.[18] Apart from the three conventional grades of mild-to-severe dysplasia, infiltrating SCC and verrucous carcinoma, other benign diagnostic grades applied were hyperkeratosis, epithelial hyperplasia and lichenoid keratosis in absence of dysplasia.

  Statistical Analysis Top

Finally, all the results were compiled, scrutinized, tabulated and compared in all possible but relevant means using descriptive statistical software included in the Statistical Package for the Social Sciences version 16.0 software. Statistical significance was defined as P < 0.05.

  Results Top

The gender ratio among the observed 53 patients tilted in favour of females as 1.21:1. The age range was between 22 and 67 years, with a mean age of 40.7 years, and the majority (37.7%) of them belonged to the fourth decade of their life. Any apparent numeric discrepancies, between both sexes over the age groups, did not reckon for any statistical significance [P = 0.639; [Table 1].
Table 1: Age and sex distribution of different types of leukoplakia (N = 53)

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The buccal mucosa (66.1%) was the most frequently involved site, followed by the tongue (20.8%), the lips (7.5%), the gingiva (3.8%) and floor of the mouth (1.9%). In this respect, though there was an apparent feminine propensity towards labial and gingival involvement, the variation did not yield any significant statistical difference [P = 0.383; [Figure 1]]. Bilateralism was encountered in only 11 (20.8%) subjects, and the majority (eight cases, 15.1%) of them were males. This gender-wise discrimination concerning the laterality of leukoplakic patches turned statistically significant [P = 0.039; [Figure 2]].
Figure 1: Gender distribution of various sites involved with oral leukoplakia

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Figure 2: Gender distribution of the leukoplakic patches according to its laterality

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Thin leukoplakia, the most common variant, accounted for 67.9% of all cases. Other subtypes included thick homogeneous (17%), speckled (9.4%), granular (3.8%) and verrucous (1.9%) leukoplakia [Figure 3]. The prevalence of thin leukoplakia was highest among the youngsters, while the other variants prevailed through and beyond the fifth decade of their life attaining prominent statistical difference [P = 0.039; [Table 1]. However, gender-wise, such a differential occurrence of leukoplakia subtypes did not prove any statistical importance [P = 0.368; [Table 1]. None from the observed group manifested proliferative verrucous leukoplakia.
Figure 3: Clinical subtypes of oral leukoplakia: thin leukoplakia involving the buccal mucosa (a) and the tongue (b); thick homogeneous leukoplakia (c); speckled leukoplakia (d); granular (circle) leukoplakia (e); verrucous (arrow) leukoplakia (f)

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Causal effects of multiple addictions as well as personal factors were also evaluated in this context. From the statistical point of comparison, males were overwhelmingly more addicted to alcoholism and tobacco smoking compared to their female counterparts, and on the contrary, chewing of tobacco products (smokeless tobacco) and areca nut was significantly more popular among females. However, spicy diet consumption or artificial denture did not imply any significant statistical impact on the causation of oral leukoplakia [Table 2].
Table 2: Gender-wise distribution of various compounding factors in oral leukoplakia (N = 53)

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Altogether, eight (15.1%) lesions expressed cytological evidences of cellular atypia, two (3.8%) of which turned out to be non-dysplastic on histopathology. On the other hand, 10 (18.9%) cytologically bland lesions exhibited varying degrees of dysplasia on biopsy specimens. Overall, on statistical basis exfoliative cytology was proved to be a poor tool in depicting the actual pathology underlying oral leukoplakia (κ value: 0.36). At the same time, it was also evident that the non-dysplastic lesions were more commonly associated with the thin leukoplakia, just like reciprocally, the dysplastic pathology was more prominent in speckled, granular or verrucous leukoplakias [P = 0.002; [Table 3]. [Figure 4] and [Figure 5] illustrate the principal cytological and histopathological findings of the present study.
Table 3: Comparative evaluation of clinical, cytopathological and histopathological diagnoses (N = 53)

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Figure 4: Exfoliative cytology of oral leukoplakia (Papanicolaou stain): hyperkeratosis without atypia (40×, a); squamous epithelial hyperplasia without atypia (100×, b); mild-to-moderate dysplasia (100×, c); severe dysplasia (400×, d); squamous cell carcinoma (100×, e and 400×, f)

