Abstract
Objectives: To determine the frequency and spectrum of oral and maxillofacial lesions biopsied in a hospital population in the northern region of Portugal. Methods: We conducted descriptive analyses of pathology reports from biopsies of oral and maxillofacial lesions performed between 1990 and 2006, in Oporto Hospital Center. Information on gender and age of patient, location of the lesions and the histopathological diagnosis were analysed. Results: The analyses revealed that 1,520 (47.7%) patients were male and 1,666 (52.3%) were female. They had a mean age ± standard deviation of 47.8 ± 18.6 years. The site most frequently biopsied was the labial mucosa (17.5%). A non-neoplastic diagnosis was established in 2,162 (63.3%) cases, potentially malignant disorders in 163 (5.1%) and neoplasms in 886 (27.6%) (403 benign and 483 malignant). The most commonly reported diagnosis was fibroepithelial polyp (n = 186; 15.9%), followed by squamous cell carcinoma (SCC) (n = 158; 13.6%). SCC was the lesion most commonly found in male patients (n = 279; 18.4%) whilst fibroepithelial polyp was the lesion most commonly found in female patients (n = 268; 16.1%). The most common lesion in patients 0–17 years of age was a follicular cyst (n = 25; 12.8%), whereas in patients 18–64 years of age it was a fibroepithelial polyp (n = 299; 13%). SCC was the most common type of lesion found in patients ≥ 65 years of age (n = 160; 24.6%). Conclusion: This large sample provides useful information about the incidence and distribution of oral biopsies over a period of 16 years, allowing valuable comparison with other countries. Non-neoplastic lesions were the types of lesion most commonly reported, with fibroepithelial polyp being most frequent. SCC was the second most common diagnosis.
Key words: Histopathological analysis, oral biopsies, oral cavity, oral pathology, Portugal
Introduction
A wide range or lesions can develop in the oral cavity, with diverse origins and heterogeneous characteristics, including both benign and malignant lesions. Performing a biopsy is one of most important investigations in oral medicine. A biopsy not only shows the morphological characterisation of the tissue but also is the gold standard for obtaining a definitive diagnosis for many lesions, especially malignant diseases1. Oral health professionals, including general dentists, are very familiar with dental and periodontal lesions. However, the diagnosis of some lesions and diseases of the oral soft tissues can be challenging2. In view of this, the literature on the frequency and prevalence of oral and maxillofacial lesions not only increases awareness of disease patterns within populations, but highlights the lesions that oral health professionals are most likely to encounter in their daily practice.
Worldwide there have been few histological-based studies of oral and maxillofacial lesions that include a comprehensive spectrum both of oral lesions and patients of all ages3., 4., 5., 6., 7.. Most of the published reports were designed to analyse only a specific lesion or disease, and were limited to a certain age group or were based on screenings or clinical surveys, without histological diagnostic confirmation8., 9., 10., 11., 12., 13., 14., 15., 16., 17., 18..
The aim of this study was to determine the spectrum and the frequency of biopsied oral and maxillofacial lesions, in a North Portugal hospital population, comprising patients of all ages and genders, and then to compare the results with other studies reported worldwide.
Material and Methods
We performed a retrospective, 16-year (1990–2006) descriptive analysis of oral and maxillofacial biopsies, at the Pathology Department of the Hospital de Santo António (HSA) Oporto Hospitalar Center in Portugal. Patients from the Oporto community were referred by their general practitioner to this centrally based city hospital. The study was reviewed and approved by the Institutional Review Board of the Hospital de Santo António (HSA) Oporto Hospitalar Center [Investigation, Formation and Teaching Department (DEFI); 024/CES/03]. The study was performed in full accordance with the World Medical Association Declaration of Helsinki. Data regarding histopathological diagnosis and respective clinical information were retrieved from patient hospital records and transferred into a Microsoft® Excel database. The data were anonymised before analysis. In the analysis, information on gender, age, site of the lesion, clinical diagnosis and the histopathological diagnosis were included. Exclusion criteria were: biopsies showing normal tissue; repeated biopsies of lesions already diagnosed (e.g. the excisional removal of a lesion that was previously diagnosed with an incisional biopsy); and cases with unclear or missing data, or with an inconclusive diagnosis.
