Immunohistochemical Comparative Study of Aggressive and Non-aggressive Central Giant Cell Lesions of the Jaws Based on the Tenascin-C Expression Profile.

The purpose of this study was to compare the immunohistochemical expression of tenascin-C (Tn-C) regarding clinicopathological variables and its association with the clinical behavior of central giant cell lesions (CGCLs). Forty-eight paraffin-embedded samples of CGCLs were selected. Based on clinical and radiographic features, the lesions were classified as aggressive (A-CGCLs) and non-aggressive (NA-CGCLs) subtypes. Histological assessment included the microvessel count (MVC), multinucleated giant cell (MGC) count, and the proportion of tissue area involved by mononuclear stromal cells/interstitial fibrosis. Immunoreactivity, immunolocalization, and distribution patterns of Tn-C were studied immunohistochemically. The association between Tn-C expression and clinicopathological characteristics was analyzed separately and adjusted for confounders using logistic regression models. A significantly greater proportion of cases with moderate-to-intense, intracellular, and diffuse staining of Tn-C was observed in A-CGCLs. CGCLs with a size ≥3.3 cm, fast growth, cortical disruption, high MVC/MGC counts, and low interstitial fibrosis showed a significantly greater frequency of moderate-to-intense, intracellular, and diffuse staining. Logistic regression analysis indicated a strong/independent association of these three immunohistochemical parameters with the aggressiveness of lesions. These data appear to suggest a possible role for Tn-C in the etiopathogenesis of CGCLs of the jaws, where its upregulation might favor the destructive behavior of A-CGCLs.

Florid Cemento-Osseous Dysplasia with a Concurrent Glandular Odontogenic Cyst.

The presence of non-odontogenic cysts associated with benign fibro-osseous lesions of the jaws has been well documented. However, literature is scant when describing benign fibro-osseous lesions with associated odontogenic cysts. This case report highlights the presence of a concurrent developmental odontogenic cyst, glandular odontogenic cyst with extensive squamous metaplasia, in a patient with florid cemento-osseous dysplasia (COD). The postulated pathogenesis of these synchronous lesions is discussed along with a review of current literature. Surgical treatment is discouraged for florid COD, however, radiological follow-up is recommended, especially in lesions with associated cysts.

Shotgun metagenome sequencing identification of a set of genes encoded by Actinomyces associated with medication-related osteonecrosis of the jaw.

Medication-related osteonecrosis of the jaw (MRONJ) is intractable and severely affects a patient's quality of life. Although many cases of MRONJ have been reported in the past decade, the disease pathophysiology is unclear and there are no evidence-based therapeutic strategies. MRONJ usually features bone inflammation and infection. Prior studies that explored the association between MRONJ and microbial infection used the culture-based approach, which is not applicable to hundreds of unculturable taxa in the human oral microbiome, or 16S ribosomal RNA gene sequencing, which does not provide quantitative information of the abundance of specific taxa, and information of the presence, abundance, and function of specific genes in the microbiome. Here, deep shotgun metagenome sequencing (>10 Gb per sample) of bulk DNA extracted from saliva of MRONJ patients and healthy controls was performed to overcome these limitations. Comparative quantitative analyses of taxonomic and functional composition of these deep metagenomes (initially of 5 patients and 5 healthy controls) revealed an average 10.1% increase of genus Actinomyces and a 33.2% decrease in genus Streptococcus normally predominant in the human oral microbiota. Pan-genome analysis identified genes present exclusively in the MRONJ samples. Further analysis of the reads mapping to the genes in the extended dataset comprising five additional MRONJ samples and publicly available dataset of nine healthy controls resulted in the identification of 31 genes significantly associated with MRONJ. All these genes were encoded by Actinomyces genomic regions. Of these, the top two abundant genes were almost exclusively encoded by Actinomyces among usual taxa in the human oral microbiota. The potential relationships of these key genes with the disease are discussed at molecular level based on the literature. Although the sample size was small, this study will aid future studies to verify the data and characterize these genes in vitro and in vivo to understand the disease mechanisms, develop molecular targeted drugs, and for early stage screening and prognosis prediction.

