ORAL AND MAXILLOFACIAL PATHOLOGY e128 Abstracts PRIMORDIAL ODONTOGENIC TUMOUR: CLINICOPATHOLOGIC ANALYSIS OF SIX CASES OF A PREVIOUSLY UNDESCRIBED ENTITY Adalberto Mosqueda Taylor1, Fabio Ramoa Pires2, José Manuel Aguirre Urizar3, Roman Carlos Bregni4, José Mario De La Piedra Garza5, Rafael Martínez Conde3, Guillermo Martínez Mata6, Sergio J. Carreño Álvarez7, Henrique Martins Da Silveira8, Bruno Santos De Barros Dias8, Oslei Paes De Almeida9, 1Departamento de Atención a la Salud, Universidad Autónoma Metropolitana Xochimilco, México D.F.; 2Patologia Bucal, Faculdade de Odontologia, Universidade do Estado do Rio de Janeiro, Brazil; 3Departamento de Estomatología II. UFI 11/25. Universidad del País Vasco/EHU, España; 4Centro Clínico de Cabeza y Cuello/Hospital Herrera-Llerandi, Guatemala City, Guatemala; 5División de Estudios de Posgrado e Investigación, Facultad de Odontología, Universidad Nacional Autónoma de México, México D.F.; 6Facultad de Odontología, Universidad Autónoma de Chihuahua, México; 7 Hospital Central Sur de Alta Especialidad, Pemex, México, D.F.; 8Cirurgia Bucomaxilofacial, Hospital Universitário Pedro Ernesto, Universidade do Estado do Rio de Janeiro, Brazil; 9Faculdade de Odontologia de Piracicaba, UNICAMP, Brazil Objective: To describe the clinico-pathologic and immunohistochemical features of six tumours that do not fulfill the criteria of any of the currently classified odontogenic tumours. Study Design: Collaborative retrospective clinico-pathological study. Results: Three males and three females, mean age 11.5 yr. All tumours were composed of variably cellular to loose fibrous tissue similar to dental papilla, surrounded by epithelium resembling the internal epithelium of the enamel organ. Mesenchymal tumoral tissue was only positive for vimentin (S-100, SMA, CD 34 and desmin negative). Ki-67 expression was very low (<2%). Epithelium was positive for CK14 and CK19, but negative for CK18 and CK20. Subepithelial hyalinization was seen in two cases. Conclusions: These findings differ from ameloblastic fibroma, odontogenic myxoma, odontogenic fibroma, and hyperplastic dental follicles. All cases were surgically removed, with clear demarcation from the surrounding bone and no recurrence after follow-up ranging from 3 months to 20 years. The term primordial odontogenic tumour is proposed. Keywords: Odontogenic tumour, dental papilla, dental follicle ESTABLISHMENT OF THERAPEUTIC EFFECT ASSESSMENT ANIMAL MODEL OF FIBROUS DYSPLASIA Sunao Sato1, Yuri Noda1, Kaori Oya1, Yu Usami2, Mitsunobu Kishino1, Yuzo Ogawa1, Satoru Toyosawa1, 1Department of Oral Pathology, Osaka University Graduate School of Dentistry, Osaka, Japan; 2Clinical Laboratory, Osaka University Dental Hospital, Osaka, Japan Objective: Fibrous dysplasia (FD) is common fibro-osseous lesions and activating point mutation of the alpha subunit of the stimulatory G protein gene (GNAS) causes FD. For FD patients, main medical treatment is surgical resection. Design of new effective ways of pharmacologic intervention relies on appropriate FD animal model, however, to date there is no animal model suitable for reproduction of FD lesion. Study Design: Here, we produced cell line with GNAS point mutation and transgenic mice expressing GNAS point OOOO March 2015 mutation with osteoblast specific. We examined the feature of these cell line and transgenic mice. Results: Cell line with GNAS point mutation showed the similar gene expression with FD patients and transgenic mice had bone morphological change compared to wild type mice. Conclusions: These results suggest that cell line with GNAS point mutation and transgenic mice with osteoblast specific GNAS point mutation are a useful FD model for pharmacologic intervention. Keywords: fibrous dysplasia, animal model, cell line, bone CLINICOPATHOLOGICAL STUDY IN ELEVEN CASES OF ORAL GIANT CELL FIBROMA AND FREQUENCY OF THIS ENTITY IN THE UNIVERSITY OF CHILE BETWEEN 1980 AND 2013 Daniela Adorno Farias, Andrea Maturana Ramirez, Marcela Farías Vergara, Juan Pablo, Aitken Saavedra, Ana Ortega Pinto, Department of Oral Pathology and Medicine, Chile University, Santiago, Chile Oral giant cell fibroma is a benign fibrous neoplasm characterized by the presence of mono-, bi- or multinucleate spindleshaped or stellate giant cells that are mainly found in subepithelial connective tissue and does not seem to be associated with chronic irritation. The purpose of this research was to report the main clinical and histological features of 11 patients who were referred and treated in the Oral Pathology and Medicine Service by oral giant cell fibromas. Besides we also determined the frequency of this entity in oral mucosal biopsies sent to the Service of biopsies of the University of Chile between 1980 and 2013. Keywords: oral giant cell fibroma, Clinicopathological features, frequency EVALUATION OF ORAL SYMPTOMS AND COMPLAINTS AS A RESULT OF RADIOTHERAPY IN PATIENTS WITH HEAD AND NECK CANCER REFERRING TO TABRIZ IMAM REZA HOSPITAL IN 2013 Ali Taghavi Zenouz1, Mahdi Vatankhah1, Alireza Naseri2, Masoumeh Mehdipour1, Mahdi Khalili1, Marziyeh Aghazadeh1, Masoumeh Johari3, 1Oral Medicine Department of Dental Faculty; 2 Radiation Oncology Department of Imam Reza Hospital; 3 Radiology Department of Dental Faculty, Tabriz, Iran Objective: The present study was conducted to evaluate persistence and frequency of symptoms and signs of patients with head and neck cancers, undergoing radiotherapy. Study Design: Oral symptoms of 89 patients were assessed by QLQ-C30 questionnaire (a modified version according to cultural points) just after the radiotherapy and 3 months later. Data was analyzed by t-test, and Wilcoxon and Kruskal-Wallis tests using SPSS 15. Results: The most frequent permanent and temporary symptoms were xerostomia (95.2%) and mucositis, respectively. The overall symptoms (burning mouth, liquid dysphagia, hoarseness, altered speech and altered sense of smell) improved over time, with no significant differences between pre-treatment period and 3-month post-treatment interval. Sticky saliva, solid dysphagia and xerostomia improved, while a significant difference remained compared to baseline (p<0.001). Conclusions: Oral complications related to mucositis ameliorated over time but the overall symptoms that were influenced by salivary changes were persistent. Keywords: head and neck cancer, radiotherapy