The lesions were classified using a system recommended by the International Classification of Diseases, Dentistry and Stomatology (ICD-DA), and by the World Health Organization Classification of Tumours (2005). For analysis, we decided to divide the diagnoses into three groups: non-neoplastic lesions; oral potentially malignant disorders (OPMD); and neoplastic lesions. These were further subdivided into nine major subcategories: inflammatory lesions; infective lesions; cystic lesions; reactive lesions; potentially malignant disorders; autoimmune or metabolic diseases; hamartomatous lesions or congenital alterations; benign neoplasms; and malignant neoplasms. Patients between 0 and 17 years of age were considered as young patients, between 18 and 64 years of age were classified as adult patients and 65 years of age and over were classified as elderly patients19., 20..
Statistical analysis was carried out using IBM SPSS Statistics version 22.0 software (IBM Corp., Armonk, NY, USA). The results are presented as absolute numbers and relative frequencies. Possible associations between pathological groups (non-neoplastic, OPMD and neoplastic groups) and categorical or continuous variables were evaluated using the chi-square test or analysis of variance (ANOVA), respectively. P < 0.05 was considered significant.
Results
From the original data set of 3,737 cases, we excluded 136 as they revealed a histopathological diagnosis of normal tissue (without cellular or tissue alterations). A further 389 cases were excluded for the following reasons: they were biopsies repeated for the same lesion; had missing data; or had an unclear diagnosis. Therefore, a final sample of 3,212 oral biopsies was included: 1,666 (52.3%) were from female patients and 1,520 (47.7%) were from male patients (female: male ratio of 1.10). In 26 patients the information on gender was absent. Within the sample, the patient's age ranged from 3 to 100 years, with a mean age ± standard deviation of 47.8 ± 18.6 years and the sixth decade being the most common (n = 628; 20%). There were 196 (6.2%) cases in the young age group, 2,300 (73.1%) in adults and 651 (20.7%) in the elderly group.
The oral site most frequently affected was the labial mucosa (n = 561), followed by the buccal mucosa (n = 550), tongue (n = 519), gingiva (n = 349), major salivary glands (n = 300), palate (n = 182), floor of the mouth (n = 75), maxilla (n = 357), mandible (n = 287) and mouth not otherwise specified (NOS) (n = 32).
When classified within pathological diagnostic groups, 2,162 (63.3%) lesions corresponded to non-neoplastic diagnoses, 163 (5.1%) were OPMD and 886 (27.6%) were neoplasms (Table 1). The non-neoplastic biopsies were more likely to be from female patients than from male patients, and this was in contrast to potentially malignant disorders and neoplasms (P < 0.001), which were more commonly from male patients. The mean age of patients with non-neoplastic lesions was lower than those observed in patients with neoplasms or OPMD (P < 0.001). The buccal mucosa was the site most affected with non-neoplastic lesions and OPMD, while the tongue was the site most affected with neoplasms (P < 0.001).
Table 1.
Number of lesions in diagnostic groups distributed according to gender, age and predominant location
| Diagnostic group | n | % | Gender* | P† | Age* | P‡ | Predominant site (%) | P† | |
|---|---|---|---|---|---|---|---|---|---|
| Female | Male | (mean ± SD) | |||||||
| Non-neoplastic | 2,162 | 63.3 | 1,239 | 909 | <0.001 | 45.06 ± 18.34 | <0.001 | BM (17.0) | <0.001 |
| OPMD | 163 | 5.1 | 73 | 90 | 56.14 ± 14.90 | BM (45.4) | |||
| Neoplasms | 886 | 27.6 | 354 | 521 | 52.80 ± 18.20 | TNG (23.8) | |||
| Total | 3,212 | 100 | 1,666 | 1,520 | 47.80 ± 18.60 | LAM (17.5) | |||
BM, buccal mucosa; LAM, labial mucosa; OPMD, oral potentially malignant disorders; SD, standard deviation; TNG, tongue.
In some patients gender is unknown.
P values for the differences were calculated using the chi-square test.
P values for the differences were calculated using analysis of variance (ANOVA).