Simple bone cyst: description of 60 cases seen at a Brazilian School of Dentistry and review of international literature

BACKGROUND: The aim of this study was to describe the relative frequency and the main demographic and clinic-radiographic features related to patients diagnosed with Simple bone cyst (SBC) in an Oral Diagnosis Service in Southeast Brazil and present a review and discussion of international literature on this topic. MATERIAL AND METHODS: SBC cases from our service encompassing the period between 1978 and 2017 were selected. In addition, a literature search was performed in the Pubmed/MEDLINE online electronic database published between 1951 and 2019. RESULTS: A total of 2,459 cystic lesions were documented in our service, thus 60 patients were diagnosed with the SBC representing 2.4% of all jaw cystic. Most of cases were asymptomatic. Multiple SBC lesions were seen in two patients (3.4%) and association with cemento-osseous dysplasia was seen in one female patient (1.7%). A total of 793 cases were enrolled in this literature review. CONCLUSIONS: The SBC is an asymptomatic lesion often discovered in routine image exams in young patients. The unilocular, well defined margin with scalloped appearance is characteristic and helps the definition of diagnosis. This review suggests a different epidemiologic trend concerning to the sex and it confirms the posterior region of mandible as the more frequent location. The conservative treatment with limited exploration and curettage remains as the gold-standard treatment

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Dystrophic calcification and respiratory metaplasia in the epithelial lining of odontogenic cysts: a study of 362 odontogenic cysts in a Brazilian population and literature review.

PURPOSE: Main study: undertake a histological study of odontogenic cysts (OC) to determine the prevalence of dystrophic calcification and metaplasia to respiratory epithelium on a Brazilian population. LITERATURE REVIEW: to review the literature for studies that investigated the prevalence of respiratory metaplasia and dystrophic calcification on OC. METHODS: Main study: a retrospective histopathological evaluation was made of the archives from a pathology laboratory. A total of 362 cases diagnosed as OC were identified; they were analyzed by two expert observers to determine the presence of dystrophic calcification and respiratory metaplasia. The association with sex, age and anatomic location was performed through statistical analysis. LITERATURE REVIEW: a critical literature review was undertaken. Two main electronic databases (PubMed and LILACS) were searched. Retrospective studies of histological evaluation that determined the prevalence of epithelial metaplasia and dystrophic calcification on OC, with at least 10 cases, were included; their findings were summarized and discussed. RESULTS: Main study: the histological evaluation of OC revealed the presence of respiratory epithelium in 25 cases (6.9%) and dystrophic calcification in 24 cases (6.6%). Positive association was found to dystrophic calcification on residual cyst and age; respiratory metaplasia on OC and sex; respiratory metaplasia on residual cyst and gnatic bone; respiratory metaplasia in OC and gnatic bone; dystrophic calcification in OC and anatomic site of mandible. LITERATURE REVIEW: eleven studies were included in the literature review, and respiratory metaplasia ranged from 0.0% to 19.2% while dystrophic calcification ranged from 2.5% to 40.5%. CONCLUSIONS: the histological evaluation of this study found 6.9% of prevalence of respiratory metaplasia and 6.6% of dystrophic calcification, which is in accordance with the literature reviewed. Therefore, these phenomena must be taken into account in routine diagnosis services.

Central giant cell granuloma: A clinicopathological and immunohistochemical study of macrophages, blood vessels, lymphatic vessels and regulatory proteins.

