Spectrum of Oral Cavity Lesions and its Clinico-Histopathological Correlation

Introduction: Oral cavity lesions comprise a wide spectrum of diseases varies from non-neoplastic to neoplastic. Clinical evaluation alone is insufficient for proper diagnosis in most of the cases. So, histopathological examination is gold standard method for diagnosis and management of patient accordingly. Objective: The present study was done to evaluate the histopathological spectrum of oral cavity lesions and compare them in relation to age, sex, site, clinical features, risk factors and clinical diagnoses. Methods: This prospective cross sectional study enrolled 127 cases of oral biopsies which were received at Department of Pathology, Tribhuvan University and Teaching Hospital, Kathmandu Nepal, from May 2018 to April 2019 for histopathological examination. Specimens were fixed in 10% formalin and subjected for tissue processing and Hematoxylin and Eosin stained sections. Data entry and analysis was done by using SPSS 24 version where frequency and percentile were calculated. Results: Total cases were 127 with slight female predilection and age group of 50-60 years (mean age of 44.24 years) were commonly affected. Tongue being most common site, frequently lesions presented as swelling. Most of the lesions were non neoplastic comprising 45% whereas malignant lesions comprised 23.6%. Smoking increased risk of malignancy by 2 fold. The most common benign lesions were squamous papilloma & fibroepithelial polyp whereas malignant lesion was squamous cell carcinoma. Sixty percent of clinical diagnoses didn’t show correlation. Conclusions: Oral cavity lesions have wide spectrum of distribution in age, sex, site and clinical presentation. Initially oral lesions may present with subtle symptoms which may cause underdiagnosis. Thus, histopathological diagnosis is a must to rule


INTRODUCTION
Oral cavity begins at the vermillion border of the lips and is delimited above by the hard palate, below by the floor of the mouth, laterally by the buccal mucosa (inner cheek) and posteriorly by the retromolar trigone and glossopalatine fold. A wide variety of lesions ranging from non-neoplastic to neoplastic involve the oral cavity. Tumor may originate from epithelial tissue, connective tissue, muscle tissue, nerve tissue and vessels. Oral cancer is one of the six most frequently occurring cancers and squamous cell carcinoma (SCC) is the common type. 1 Most people with oral and oropharyngeal cancers have history of tobacco use and the risk of developing these cancers is related to frequency and duration they smoked or chewed. 2 provide treatment accordingly. So, histopathological examination detects premalignant and malignant lesions at earlier stage.
Thus, main aim of this study is to find out nature of lesions, its predilection with age, sex, site, association with risk factors and clinico-histopathological correlation.