Non-neoplastic group
The most common subcategory within non-neoplastic diagnoses was reactive lesions (n = 679), followed by cystic lesions (n = 647), inflammatory lesions (n = 636), autoimmune or metabolic conditions (n = 89), hamartomatous or congenital lesions (n = 67) and infective lesions (n = 45). The most prevalent reactive lesion was the fibroepithelial polyp (n = 385). This was more commonly observed in female patients (n = 268); patients affected had a mean age of 48.98 ± 16.20 years, and the buccal mucosa was that most frequently affected (47%). Regarding cysts and odontogenic tumours, the inflammatory odontogenic cyst was the lesion most commonly found (n = 264). The mean age of patients affected was 38.37 ± 15.90 years, with male patients being more frequently affected (n = 152), and this lesion presented mainly in the maxilla (69.7%). Other non-neoplastic lesions and their distribution, according to gender, age and site, are presented in Table 2 and Tables S1–S6.
Table 2.
Number of non-neoplastic diagnoses in each diagnostic category (including the five most prevalent lesions in each category), distributed according to gender, age and predominant site
| Diagnostic category | n | % | Gender* | Age* | Predominant site (%) | |
|---|---|---|---|---|---|---|
| Female | Male | (mean ± SD) | ||||
| Inflammatory lesions | 636 | 29.4 | 363 | 265 | 48.37 ± 18.39 | GEN (23.1) |
| Non-specific ulcer | 96 | 4.4 | 53 | 42 | 51.60 ± 18.60 | TNG (40.6) |
| Chronic sialadenitis | 91 | 4.2 | 49 | 40 | 46.68 ± 14.20 | MSG (85.7) |
| Pyogenic/pregnancy granuloma | 89 | 4.1 | 57 | 31 | 46.61 ± 20.10 | GEN (36.0) |
| Chronic inflammation | 83 | 3.8 | 48 | 34 | 51.38 ± 17.50 | LAM (30.1) |
| Peripheral giant-cell granuloma | 49 | 2.3 | 27 | 22 | 45.14 ± 23.80 | GEN (71.4) |
| Infective lesions | 45 | 2.0 | 31 | 14 | 47.59 ± 19.48 | MAN (20.0) |
| Actinomycosis | 11 | 0.5 | 9 | 2 | 57.00 ± 18.60 | GEN (66.7) |
| Warts | 9 | 0.4 | 6 | 3 | 38.89 ± 20.60 | LAM (66.7) |
| Tuberculosis | 7 | 0.3 | 6 | 1 | 53.57 ± 24.00 | PAL (100.0) |
| Abscess/Fistula | 5 | 0.2 | 3 | 2 | 36.20 ± 11.90 | MNOS (40.0)+ MAX (40.0) |
| Syphilis ulcer | 3 | 0.1 | 0 | 3 | 55.00 ± 4.60 | TNG (66.7) |
| Cystic lesions | 647 | 29.9 | 273 | 372 | 35.90 ± 17.40 | MAX(47.6) |
| Inflammatory odontogenic cyst | 264 | 12.2 | 112 | 152 | 38.37 ± 15.90 | MAX (69.7) |
| Follicular cyst | 97 | 4.4 | 40 | 57 | 32.90 ± 17.50 | MAN (50.5) |
| Mucocele/retention cyst | 91 | 4.2 | 31 | 59 | 33.56 ± 18.70 | LAM (79.1) |
| Keratocyst | 46 | 2.1 | 29 | 17 | 36.52 ± 19.20 | MAN (87.0) |
| Ameloblastoma | 16 | 0.7 | 4 | 12 | 40.56 ± 17.90 | MAN (81.3) |
| Reactive lesions | 679 | 31.4 | 457 | 218 | 50.00 ± 16.10 | BM (37.4) |
| Fibroepithelial polyp | 385 | 17.8 | 268 | 114 | 48.98 ± 16.20 | BM (47.0) |
| Epulis fissuratum | 71 | 3.3 | 61 | 10 | 55.24 ± 11.40 | GEN (52.1) |
| Fibroepithelial epulis | 66 | 3.0 | 44 | 22 | 47.91 ± 15.70 | GEN (100.0) |
| Keratosis | 57 | 2.6 | 27 | 30 | 52.95 ± 14.80 | TNG (47.4) |
| Epithelial hyperplasia | 51 | 2.3 | 28 | 22 | 54.48 ± 17.60 | TNG (31.4) |
| Autoimmune or metabolic lesions | 89 | 4.1 | 72 | 17 | 49.97 ± 15.49 | LAM (62.9) |
| Sjögren's syndrome | 48 | 2.2 | 47 | 1 | 50.83 ± 12.80 | LAM (93.8) |
| Pemphigus | 13 | 0.6 | 8 | 5 | 53.54 ± 13.60 | BM (84.6) |
| Amyloidosis/amyloid substance | 7 | 0.3 | 2 | 5 | 61.86 ± 16.80 | LAM (57.1) |