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Figure 5: Histopathology of oral leukoplakia (haematoxylin and eosin stain): hyperkeratosis without dysplasia (40×, a); epithelial hyperplasia without dysplasia (100×, b); lichenoid keratosis without dysplasia (100×, c); mild dysplasia (400×, d); moderate dysplasia (100×, e); severe dysplasia/squamous cell carcinoma in situ (100×, f); squamous cell carcinoma (40×, g); verrucous carcinoma (40×, h)

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Tobacco smoking and alcoholism were substantiated as significant risk factors for the development of dysplastic/malignant changes within a pre-existing leukoplakia [Table 2]. In this regard though tobacco chewing itself did not pose any significant association with these dysplastic patches, but alongside smoking, its increasing daily consumption improvised a significant risk-association with the leukoplakic lesions featuring dysplastic/malignant morphological changes [P = 0.016; [Table 4].
Table 4: Association of dysplastic/malignant changes with the frequency of tobacco smoking and/or chewing (N = 40)

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  Discussion Top

Darjeeling district, in the state of West Bengal in India, is thickly populated with tribal ethnics such as Nepalese, Lepchas, Bhutias and many others, particularly in its Himalayan hills and foothills.[16] Being part of a year-wide wintry environment, these people cherish their belief in potential calorific effects from tobacco and areca nut chewing in addition to other health benefits, mounting up immense popularity of these addictions.[19] A significant population of Indian women, compared to the men, prefer to chew areca nut as the single exclusive addictive measure.[20] In the United States, 20.6% adults are smokers, but only 4.4% males and 0.7% females are addicted to smokeless tobacco products. Similar pattern of tobacco addiction profile is also evidenced from the European nations.[21] But contradictorily, the recent Global Adult Tobacco Survey in 2010 reported that 35% of the Indian adults are addicted to tobacco products, of whom 21% are chewers, 9% are smokers and the remaining 5% consume both supplements.[22] The smokeless tobacco, in the shape of local remedies such as ‘paan’ (betel quid) or ‘guthka’ or ‘khainni’, is equally popular among both sexes of the Indian population. On the other aspect, the relative risk for developing oral PMD as well as oral cancer is much higher in females with tobacco chewing habits than their male counterparts.[23],[24] For this reason, globally leukoplakia is though more prevalent among males; still, in Indian scenario, its feminine dominance is as good as that of males.[25],[26],[27] In the same way, most of the female patients from the present study were chewers of areca nut and smokeless tobacco products. The higher relative risk for female chewers to progress into oral PMDs actually explains the near-equivalent representativeness of both the genders within the currently studied cohort.

Alcoholism and tobacco smoking too have long been proposed to play an instrumental role in the development of oral leukoplakia and subsequent oropharyngeal cancer.[28],[29],[30] In this context, Uplap et al.[31] derived an association between cessation of tobacco consumption and regression of pre-existing potentially malignant patches, implying a reduced risk for oral cancer. In the present study, all the four above-mentioned addictive measures were significantly associated with origination of leukoplakia. At the same time, smoking and alcoholism expressed a statistically relevant causal influence in their dysplastic transformation as well. Further observation revealed that the prevalence of dysplastic lesions significantly upgraded with the increasing daily usage of tobacco products. In a retrospective research work spanning three years, Garg et al.[32] also deduced an identical formulation between the dosage of tobacco supplementary and oral PMDs.

Thin and thick homogeneous leukoplakias were the most common subtypes encountered in present study, similar to the experience by Mishra et al.[25] though the rarer variants differed from theirs. The buccal mucosa carries highest propensity towards leukoplakic involvement. Exposure of this region of oral mucosa to higher amount of toxic metabolites, derived from tobacco, suspended in saliva is possibly responsible for its pathogenesis.[33] The topography of the buccal mucosal involvement also differs with the modality of tobacco consumption: such as the leukoplakic patch commonly affects the posterior part of the buccal mucosa in patients using smokeless tobacco, but the smokers are rather prone to be affected with a buccal patch that is situated more anteriorly.[34] However, the lesser common sites of oral leukoplakia varied through the literatures. The lips and the palate were the least frequent sites to get involved in the study conducted by Mishra et al.[25]; whereas that observed by Kumar et al.[35] were the tongue and the palate, and in the present study, those were the gingiva followed by floor of the mouth.