METHODS
This study was a hospital based cross sectional prospective study done for one year from 1 st May 2018 to 30 th April 2019. All the patient presenting to Department of Pathology, histopathology unit, Tribhuvan University Teaching Hospital, Kathmandu, Nepal for histopathological examination of oral cavity lesions were included in study. Inclusion criteria's were specimens which were adequate and representative of the lesion and resected surgical specimens like wide local excision, incisional biopsies, punch biopsy, wedge biopsies, surgical excision, hemi-glossectomy whereas exclusion criteria includes inadequately preserved specimens; neoplasm arising from nasopharynx or oropharynx; bone tumors of mandible, maxilla and odontogenic lesions.
Tissue biopsies received in 10% formalin in the Department of Pathology were subjected to gross examination and the size, appearance, external surface, cut surfaces were noted. Representative sections were taken, processed, embedded in paraffin block and sliced to obtain five micron thick sections. The slides were then stained with routine hematoxylin and eosin stain and other special stains wherever required. All sections were examined for the pathological lesions.
A structured questionnaire was used on all the study population and filled up. Information obtained was entered into master chart. Computer software "statistical package for social science" (SPSS) 24 was used for processing and analysis of the data.
Approval from the Institutional Review Board of Institute of Medicine (Ref No. 356), Tribhuvan University Teaching Hospital and Research Department was taken. All the individuals in the study were informed and explained about the study prior to enrollment. Written informed consent was obtained.
Malignant and premalignant lesions were more common in older age group ranging from 51 to 70 years whereas non neoplastic and benign lesions were frequently found in 31 to 40 years of age. Tongue showed more predilection for non-neoplastic lesions which comprised 26 cases (45.5%) followed by benign (14 cases, 25%) and malignant lesions (13 cases, 10.5%).
Lesions presented as swelling were mostly benign and non-neoplastic in nature which constituted 36 cases (46%) and 30 cases (39.5%) respectively ( Table 1). Most of malignant lesions presented as ulcer (18 cases, 53%) whereas non neoplastic and benign lesions presented as swelling. Fifteen cases (65%) of patients with malignant lesions had habit of smoking and 5 cases (18.5%) patients had habit of chewing gutka/paan.
The relative risk was calculated by using relative risk formula = Probability of getting disease by exposed to risk factor/probability of getting disease by nonexposed. There was strong association of risk factors with malignant lesions with relative risk of 2.2 with smoking, 2.3 with gutka/paan and alcohol each and 2 with tobacco. Most common non neoplastic lesion was keratosis with no dysplasia which accounted for 22 cases (38%), followed by mucocele which comprised 9 cases (16%). The most common benign lesions were squamous papilloma and fibroepithelial polyp (6 cases each, 20%), followed by pyogenic granuloma (5 cases, 16.6%) ( Table 2).
The most common premalignant lesion was low grade dysplasia which accounted for 4 cases (45%) followed by actinic cheilitis which comprised of 3 cases each (33%).
The most common malignant lesion was squamous cell carcinoma which comprised 28 cases (93.6%) showing nests and lobules of atypical squamous cells, keratin pearls on histopathological examination ( Figure 3) followed by adenoid cystic carcinoma comprised 2 cases (Figure 4). Out of the total 127 cases, 51 (40%) clinical diagnoses correlated with histopathological diagnoses. The youngest case was 2 months female diagnosed with mucocele and the oldest one was 86 years old female diagnosed as lobular capillary hemangioma. Increased number of lesions in older age group could be due to their long standing oral habits. The main site of occurance reported in this study was tongue (45%) followed by lip (24%) (Figure 2) which is similar to other studies in literature 5 , in contrast Wahi et al. 8 and Modi et al. 9 showed buccal mucosa as the commonest site.
In index study, 45 patients had habit of smoking, females (53%) being more than males which is highly discordant with Prashant et al. 10 done in Karnataka, India. Overall 33% of the smokers had malignancy in our study, which were evenly distributed in both sexes. The relative risk for smokers was 2.2. Case control study done over a period of 19 months in Pune, India showed significant risk of smoking on oral cancer with odds ratio of 4.1. 11 Muwonge et al. 12 found that tobacco chewing as the strongest risk factor associated with oral cancer. In the present study, common presentation of oral cavity lesions was swelling (80 cases, 63%) followed by ulcer (34 cases, 27%) (  24 Ahluwalia et al. 25 showed 82.7% and 89.9% of squamous cell carcinoma respectively. This infers the most common malignant lesion being squamous cell carcinoma which holds true for our study as well.
Regarding clinicopathological correlation, 60% of histopathological examinations did not correlate with clinical diagnosis. There have been varying discrepancy rates between histopathology and clinical diagnosis in various studies. Disparity in correlation between clinical and histopathological examination of oral lesions could be explained on the basis of inter-observer variation.

CONCLUSIONS
Oral cavity comprises wide spectrum of lesions varying from inflammatory to malignant. Although lesions show almost equal distribution in males and females, malignant lesions were more common in males. Tongue was most common affected site with frequent lesions were non neoplastic, clinically presented as swelling. However, malignant lesions presented as ulcer. Smoking increased risk of  malignant lesions by two fold. The most common benign lesions were squamous papilloma and fibroepithelial polyp whereas squamous cell carcinoma was the most common malignant lesions.
Sixty percent cases showed discrepancy between clinical and pathological diagnosis which show that biopsies are an integral part of evaluating lesions.
Therefore, correlation with clinical diagnoses, site of lesions and finally histopathological examination is required for proper evaluation and treatment of patients.