| Pemphigoid | 4 | 0.2 | 4 | 0 | 63.50 ± 19.80 | GEN (50.0) |
| Erythema multiform | 4 | 0.2 | 3 | 1 | 35.50 ± 18.10 | LAM (50.0) |
| Congenital or development disorders | 67 | 3.0 | 43 | 23 | 43.30 ± 18.60 | LAM (41.8) |
| Vascular anomalies | 37 | 1.7 | 22 | 14 | 49.90 ± 17.90 | LAM (48.6) |
| Exostosis | 8 | 0.4 | 6 | 2 | 46.38 ± 15.90 | MAN (62.5) |
| Melanocytic nevus | 6 | 0.3 | 2 | 4 | 32.17 ± 16.90 | LAM (100.0) |
| Lentigo | 4 | 0.2 | 4 | 0 | 30.00 ± 13.30 | LAM (75.0) |
| White spongy nevus | 3 | 0.1 | 1 | 2 | 33.00 ± 26.10 | BM (66.7) |
| Total | 2,162 | 100 | 1,239 | 909 | 45.06 ± 18.34 | BM (17.0) |
BM, buccal mucosa; GEN, gingiva; LAM, labial mucosa; MAN, mandible; MAX, maxilla; MNOS, mouth non-otherwise specified); MSG, major salivary glands; PAL, palate; SD, standard deviation; TNG, tongue.
In some patients gender is unknown.
Oral potentially malignant disorders
Leukoplakia was the most common potentially malignant oral disorder (n = 76), being found in subjects with a mean age of 57.53 ± 15.66 years and predominantly in male patients (n = 48). The most affected location was the buccal mucosa (36.8%). Other potentially malignant oral disorders and their distribution, according to gender, mean age and predominant location, are presented in Table 3.
Table 3.
Number of potentially malignant disorders distributed according to gender, age and predominant site
| Diagnostic category | n | % | Gender | Age | ||
|---|---|---|---|---|---|---|
| Female | Male | (mean ± SD) | Predominant site (%) | |||
| Leukoplakia* | 76 | 46.60 | 28 | 48 | 57.53 ± 15.66 | BM (36.8) |
| Lichen planus | 61 | 37.40 | 32 | 29 | 50.9 ± 14.42 | BM (70.5) |
| Actinic cheilitis | 18 | 11.04 | 9 | 9 | 64.94 ± 8.20 | LAM (100) |
| Epithelial dysplasia† | 7 | 4.30 | 3 | 4 | 62.29 ± 10.83 | BM (42.9) |
| Erythroplasia | 1 | 0.61 | 1 | 0 | 70.00 | FOM (100) |
| Total | 163 | 100 | 73 | 90 | 56.14 ± 14.9 | BM (45.4) |
BM, buccal mucosal; FOM, floor of the mouth; LAM, labial mucosa; SD, standard deviation.
Including cases with hyperkeratosis or epithelial hyperplasia (without dysplasia) with a clinical diagnosis of leukoplakia.
Including leukoplakias with dysplasia.
Neoplasms
Of the 886 neoplasms, 403 were benign and 483 were malignant (Tables S7, S8). The benign pleomorphic adenoma was the most frequent benign neoplasm, affecting mainly the major salivary glands (MSG) (75%) and especially the parotid gland (n = 69; 83.1% of MSG), with more cases noted in female patients (n = 69) with a mean age of 43.38 ± 17.7 years. If we exclude the major salivary glands, the most frequent benign neoplasm was the epithelial cell papilloma (n = 96; 34% of all oral cavity locations). The most common malignant neoplasm was squamous cell carcinoma (n = 373). This tumour was more common in male patients (n = 279), the mean age of patients was 61.55 ± 13.5 years and it affected predominantly the tongue (30.8%). Regarding salivary gland malignancies, mucoepidermoid carcinoma (n = 13) was the most common salivary gland malignancy: it mostly affected major salivary glands (38.5%), especially the parotid gland (n = 5; 100% of MSG). This was followed by adenoid cystic carcinoma (n = 10), which was located most often in the floor of the mouth (30%) and MSG (30%), especially in the submandibular gland (n = 2; 66.6%). Table 4 provides the neoplastic lesions distributed according to gender, mean age and the predominant location.