OBJECTIVE: This study seeks to investigate immunohistochemical parameters that could distinguish non-aggressive Central giant cell granuloma (CGCG) from aggressive CGCG, two groups of lesions which differ in their clinical and radiographic features and prognosis. MATERIAL AND METHODS: 12 cases of non-aggressive CGCG and 11 cases of aggressive CGCG were investigated and associated the immunohistochemical expression of macrophages (CD68 and CD163), blood vessels (CD34 and CD105), lymphatic vessels (D2-40) and regulator proteins (p63 and Ki-67). Clinical and radiographic features were also studied. RESULTS: Associations between all proteins in non-aggressive and aggressive CGCG were not significant (p > 0.05). With respect to non-aggressive CGCG, there were no significant correlations, while in aggressive CGCG there was a significant positive correlation between CD68 and CD163 (p = 0.031), between CD34 and D2-40 proteins (p = 0.04), whereas a significant negative correlation was observed between CD105 and CD68 (p = 0.040). However, regardless of aggressiveness of CGCG, there was a significant positive correlation between CD68 and CD163 (p = 0,04). Among the clinical and immunohistochemical aspects, only the symptomatology was a significant risk factor for the occurrence of aggressive CGCG (OR = 12.00/p = 0.016). CONCLUSION: Macrophages and angiogenesis contribute to their maintenance and development of CGCG. In addition, immunohistochemistry used here was not able to differentiate their aggressiveness. However, symptomatology was proved to be a risk factor for the occurrence of aggressive CGCG. It is possible that clinical features, particularly symptomatology, represent the most appropriate parameter to attempt to distinguish GCCG.

Benign Alveolar Ridge Keratosis: Clinical and Histopathologic Analysis of 167 Cases.

Benign alveolar ridge keratosis (BARK), the intraoral counterpart of cutaneous lichen simplex chronicus, is a reactive hyperkeratosis caused by trauma or friction that presents as a poorly demarcated white papule or plaque on the keratinized mucosa of the retromolar pad or alveolar ridge mucosa (often edentulous). This is a clinical and histopathologic analysis of BARK including evaluation of p53 expression in selected cases. One hundred and sixty-seven cases of BARK were identified from 2016 to 2017 and 112 (67.1%) occurred in males with a median age of 56 years (range 15-86). The retromolar pad was affected in 107 (64.1%) cases and the edentulous alveolar mucosa in 60 (35.9%) cases, with 17.4% of the cases presenting bilaterally. BARK showed hyperkeratosis often with wedge-shaped hypergranulosis and occasional focal parakeratosis. The epithelium exhibited acanthosis and surface corrugation with tapered rete ridges often interconnected at the tips. The study for p53 performed in 12 cases showed less than 25% nuclear positivity. BARK is a distinct benign clinicopathologic entity caused by friction, which should be clearly distinguished from true leukoplakia, a potentially malignant disorder.

Evaluation of SPECT/CT in the assessment of inflammatory jaw pathologies.

PURPOSE: Since accurate diagnosis of inflammatory jaw diseases is still challenging, this study investigated the performance of three phase bone scintigraphy including SPECT/CT in the assessment of correct diagnosis and size of the affected bone tissue. METHOD: This retrospective study contained 31 patients with suspected jaw-related osteoradionecrosis, osteomyelitis or medication-related osteonecrosis of the jaw, which underwent 3-phase bone scintigraphy including SPECT/CT. Results were reviewed by two nuclear medicine physicians. Positive cases received surgery; negative ones were followed-up for six months. Both served as reference standard. Inflamed bone length was measured in the SPECT/CT images and postoperatively by a pathologist. RESULTS: 19 out of 20 positive cases and 10 out of 11 negative ones were classified correctly by SPECT/CT (sensitivity 95 %, specificity 91 %, accuracy 94 %, positive predictive value 95 %, negative predictive value 91 %). Regarding the length of affected bone, no significant difference (p = 0.23) could be observed between SPECT/CT and postoperative obtained values. Both correlated significantly (r = 0.86, p = 0.0001). CONCLUSION: SPECT/CT can safely detect different kinds of inflammatory jaw pathologies compared to other conventional imaging modalities. Lack of specificity of conventional scintigraphy ranging from 17 % to 71 % in earlier studies could be improved by adding CT-analysis. Additionally, SPECT/CT assists the surgeon in determining the expansion of the process (with focus on the length) preoperatively and thereby optimizing surgery planning.

Differential expression of nicotinamide N-methyltransferase in primary and recurrent ameloblastomas and odontogenic keratocysts.

