Epidemiological Analysis of Tongue Lesions in a Tertiary Health Facility in Tanzania

Background: The tongue is susceptible to a multitude of conditions that can be of developmental, neoplastic, or inﬂammatory nature, whose occurrence varies globally by age, sex, and ethnicity. The objective of the present study was to determine the incidence of tongue lesions among cases managed in a tertiary hospital in Tanzania. Methods: This study analyzed histological results of patients with tongue lesions diagnosed between 2016 and 2021. Data on the age and sex of the patients and histological diagnosis were collected. Data analysis was done using Statistical Package for the Social Sciences version 27. Results: A total of 190 samples of tongue lesions were studied and 18 different histological diagnoses were observed. Generally, a majority (84.2%) of the biopsied tongue lesions were malignant. The most common (74.7%) lesions diagnosed were squamous cell carcinoma followed by hemangioma (5.3%). A signiﬁcant association was noted between the nature of the lesions and the age group and sex of the patients. Conclusion: This analysis depicts that tongue lesions are frequently encountered in patients managed in tertiary health facilities in Tanzania. A majority of these lesions are malignant tumors. The sex and age of the patients are determining factors for the occurrence of tongue lesions.


Introduction
The tongue, a muscular organ located within the oral cavity, is responsible for several important functions like speech, chewing, tasting, swallowing, and breathing [1,2].On its dorsal surface, this organ is covered by stratified keratinized squamous epithelium, whereas a non-keratinized epithelium lines its ventral surface [3].It comprises minor salivary glands, nerve endings, fat cells, blood vessels, and lymphoid tissues [3,4].Embryologically, at approximately the fourth week of gestation, tongue development starts.
Initially, from the first pharyngeal arch, a medial swelling (tuberculum impar) is formed, followed by two lateral swellings, which fuse to form the anterior two-thirds of the tongue [5].The posterior third of the tongue arises from a hypobranchial eminence, that is, a median swelling (copula), which emerges from the mesoderm of the second to fourth pharyngeal arches [1,6].
Due to the different embryological origins of the tongue, its vast content of structures, and its anatomical position, the tongue is susceptible to a diverse group of lesions ranging from developmental to neoplastic and inflammatory conditions [3,4].The incidence of tongue lesions varies globally by age, sex, and ethnicity [7,8].
According to age, pediatric patients usually suffer from benign conditions whereas the elderly are prone to malignant tongue lesions [9,10].In India [11] and Nigeria [4], malignant conditions like squamous cell carcinoma of the tongue were predominant, whereas in Thailand [10], the inflammatory conditions were predominantly diagnosed as lesions of the tongue.
Despite the importance of the tongue, generally, a very limited number of studies have reported clinicopathological reviews of histologically diagnosed tongue lesions [4], and of these none is from Tanzania.It is thus not known the exact incidence of tongue lesions and the nature of these lesions among patients who attended a tertiary health facility in Tanzania.Lack of this knowledge hinders clinicians from having a high level of suspicion when they encounter patients with tongue lesions, and this leads to either under-or over-diagnosis of the condition.
Therefore, the objective of the present study was to determine the incidence of tongue lesions among cases managed in a tertiary hospital in Tanzania.

Materials and Methods
This study analyzed the histopathologic reports of patients with tongue lesions managed in a tertiary health facility in Tanzania.The study covered a period of six years starting from 2016, January 2 nd to 2021, December 31 st .The inclusion criteria were all histopathological reports of lesions of the tongue over the stated period, in cases where there were more than one histological report, such as one of pre-surgery incisional biopsy and another for post-surgical excision of the lesion, the postop result was included.Whereas, any report with inconclusive diagnoses or without a final diagnosis and reports of lesions that started from surrounding structures (e.g.floor of mouth) and subsequently spread to the tongue were excluded.
Convenience sampling method was used.The age of patients was categorized into four groups: <18 years (pediatrics), 18-39 years (young adults), 40-59 years (middle-aged adults), and ≥60 years (older adults).For regression analysis, the age was categorized as ≤40 years and >40 years.
The tongue lesions were categorized into their nature as malignant, benign, and non-neoplastic (which included infections and inflammatory and developmental conditions).
The Chi-square tests and One-way Analysis of Variance (ANOVA), where applicable, were utilized to assess the association of patients' age and sex with the nature of the tongue lesion.The  < 0.05 was selected for statistical significance.To ascertain the degree to which the age and sex were related to the nature of tongue lesions, the multivariate logistic regression model was applied.