Table 4.
Number of neoplastic diagnoses in each diagnostic category (including the five most prevalent in each category and tissue origin), distributed according to gender, age and predominant site
| Diagnostic category | n | % | Gender* | Age* | ||
|---|---|---|---|---|---|---|
| Female | Male | (mean ± SD) | Predominant site (%) | |||
| Benign neoplasms | 403 | 12.5 | 225 | 173 | 44.80 ± 18.2 | MSG (30.8) |
| Epithelial origin | ||||||
| Pleomorphic adenoma | 112 | 12.6 | 69 | 43 | 43.38 ± 17.7 | MSG (75) |
| Squamous cell papilloma | 96 | 10.8 | 57 | 38 | 43.46 ± 17.9 | TNG (39.6) |
| Warthin's tumour | 25 | 2.8 | 2 | 23 | 54.50 ± 12.8 | MSG (96) |
| Basal-cell adenoma | 7 | 0.8 | 5 | 2 | 56.43 ± 11.3 | MSG (71.4) |
| Adenoma NOS | 6 | 0.7 | 6 | 0 | 57.30 ± 8.8 | BM+PAL (66) |
| Mesenchymal origin or others | ||||||
| Haemangioma | 55 | 6.2 | 34 | 21 | 49.31 ± 17.0 | LAM (52.7) |
| Lipoma | 23 | 2.6 | 6 | 15 | 54.81 ± 16.5 | BM(26.1) |
| Fibroma | 22 | 2.5 | 14 | 7 | 43.95 ± 16.7 | BM (50) |
| Lymphangioma | 12 | 1.4 | 7 | 5 | 41.25 ± 19.6 | TNG (58.3) |
| Granular cell tumour | 6 | 0.7 | 4 | 2 | 34.60 ± 7.0 | TNG (100) |
| Malignant neoplasms | 483 | 15.0 | 129 | 348 | 59.70 ± 15.2 | TNG (26.3) |
| Epithelial origin | ||||||
| Squamous cell carcinoma | 373 | 42.1 | 91 | 279 | 61.55 ± 13.5 | TNG (30.8) |
| Mucoepidermoid carcinoma | 13 | 2.7 | 7 | 6 | 47.25 ± 17.8 | MSG (38.5) |
| Adenoid cystic carcinoma | 10 | 1.1 | 3 | 6 | 53.22 ± 13.6 | FOM+MSG (60) |
| Carcinoma in situ | 6 | 0.7 | 1 | 5 | 62.83 ± 16.8 | LAM (50) |
| Verrucous carcinoma | 5 | 0.6 | 2 | 3 | 70.60 ± 9.4 | GEN (40) |
| Undifferentiated carcinoma | 5 | 0.6 | 1 | 4 | 52.00 ± 20.9 | GEN (40) |
| Mesenchymal origin and others | ||||||
| Lymphoma | 25 | 2.8 | 13 | 12 | 51.12 ± 21.7 | MSG (24) |
| Kaposi's sarcoma | 9 | 1.0 | 0 | 9 | 36.78 ± 5.2 | PAL (55.6) |
| Metastasis | 8 | 0.9 | 2 | 6 | 67.38 ± 12.3 | LAM+TNG+MSG (75) |
| Sarcoma NOS | 2 | 0.2 | 1 | 1 | 22.00 | GEN (100) |
| Plasmocytoma | 2 | 0.2 | 1 | 1 | 42.50 ± 16.3 | GEN+MAN (100) |
| Total | 886 | 100 | 354 | 521 | 52.80 ± 18.2 | TNG (23.8) |
BM, buccal mucosa; FOM, floor of the mouth; GEN, gingiva; LAM, labial mucosa; MAN, mandible; MSG, major salivary glands; NOS, non-otherwise specified; PAL, palate; SD, standard deviation; TNG, tongue.
In some patients gender is unknown.
The top 10 diagnoses distributed by gender and age
We investigated the 10 most common diagnoses of the entire sample population (Figure 1). Fibroepithelial polyp (n = 385) was the most common lesion, followed by squamous cell carcinoma (n = 373). By analysing the distribution of the lesions according to gender, we observed that the fibroepithelial polyp (n = 268) was the lesion most frequently found in female patients, whereas SCC was the lesion most commonly found in male patients (n = 279) (Figure 2). When we analysed the most common diagnoses stratified according to age group, follicular cyst (n = 25) was the predominant lesion in young patients (0–17 years of age), fibroepithelial polyp was the most common lesion in adult patients (18–64 years of age) (n = 299) and SCC (n = 160) was the most prevalent lesion in elderly patients (≥ 65 years of age) (Figure 3).
