Evaluation of cysts and odontogenic tumors over a period of 8 years in a reference medical hospital in Brazil

Objective: This study aimed to evaluate the relative prevalence, demographic distribution and clinical-pathological characteristics of the maxillary odontogenics cysts and tumors of the jaws in a pathology laboratory located in a university hospital in Northeastern Brazil. Methods: An observational and retrospective study was carried out, in which information was collected on histopathological diagnosis, age, gender and location of the lesion of patients who had been diagnosed with odontogenic cysts or odontogenic tumors between 2013 and 2020. Results: Among the 546 specimens, 57 were odontogenic cysts and 41 were odontogenic tumors. The most frequent odontogenic cysts were the odontogenic keratocyst 21 (21.4%) and the root cyst 19 (19.4%). The most frequent odontogenic tumors were ameloblastoma 27 (27.6%) and odontoma 6 (6.1%). Conclusion: The data found in this study are possibly associated with the service assistance profile. Resultados: de las 546 muestras, 57 fueron quistes tumores odontogénicos y 41 fueron tumores odontogénicos. Los quistes odontogénicos más frecuentes fueron el queratoquiste odontogénico 21 (21,4%) y el quiste radicular 19 (19,4%). Los tumores odontogénicos más frecuentes fueron el ameloblastoma 27 (27,6%) y el odontoma 6 (6,1%). Conclusión: Los datos encontrados en este estudio posiblemente estén asociados con el perfil de servicio del servicio.


Introduction
Many studies on oral health are based only on clinical data that, although important, do not inform the actual pathological nature of the lesion. Therefore, studies based on biopsies are essential to determine the prevalence of lesions that commonly affect a given population. Additionally, identifying the frequency of oral and maxillofacial lesions is essential for establishing the diagnosis and treatment of the patient. (Joseph et al., 2019); knowledge of the location, age, and gender predilections of different diseases of the oral cavity is useful with regard to determining their demographic data; and, finally, it is essential for the planning and execution of public health programs. (Alhindi et al., 2019).
Odontogenic cysts and tumors of the jaws represent one of the most prevalent groups of oral and maxillofacial lesions (Açikgöz et al., 2012). Maxillary cysts can be defined as pathological intraosseous cavities filled with fluid, semi-solid or gaseous material, partially or totally covered by epithelial tissue and delimited by a connective tissue capsule. When the cyst develops from remaining odontogenic epithelial tissues, it is called an odontogenic cyst. This category is then subdivided according to its inflammatory or developmental origin. (Philipsen et al., 2006;Nuñez-Urrutia et al., 2010;Demirkol et al., 2014). Odontogenic tumors were first described in the scientific literature in 1869, when Pierre Paul Broca introduced the term "odontoma" to classify a tumor lesion originating from tooth-forming tissues (Philipsen et al., 2006). They correspond to a heterogeneous group of lesions ranging from hamartomas to neoplastic or malignant lesions derived from ectodermal and/or mesenchymal odontogenic tissues (Aregbesola et al., 2018).
Given the different nature of odontogenic cysts and tumors, several consensus meetings have tried to produce a more systematic classification of these lesions, promoted by the World Health Organization (WHO) in 1971 (Philipsen et al., 2006).
Since then, other WHO meetings have reviewed the classifications of these injuries in 1992, 2005 and 2017 (Bianco et al., 2020). Although several case series of odontogenic cysts and tumors have been reported worldwide, few have evaluated and compared the two groups of lesions together. (Daley et al., 1994;Gaitán-Cepeda et al., 2010;Jaeger F et al., 2017). However, the aim of our study was to evaluate the relative prevalence, demographic distribution and clinicopathological characteristics of odontogenic cysts and tumors of the jaws in a pathology laboratory located in a leading university hospital in northeastern Brazil.

Methodology
After approval of the University of Pernambuco Ethics Committee (35920620.7.0000.5192), an observational, descriptive and retrospective study was carried of patients (Lima-Costa & Barreto, 2003) who had been diagnosed with odontogenic cysts or odontogenic tumours between 2013 and 2020 from the Pathology Laboratory, Universitary Hospital Oswaldo Cruz, University of Pernambuco, which is one of the most representative public services of health in Brazil. The study was performed in full accordance with the World Medical Association Declaration of Helsinki.
All lesions were revised by 2 oral pathologists and defined according to the criteria of classification of the World Health Organization published in 2017 (El-Naggar et al., 2017). Information regarding the gender, histopathological diagnosis, age and local of the lesion were collected.
Data were tabulated and statistically analyzed using the Statistical Package for Social Sciences version 20.0 software (SPSS, Chicago, IL). Frequencies and the P-value test were used to compare the distribution of odontogenic cysts and tumors associated with independent variables. They were considered significant when the P value was less than 0.05.

Results
During the study period, a total of 546 specimens from biopsies of head and neck lesions were received in the pathology laboratory of the University Hospital Oswaldo Cruz of the University of Pernambuco, among the 98 cases received histopathological diagnosis of lesion of odontogenic origin, being 57 ( 58.1%) odontogenic cysts and 41 (41.9%) odontogenic tumors (Table 1).
A statistically significant association (p<0.05) was found between the variable anatomical location of the jaws, age and the presence of odontogenic cysts and tumors (Table 4). Odontogenic tumors were less frequent than odontogenic cysts in the maxillary region. However, the occurrence of odontogenic cysts and tumors was significantly greater in the mandible than in the maxilla (p=0.002).
There was no statistically significant association between the distribution of odontogenic cysts and tumors, according to gender and anatomical region. (Table 4).