Sociodemographic of patients
Out of the 1824 histology results of patients diagnosed with orofacial lesions retrieved, 190 (10.4%) belonged to patients who had tongue lesions.The patients' ages at the time of diagnosis ranged from 1 to 84 years, with a mean age of 51.3 (SEM = 1.20) years.The median age was 52 (IQR = 22) years.The middle-aged were predominantly affected (N = 83, 43.7%), and there was a male preponderance (N = 114, 60%) with a female-tomale ratio of 1:1.

The general histological diagnoses
A total of 18 different diagnoses were observed from the 190 tissue samples of tongue lesions.
A majority (N = 160, 84.2%) of the biopsied tongue lesions were malignant.A significant association was observed between the nature of the lesions and the patients' age group (P < 0.05).
Except for benign lesions, the sex of the patient was significantly associated with the nature of the lesion (Table 1).

The malignant tongue lesions
Of the 160 histological reports with diagnoses of malignant lesions of the tongue, 101 (63.1%) were reports of male patients with a male-to-female ratio of 1.7:1.The age range of patients at the time of diagnosis was 8-84 years, with a mean age of 54.2 (SEM = 1.08) years and a median age of 52.5 (IQR = 20) years.The chances of males being diagnosed with a malignant tongue lesion were two times higher than those of female patients and 11 folds higher for individuals aged >40 years (Table 2).
A total of seven types of malignant lesions of the tongue were diagnosed; of these, squamous cell carcinoma predominated (N = 142, 88.8%; Figure 3).

The benign tongue lesions
Benign lesions of the tongue were noted in the histological reports of 14 (7.4%) patients.There was a slight male predilection (male: female = 1.mean age of 25.00 (SEM = 4.94) years and a median age of 26.5 (IQR = 29) years.Individuals aged >40 years were 96% less likely to be diagnosed with a benign tongue lesion (Table 2).

14.3%
).There was one case each of fibromatosis and fibroepithelial polyp.

Non-neoplastic lesions of the tongue
A total of 16 (8.4%)histological reports of patients had final diagnoses indicative of non-neoplastic lesions.Females were more (N = 11, 68.8%) affected than males, with a male-to-female ratio of 1:2.2).Seven histological types of lesions were observed of which chronic inflammation and pyogenic granuloma were the frequent diagnoses (Figure 4).