Figure 1.
The 10 most common histological diagnoses (1990–2006).
Figure 2.
The 10 most common histological diagnoses distributed according to gender (1990–2006). (a) Male subjects. (b) Female subjects.
Figure 3.
The 10 most common histological diagnoses, distributed according to age group (1990–2006). (a) Young patients (0–17 years of age). (b) Adult patients (18–64 years of age). (c) Elderly patients (65+ years).
Discussion
Information on the frequency of oral and maxillofacial lesions is an important aspect of oral health practice and provides epidemiological information on the distribution of such lesions within populations. From this descriptive retrospective analysis (1990–2006), 3,212 oral biopsies were included, representing a 16-year study period. This compares with Tay3 who analysed oral biopsies from 1993 to 1997, reviewing a total of 2,057 reports, from which 1,986 separate diagnoses were recorded. Dimba et al.7 reported a 4-year study of oral biopsies in a pathology laboratory at the University of Nairobi Dental Hospital, in Kenya, which included 548 samples. Finally, Jones and Franklin14 studied 44,000 oral and maxillofacial pathological specimens, from adults ≥17 years of age, which had been submitted for diagnosis to a laboratory over a 30-year period (1973–2002).
The data obtained in our sample showed a slightly higher number of biopsies in female patients compared with male patients, consistent with the findings reported by others4., 15., 16.. This could reflect a larger female population in the north of Portugal (according to the Census of 2011). By contrast, when analysing only the OPMD and neoplasm groups, we observed that such lesions more commonly affected male patients, which has been found in other studies5., 6..
In this study, patients in all age groups analysed were affected by oral and maxillofacial lesions, but there was a peak in the incidence of such lesions in the sixth decade of life. This pattern was not true for all groups of lesions, as OPMDs and neoplasms were more common in older patients, whereas non-neoplastic lesions were more common in younger patients. This is in accordance with previous reports15., 21., 22., 23., 24..
The reactive lesion group was the most common pathological group. Fibroepithelial polyp was particularly common, representing 12% of the entire sample. It was seen most commonly in the fifth decade of life, mainly in female subjects and located most often on the buccal mucosa, which is in accordance with data in the literature3., 14., 16., 17., 25..
Indeed, fibroepithelial polyp was the most commonly identified in this study. This is not surprising because the oral cavity is a unique organ that is often subjected to multiple traumatic and pathological stimuli, such as fractured teeth, maladapted prostheses, malocclusion and other dental problems.
Inflammatory odontogenic cysts were the most common lesions in the cystic and odontogenic tumours group, representing 8.2% of the total sample. A higher number of cases was seen in the maxilla. By contrast, the second most common cyst – the follicular cyst – was more prevalent in the mandible. When the analysis was focussed on the group of young patients only, the follicular cyst was the most prevalent type of lesion, as observed by Ha et al.18. Mucoceles were the second most prevalent type of lesion in this group, and were most commonly observed on the labial mucosa of male patients, as reported by others14., 26..
The most common autoimmune lesion was Sjögren's syndrome (n = 18), which was more prevalent in female patients, in accordance with the literature25., 27.. The elevated number of cases of this lesion on the labial mucosa reflects the most common site for minor salivary gland biopsies.
Regarding OPMDs, leukoplakia (n = 76) was the most prevalent, constituting 2.4% of the total sample, which is in line with several reports4., 11., 14.. The authors elected to include lichen planus as an OPMD, as suggested by Warnalulasuryia et al.21. Although leukoplakia is a clinical term, given the importance of this lesion as a potentially malignant disorder, we chose to include this diagnosis within the OPMD group. This gave us a greater understanding of the frequency of OPMDs in this population21. Following histological diagnosis, we reviewed the clinical history to confirm the diagnosis of oral leukoplakia. Nevertheless, it is possible that some cases of leukoplakia, for which clinical information in the pathological report and the clinical history were missing, could therefore be included under the designation of epithelial hyperplasia or hyperkeratosis.