Discussion
In the period surveyed, 546 lesions were diagnosed in a region of head and neck being 98 (17.94%) of these classified as cysts and odontogenic tumors. Equivalent manner, a study with similar methodology held in the Brazilian Northeast obtained 20.3% (Barros et al., 2019) and another in the Brazilian midfielder obtained 21.22% (Jaeger, 2017). In the meantime, international research diverges from the aforementioned findings, Amrita and employees when analyzing the records of an oral pathology service in Kanpur, India, observed a frequency of only 8.49% for such injuries (Raj et al., 2017). Such a discrepancy of results shows that epidemiological surveys of head and neck lesions in a given geographical area establish the real needs of said population, as well as provide professionals facilities in the elaboration of treatment plans and preventive actions (Karen et al., 2015).
With regard to the prevalence of odontogenic cysts and tumors, it is noted that the cysts are common lesions in the gnatical bones (Açikgöz et al., 2012) and may vary their frequency in the studies between 3.65% to 22.41% (Avelar et al., 2009;Souza et al., 2010;Açikgöz et al., 2012;AlSheddi et al., 2015;Raj et al., 2017). We observed a greater number of cases in males, with no significant difference between odontogenic cysts and odontogenic tumors. This gender distribution was also observed in other studies on odontogenic cysts (Ledesma-montes et al., 2000;Meningaud et al., 2006;Prockt et al., 2008;Tortorici et al., 2008;Açikgöz et al., 2012;Selvamani et al., 2012;Khosravi et al., 2013;Baghaei et al., 2014;Demirkol et al., 2014;Kambalimath et al., 2014) and odontogenic tumors (Lawal et al., 2013;Oginni et al., 2015;Aregbesola et al., 2018). Odontogenic cysts occurred more frequently in the maxilla when compared to odontogenic tumors that occurred more commonly in the jaw, and in accordance with the findings of other population cohorts in odontogenic cysts and odontogenic tumors.
The vast majority of the studies reports a greater frequency of odontogenic lesions in individuals between the second and fourth decade of life (Avelar et al., 2009;Souza et al., 2010;Açikgöz et al., 2012;AlSheddi et al., 2015;Serkerci et al., 2015;Da Silva et al., 2016;Lima-verde-osterne et al., 2017). These data resemble this study, with the highest frequency of cases between the second and the fourth decade of life and the age range ranging from 8 to 81 years.
As for the anatomical location, there was a predominance of cases in jaw when compared to jaw. The information collected are in consensus with other works, where the jaw is considered the most frequent location of cysts (Avelar et al., 2009;Açikgöz et al., 2012;AlSheddi et al., 2015) and odontogenics tumors (AlSheddi et al., 2015;Sekerci et al., 2015;Da Silva et al., 2016;Lima-verde-osterne et al., 2017). It is worth noting that there is a greater chance of being observed cases in the jaw in cysts than in odontogenic tumors (Avelar et al., 2009;Açikgöz et al., 2012;AlSheddi et al., 2015), similar to the data found in this study.
Odontogenic cysts are classified between inflammatory and development (Castro-Núñes, 2015;Speith & Takata, 2018) being the most common radicular and dentigerous representatives, respectively. In the descending order of prevalence, root cysts are (apical, vertical and lateral variant), followed by the odontogenic cyst and odontogenic keratocyst (Avelar et al., 2009;Souza et al., 2010;Açikgöz et al., 2012;AlSheddi et al., 2015). In this study, distinct findings were obtained, since the odontogenic keratocyst was more common than the others. Divergent data is possibly associated with the service care profile, amendment in the classification of this injury by WHO 2017 and professional negligence as to the adequate forwarding of specimen with a diagnostic hypothesis of inflammatory basis for the purposes of histopathological analysis.
In relation to the epidemiological data of odontogenic tumors, ameloblastoma was found more frequently (n = 27) when compared to odontoma (n = 6). When the literature considers these epidemiological variations, the explanation lies in possible ethnic and / or geographical differences (Daley et al., 1994;Arotiba et al., 1997;Lu Y et al., 1998;Santos et al., 2001). It is also common to suggest that ameloblastomas are more common in blacks than in Caucasians (Regezi et al., 1978;Gunhan et al., 1990;Daley et al., 1994;Odukoya, 1995;Arotiba et al., 1997;Lu Y et al., 1998). In an epidemiological study of the odontogenic tumors of two Brazilian institutions, both in the state of São Paulo, was observed that at the dental hospital, of 113 cases, odontomas and ameloblastomas corresponded to 39.4 and 22.12% of odontogenic tumors, respectively. On the other hand, at the medical hospital, 75 cases, 60% were ameloblastomas and only 5.3% were diagnosed as odontomas (Fregnani et al., 2002). It should be considered that in many countries ameloblastomas are usually diagnosed in the Faculty of Dentistry, but the treatment is carried out in a medical hospital. This is not the case of odontomas. However, some comparative studies considering dental and medical institutions help clarify the subject (Gunhan et al., 1990;Mosqueda-Taylor et al., 1997). In a retrospective study of 349 Odontogenic tumors in Mexico, including dental and medical hospitals, no odontoma was treated in the last. Therefore, the data encountered in this study are possibly associated with the service assistance profile (Mosqueda-Taylor et al., 1997).

Conclusion
Knowledge about clinical-pathological distribution of cysts and odontogenic tumors brings benefits to professionals and patients. The best understanding of the behavior and clinical-pathological profile of the cases diagnosed in this reference service in Pathological Anatomy of the State of Pernambuco contributes to the scientific literature with regard to the study of the pathologies of this anatomical region, as well as subsidizing management in decision-making and resources applied in this health care segment. Further studies including large series should be performed in different regions of the world in order to determine the global epidemiologic profile of these lesions.