Oral idiopathic leukoplakia is predominantly unilateral. This feature is sometimes useful in differentiating it from oral hairy leukoplakia, lichen planus, etc., which are commonly bilateral.[8] Eleven (20.8%) subjects from the presently observed group manifested bilateral patches, eight of whom were males. Simultaneously, a gender-related statistically significant difference was observed regarding the occurrence of bilateral leukoplakias. But due to the paucity of any supporting literature on this fact, more data need to be accumulated before imposing a definite opinion, and since then, the present finding largely remains just an incidental observation.

In a study with leukoplakia among reverse smokers, Mehta et al.[12] examined 13.5% dysplastic lesions on biopsy. Recently, Gopinath et al.[36] histologically evaluated 546 leukoplakic patches. They isolated mild dysplasia, moderate dysplasia, severe dysplasia, SCC and verrucous carcinoma in 30%, 19.9%, 12.4%, 9.9% and 2% cases, respectively. Relatively smaller data series isolated much higher proportion of atypical lesions.[37] But contradictorily, on the largest follow-up study so far from India, Silverman et al.[38] recorded dysplastic transformation in only 0.13% lesions. Amidst such an antagonistic context, the present study evaluated total 53 lesions of oral leukoplakia, of which 16 lesions (30.2%) featured varying grades of dysplastic changes, and almost half of these (13.2%) were mildly dysplastic.

The premalignant potential of different leukoplakia variants has been listed in the following order: proliferative verrucous > speckled > verrucous > granular > thick homogeneous > thin,[25] whereas the same sequence in the present study was observed as verrucous and granular > speckled > thick homogeneous > thin. By fair means, such an order of dysplastic potentiality indicates that verrucous, speckled and granular subtypes are the most virulent, and the thin subtype is the most indolent form of oral leukoplakia. More significantly so, in the present study, these afore-mentioned harmful kinds of leukoplakias developed more susceptibly in patients who were beyond fourth decade of their life. Mehta et al.[12] studied 342 palatal leukoplakias and encountered eight cytologically atypical cases, two of which were diagnosed histologically as non-dysplastic. Among their cytologically benign-appearing lesions, 40 cases showed histopathological evidences of dysplasia. Similarly, Mishra et al.[25] diagnosed 290 cases as dysplastic and 21 cases straightaway as SCC on cytology. Out of those dysplastic lesions, 40 patches were proved to be benign on histopathology. Such a hapless performance of exfoliative cytology in determining the exact pathology underlying a leukoplakic patch again disappointed Olekar and his associates in 2012.[39] This kind of merely inefficient cytological yield is mostly attributable to the highly keratinizing nature of the lesion.[12] On the contrary, in an identical study on the Sri Lankan island, Ramaesh et al.[40] achieved a sensitivity of 89%, specificity of 89.7%, positive predictive value of 80% and negative predictive value of 94.4% using a standard wooden spatula for obtaining the exfoliated samples. Their successful findings were reciprocated almost in ditto by Navone et al.[37] and Kumar et al.[35] in the following years. During the discussed study, conventional wooden spatula was utilized for procuring exfoliative materials. This procedure acquired a poor sensitivity of only 37.5% in recognizing the dysplastic patches. Moreover, piling up to the misery, a poor agreement between exfoliative cytology and biopsy in diagnosing oral leukoplakia (κ value of 0.36) was also substantiated from the current research data.

  Conclusion Top

Finally, from the discussed study, it is concluded that idiopathic oral leukoplakia generally presents as a buccal white patch in people from their 30s. The lesions are usually unilateral. Thin leukoplakia is its most common variant and is least prone to dysplastic transformation as well, whereas verrucous leukoplakia is the less common variant, and alongside the granular subtypes, it most frequently undergoes dysplastic transformation. Smoking and alcoholism are significant risk factors for giving rise to a leukoplakic patch in males, and in case of females that much risk association is contributed by areca nut and chewable tobacco supplements. But, dysplastic lesions are significantly associated with tobacco smoking, alcoholism and the increasing frequency of daily tobacco consumption. Lastly and most importantly, oral exfoliative cytology is a poor diagnostic tool for predicting dysplasia in an oral leukoplakia, with a poor strength of agreement with the biopsy interpretation.


We acknowledge Professor MGM and Professor AG for their support and guidance.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]

  [Table 1], [Table 2], [Table 3], [Table 4]

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