Discussion
Several epidemiologic studies have pointed out that tongue lesions make up for a significant fraction of oral lesions with varying proportions in different countries [7,8,12].However, to date in Tanzania there is a paucity of documentation on the profile of types of lesions to commonly affect the tongue.Thus, there was a need to study the occurrence of tongue lesions among patients managed in a tertiary health facility in Tanzania.
This health facility, being a national referral center, receives patients from all over the country.
In the present study, around 10% of all biopsied lesions in the orofacial region involved the tongue similar to a report from Iran [13].On the contrary, the prevalence was higher than reports from Nigeria [4] and Iran [12] but lower than findings from Turkey [7] and India [9].The difference in proportion between various epidemiologic studies from different countries may be attributed to factors like genetics, geographical location, study methodology, and sociodemographic status of the population [12,14,15].
Although a multitude of lesions do affect the tongue [4,7,9,12], a great variation in the proportion of lesion types exists between various geographical locations.In the current study, approximately 20 different types of tongue lesions were found of which a majority were malignant, this finding was in line with the report from Nigeria [4].On the other hand, immune-mediated lesions of the tongue were the most frequently diagnosed tongue lesions in Iran [12], while benign tongue lesions were predominantly noted in Turkey [3].The high proportion of malignant conditions among the biopsied tongue lesions in our setting may be attributed to both the clinical practice of the clinicians and the social background of the population.The practice in our setting calls DOI 10.18502/sjms.v19i1.15775tobacco and alcohol to reach the progenitor cell compartment [17], however, also chronic trauma to the tongue may have a role [18].
The findings from this study depicted that the chances of males being diagnosed with a malignant tongue lesion were two times higher than those of female patients, and 11 folds higher for individuals aged >40 years.Although on the contrary, both Alaeddini et al. [12] and Altintas [3] found that there was no sex predilection for the occurrence of malignant tongue lesions and the prevalence was higher in patients aged >40 years.Similarly, Sohal et al. [19] reported that older individuals had higher odds of suffering from oral cancers because of the cumulative effect of carcinogenic substances over time.Several previous studies from Tanzania [20,21] have reported that males are more affected by malignant orofacial lesions (tongue included).Males tend to engage more in risky behavior (alcohol consumption, tobacco use, etc.) than females and are thus prone to malignancies [19].
From the current study, it was depicted that the odds of occurrence of benign lesions in older adults were significantly lower than in young individuals.Since the pathogenesis of neoplastic conditions relies on changes in genes accountable for tumor growth [22], it may be speculated that gene modifications in benign tumors tend to appear during initial years of life.Hence, the number of mutated cells increases rapidly during an individual's growth phase/spout, causing the occurrence of tumors (e.g., hemangioma) to occur early in life.
Squamous cell carcinoma was the most predominant tongue lesion in the current analysis, unlike other reports.In Iran [12], lichen planus was found to be prevalent, while in Turkey [3], squamous papilloma was frequently diagnosed.Reports from Italy [23] and Thailand [10] revealed fibrous reactive hyperplasia, and squamous cell carcinoma were frequent diagnosis.Squamous cell carcinoma is the most prevalent tongue lesion because of its location which exposes it to a large number of carcinogens that pass through the mouth [21], coupled with the fact that the tongue is lined with epithelial cells [19].

Limitations
This study had a few limitations.Firstly, the clinicians might have not sent every excised pathological lesion for histological analysis.This may be so because some lesions were diagnosed based on their clinical appearance.This practice could lead to under-reporting of some lesions like geographic tongue, aphthous ulcers, and various other immune-related conditions.Secondly, it was a single-center study, hence generalizability of the findings is a challenge.Another shortcoming was absence of data about the exact location of each lesion on the tongue.This deficiency has been documented and to overcome this challenge, it has been suggested to design a standard reporting form that will contain all variables of prognostic importance [19].Nevertheless, this study provides valuable information on the types of tongue lesions commonly biopsied in our settings by age and gender.

Conclusion
This analysis depicts that tongue lesions are frequently encountered in patients managed in tertiary health facilities in Tanzania.A high proportion of these conditions are of malignant nature.
3: 1).The age of patients at the time of diagnosis ranged between 1 year and 64 years with a Sudan Journal of Medical Sciences Sohal et al

2 .
The patients' age ranged from22 to 88 years at the time of diagnosis, and the mean age was 45.13 (SEM = 4.98), while the median age was 40.5 (IQR = 29) years.Patients aged 40 years and less were nearly four times more likely to have non-neoplastic conditions of the tongue than those aged above 40, whereas, the odds of males being diagnosed with non-neoplastic tongue lesions were 73% less compared to females (Table

Figure 1 :
Figure 1: Gross view of the ulcerative lesion on the lateral aspect of the tongue which was histologically diagnosed as squamous cell carcinoma.

Figure 2 :
Figure 2: Clinical presentation of the hemangioma involving the dorsal aspect of the tongue.

Figure 3 :
Figure 3: Distribution of different types of malignant tongue lesions according to the frequency of occurrence.

Figure 4 :
Figure 4: Distribution of different types of malignant tongue lesions according to the frequency of occurrence.
The sex and age of the patients are determining factors for the occurrence of tongue lesions.Males and middle-aged patients are predominantly affected.Due to the presence of a large number of conditions affecting the tongue, clinicians should consider histopathological examination of all tongue lesions, as it is the gold standard for confirming the diagnosis and should not rely on clinical examination alone.For better characterization of tongue lesions in the Tanzanian population, multicentric clinical studies should be conducted.

Table 1 :
Overall distribution of patients according to age groups, sex, and the nature of the tongue lesions.

Table 2 :
Crude odds ratio to ascertain the association between age groups and the nature of the tongue lesions.