The cumulative evidence from histopathological-related cross-sectional investigations on oral and maxillofacial lesions gives accurate data with negligible clinical diagnosis biases. These studies also emphasize the prevalence, incidence, and prognosis of a variety of diseases. Because local populations have diverse risk factors, georeferencing is especially important in this procedure .
For the first time, the present study offered a comprehensive evaluation of oral and maxillofacial pathology in an Egyptian pediatric population. Although this study only reveals the relative frequency of oral and maxillofacial lesions in this population, rather than the actual prevalence, it is valuable to both pathologists and pediatric dentists through determining the characteristics of these lesions in children and adolescents that provides the basis for proper diagnosis and treatment. Also, it can guide the differential diagnoses of pathology commonly seen in children [8, 10, 11].
Over 21 years, about 17.5% of all cases submitted for the histopathological examination were from children under the age of 18 years which was consistent with the following studies [10,11,12,13]. On the contrary, other studies reported that pediatric oral biopsies were less than 10% of all cases [8, 14,15,16]. This can be attributed to the difference in inclusion criteria, including age range or locations, population’s genetic background, geographical area, study period, and type of institution .
According to previous studies [6, 18, 19], four age groups were included in the present study to represent a true pediatric population. Also, a smaller pediatric age range was chosen in order to concentrate on the incidence of lesions observed in the newly-erupted permanent dentition and its associated growth and development of its supporting structures [19, 20].
About 37.2% of patients were found in the age group of 11–15 years and 30.2% in the age group of 16–18 years which were in agreement with the previous studies [6, 19, 21]. This finding can be explained by the fact that children and adolescents develop rapidly which affects the growth potential of neoplasms and cysts, as well as rendering this population more likely to acquire inflammatory lesions. Also, this phase is characterized by intense odontogenic activity, a fact that may be related to the occurrence of numerous lesions .
Another explanation is that older pediatric patients present a higher frequency of lesions, not only as a consequence of the epidemiological features of each disease but also because clinicians tend to postpone biopsies or surgeries considering that most of the pediatric lesions are reactive or benign in nature .
The present study showed an almost equal distribution between sexes similar to several studies [6, 11, 19, 22]. This fact may be attributed to the concern and care of the family about the oral health of children and adolescents, irrespective of sex .
The majority of the cases were found in the gingiva (31.9%), according to the site distribution analysis which was consistent with the following studies [17, 22]. On the contrary, several studies reported the lips as the most commonly affected site, representing 34.5% of the lesions [14, 15] and other studies reported the maxilla to be the most affected site for all types of oral and maxillofacial pathology [23, 24]. The variation in the distribution of oral and maxillofacial pathology by anatomical position can be due to the absence of standardization regarding the analysis of anatomical locations affected by oral and maxillofacial lesions .
According to the findings of this study, the prevalence of oral and maxillofacial lesions in children has increased over the years with almost half of the cases 549 (49.5%) were centered in the period from 2014 to 2019. This elevation in the number of pediatric biopsies can be related to genetic factors and changes in lifestyle. Also, this may suggest a higher awareness of pediatric oral health in our country .
There was no agreement on the classification of oral lesions into groups and subgroups in retrospective epidemiological studies of oral lesions from children's biopsies . In the current study, obtained pathological diagnoses were grouped into 11 categories according to the classification proposed by World Health Organization  and Neville et al. .
Regarding the lesions categories, reactive soft tissue lesions were the most prevalent category in the present study (35.8%) which were in accordance with the following studies [6, 17, 24]. This finding may be attributed to their symptomatic nature compared to other lesions .
The majority of reactive lesions in the present study were in the 11–15 years age range similar to the previous studies [17, 19, 28]. Most of these lesions developed on the gingival mucosa, indicating the involvement of tooth pathology and status of dentition in the pathogenesis of at least some of them .
Moreover, pyogenic granuloma was the most frequently encountered lesion in this category followed by peripheral giant cell granuloma, and irritational fibroma. They also were ranked the 2nd, 3rd, and 4th most common lesions in the study population. These findings were consistent with the previous studies [24, 29, 30] and can be attributed to poor oral hygiene and calculus formation [17, 22].
On the contrary, the benign soft tissue lesions represented only (3.2%) of the lesions where hemangioma was the most common connective tissue benign tumor among the study sample and ranked the 18th in accordance with several studies [17, 22, 24].
This can be justified by the fact that many cases of hemangioma are clinically diagnosed, and not always be biopsied. Therefore, the occurrence of hemangioma might be even higher than the number of cases reported .