The most common benign neoplasm was pleomorphic adenoma, followed by squamous cell papilloma. Indeed, these two benign neoplasms were also those most reported by Jones and Franklin14, although they reported squamous papilloma as the more prevalent lesion. Regarding salivary glands only, pleomorphic adenoma was the most common benign tumour, most frequently located in major salivary glands, especially the parotid gland, followed by Warthin's tumour; these results are consistent with the literature27., 28..
Malignancy represented 15% of the overall sample, which is similar to that reported by Ali and Sundaram29, but higher than that reported by Jones and Franklin14 and Tay3. The most common malignancy was squamous cell carcinoma, which is consistent with several reports4., 6., 16., 17., 29.. We consider that this result clearly shows that biopsies are vital for the diagnosis of such a prevalent tumour. There was a predilection for the tongue as this was the most commonly affected site (32.9%), and there was also an association with male gender and age 70–79 years. This is consistent with other reports4., 5., 23., 24., 29.. When we analysed the most commonly occurring lesions according to gender and age, interestingly, squamous cell carcinoma was the most prevalent lesion in male patients and in the elderly group of patients. However, we must bear in mind that oral cancer, in both young adults and in female subjects, is rising in several parts of the world, including Portugal. In the last decade, an increasing trend for oral cancer in the Portuguese population has been reported, especially in female subjects30.
Regarding salivary gland malignant neoplasms, the mucoepidermoid carcinoma and adenoid cystic carcinoma were the most common malignant tumours, as observed by Correa et al.15. This slight predominance of mucoepidermoid carcinoma over adenoid cystic carcinoma is in accordance with the reports from Jones and Franklin14 although in contrast to the inverse frequency of these two neoplasms in another study17.
The results of the present study must be interpreted in light of the limitations of this type of retrospective analysis. We acknowledge the limitations of not subdividing some of the locations of the lesions. Moreover, the selected sample may not represent the Oporto population as it is focussed on a hospital-based population. Nevertheless, this is a public and central hospital that treats the general population of Oporto city, including the patients referred to a stomatology centre, hence a large spectrum of diseases are encountered. We consider that this is shown by the 150 different diagnoses seen in this series. It is important to note that we only evaluated biopsied lesions, and therefore oral lesions, that did not undergo a biopsy, were not included in the results. Nevertheless, a strength of this study is the inclusion of the histological description, which proves the accuracy of diagnosis compared with those studies for which the diagnosis is only clinical. Moreover, we described the predominant location for each lesion, which we consider to be important towards a better understanding of the epidemiology of the various oral lesions. To the best of our knowledge, this study is the first large-scale analysis of oral cavity biopsies taken from a sample population in northern Portugal.
Conclusion
The lesions that most commonly affected the oral cavity were non-neoplastic, with the fibroepithelial polyp being the most common lesion of the entire study sample. Squamous cell carcinoma was the second most frequent diagnosis, and was especially common in male patients between 60 and 69 years of age. This large sample therefore provides useful information about the frequency and distribution of oral lesions over a period of 16 years. It also allows a useful comparison with other countries. We believe that the data presented here will be useful in formulating differential diagnoses, and this will be of particular interest to pathologists, oral/maxillofacial surgeons and general dental practitioners.
Acknowledgements
This work was supported by grants (AdOralLeuk-CESPU-2016 and MitOralC-CESPU-2016) from the Cooperativa de Ensino Superior Politécnico e Universitário (CESPU). The authors would like to thank the Pathology Department of Hospital de Santo António (to Vicente Gonçalves, Isabel Calhim and José-Ramón Vizcaíno), and Prof. Oliveira Torres for excellent assistance in this study.
Conflict of interest
No potential conflicts of interest declared.
Supporting Information
Table S1. Number of inflammatory lesions/ diagnoses distributed by gender, age and predominant site.
Table S2. Number of infective lesions/ diagnoses distributed by gender, age and predominant site.
Table S3. Number of cystic lesions/ diagnoses distributed by gender, age and predominant site.
Table S4. Number of reactive lesions/ diagnoses distributed by gender, age and predominant site.
Table S5. Number of autoimmune or metabolic lesions/ diagnoses distributed by gender, age and predominant site.
Table S6. Number of congenital or development disorders/ diagnoses distributed by gender, age and predominant site.
Table S7. Number benign neoplasms/ diagnoses distributed by gender, age and predominant site.
Table S8. Number of malignant neoplasms/ diagnoses distributed by gender, age and predominant site.
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