The odontogenic cysts including both inflammatory and developmental were the second and the third most prevalent categories in the present study representing 19.2% and 8.4% respectively. The prevalence of odontogenic cysts (27.6%) was higher in comparison to non-odontogenic cysts (1%) as reported in the majority of studies [11, 30, 31].
In the present study, the majority of cystic lesions were observed in the 11–15 years age range followed by the 16–18 years age range which was consistent with the previous studies [17, 31]. These lesions were commonly diagnosed in the mandible followed by the maxilla which was in agreement with the previous studies [17, 22].
The inflammatory radicular cyst was the most encountered lesion in the inflammatory odontogenic cyst category and ranked the 1st most common lesion in the study population which was in line with the following studies [8, 22, 30]. This finding may be explained by the high prevalence of dental caries and unsatisfactory oral health conditions, which unfortunately are still common in less developed countries [8, 15].
However, several studies reported a lower prevalence of radicular cyst . This could be attributed to the fact that most radicular cyst cases are detected and treated clinically rather than being sent for a biopsy on a regular basis, particularly if the lesion is removed and disposed of after tooth extraction of the primary dentition [13, 15].
The reactive salivary gland pathology represented the fourth prevalent category among the study sample (5.5%) which was similar to several studies [6, 8]. It is considered the most frequent lesion of the salivary glands with a greater presence in children who are particularly vulnerable, especially in the lower lip area, mainly due to its etiological association with traumatic factors .
Mucous extravasation cyst (mucocele) accounted for the majority of reactive salivary gland pathologies and ranked the 5th most common lesions in the study sample which were in accordance with several studies [23, 29, 30]. The high incidence of mucus extravasation phenomenon could have resulted from trauma, such as lip or cheek bite, to the salivary glands .
Even though salivary tumors are generally uncommon in study populations (1%), the ratio of benign to malignant salivary tumors was 1:1. Therefore, any persistent swelling of unknown etiology within the salivary glands requires urgent investigation .
Benign epithelial odontogenic tumors represented the highest prevalence among odontogenic tumors (4.8%) where ameloblastoma was the most prevalent lesion in the benign odontogenic tumor category representing 2.8% of the study sample and ranked the 10th most common lesion among submitted samples which were in accordance with several studies [11, 15]. On the contrary, other studies reported that odontoma was the most common odontogenic tumor which ranked second to ameloblastoma in our study [8, 22].
This can be explained by the fact that most odontomas are asymptomatic lesions and the majority of people in developing countries do not undergo routine radiographic examination. Only when the lesion produces symptoms or disfigurement would patients seek medical attention .
Giant cell lesions (4.4%) and fibro-osseous (3.4%) bone lesions represented the major categories in bone pathology while benign bone pathology represented only 0.9% of the lesions. Central giant cell lesions and ossifying fibroma had the higher occurrence in their categories and ranked the 7th and 9th most common lesions. These findings were in accordant with the following studies [21, 30] and can be attributed to the fact that those lesions cause jaw expansion and this causes patients to seek medical attention .
Periapical lesions represented 47 (4.2%) of the total lesions where periapical granuloma presented as the most encountered lesion in its category and ranked the 6th most common lesion in the present study which was in line with the previous studies [10, 32]. This could be explained by the fact that the anatomy of primary teeth could help the faster progression of pulp pathology into the periapical area .
Oral lesions that conceal underlying systemic disorders like immunologic diseases were rare among pediatric oral pathology representing only 0.1% of lesions which was consistent with a previous study .
Despite the majority of lesions observed in this pediatric group are benign and require minor treatment, it is important to note that oral malignancies do occur in children at a rate equivalent to global trends. Malignant lesions represented 1.7% of total biopsies in the study population, where 26.3% of them were lymphoma, 21.1% were Mucoepidermoid carcinoma, and 15.8% were Osteosarcoma. These findings were consistent with several studies [8, 23, 29].
Other studies described a higher prevalence of malignant lesions in children, which was probably influenced by the endemic character of certain neoplasms such as Burkitt’s lymphoma [22, 29, 30].
The frequency of oral and maxillofacial pathological lesions among Egyptian children increased over the years but still showed a similar trend to that reported in previous studies. The majority of lesions detected were benign in nature with a very low number of malignant lesions. The majority of the lesions were in the category of reactive and inflammatory lesions with most occurring in the third age group (11–15 years).
In conclusion, the prevalence of oral and maxillofacial pathological abnormalities in Egyptian children grew with time but remained consistent with earlier researches. The vast majority of lesions discovered were benign, with only a few malignant tumors. Most of the lesions were reactive and inflammatory, with the majority of them appearing in the third age group (11–15 years).