BACKGROUND: Odontogenic tumours are a group of rare heterogeneous diseases that range from hamartomatous tissue proliferations to benign and malignant neoplasms. Recurrences can occur after 10 years, so long-term clinical and radiological follow-up is required. The study of the molecular mechanisms involved in the development of these lesions is necessary to identify new prognostic markers. In this study, we evaluate the possible role of nicotinamide N-methyltransferase (NNMT) in ameloblastomas (AM) and odontogenic keratocysts (OKC). MATERIALS AND METHODS: A total of 105 surgical specimens of primary and recurrent lesions were obtained from 55 patients (25 AM, 30 OKC). In particular, 50 AMs (25 primary, 25 recurrences) and 55 OKCs (30 primary, 25 recurrences) were retrieved. We carried out immunohistochemical analyses to evaluate the cytoplasmic expression of NNMT, measuring the percentage of positive cells and the value of NNMT expression intensity. RESULTS: NNMT expression was significantly higher in recurrent than primary AMs (P = .0430). This result was confirmed by staining intensity, showing more cases with moderate/intense staining in recurrent AMs (P = .0470). NNMT expression was significantly lower in recurrent than primary OKC (P = .0014). Staining intensity showed more cases with moderate/intense staining in primary OKCs (P = .0276). CONCLUSIONS: This report is the first to evaluate NNMT expression in odontogenic lesions and to demonstrate a differential expression in recurrent AMs and OKCs, suggesting that there is potential for use of NNMT as prognostic marker.

Giant Cell Lesions of the Jaws:A Review and Comparative Histopathological Study.

BACKGROUND AND OBJECTIVES: Giant cell lesions (GCLs) are rare lesions which prominently feature multinucleated giant cells in their histology. They include central giant cell granuloma (CGCG), giant cell tumour of bone (GCT), peripheral giant cell granuloma (PGCG), Cherubism (CHB), e.t.c. This study reviewed the clinico-demographic parameters of GCLs of the jaws and assessed the giant cells. METHODS: This was a retrospective study examining the histopathology records of which part of the body of two tertiary institutions. All entries of cases diagnosed as GCLs were retrieved and data were extracted. Also, the giant cells in tissue sections were assessed. Data were analysed using SPSS Inc. version 20 while Chi square test was used to test for association. This was considered significant quand p < 0.05. RESULTS: Over the study period, 2,862 biopsy reports were reviewed. GCLs constituted 48(1.7%) and M: F ratio was 1:1.6 while majority occurred in the 2nd and 3rd decades. The mandible was the most common site recording 27(56.3%) cases and CGCG was the most frequently diagnosed GCL constituting 22(45.8%). Assessment of the giant cells revealed CGCG had predominantly large giant cells, a dense dispersal of giant cells and irregularly shaped giant cells, while CHB mainly had large giant cells with dense dispersal, but round shaped giant cells. CONCLUSION: GCLs are rare lesions commonly seen in females in the 2nd and 3rd decades of life with preference for the mandible. CGCG was the most commonly encountered lesion, while the giant cells in CGCG and CHB were similar in size as well as dispersal.

A Comparative Analysis of p63 Expression in Giant Cell Tumour (GCT), Central Giant Cell Granuloma (CGCG) and Peripheral Giant Cell Granuloma (PGCG).

Giant cell tumour (GCT) is locally aggressive benign neoplasm of long bones whereas giant cell granulomas; central giant cell granuloma (CGCG) and peripheral giant cell granuloma (PGCG); are tumour-like conditions of the oral cavity. This study aimed to evaluate and compare the immunohistochemical expression of p63 in GCT, CGCG, PGCG and determine whether p63 can be used as a diagnostic, prognostic and differential biomarker between these entities. Histopathologically diagnosed 10 cases of GCT, 20 cases of CGCG and 20 cases of PGCG were subjected to p63 immunohistochemical staining. The percentage of p63-positive cells was semi-quantitatively assessed on the whole section. Intergroup comparison was done using Kruskal-Wallis test and one-way ANOVA. The value p < 0.05 was considered to be statistically significant and value p < 0.01 was considered to be statistically highly significant. p63 immunoexpression was seen in 100% (10/10) cases of GCT whereas CGCG and PGCG revealed the complete absence of p63 immunopositivity. These results showed a highly significant difference in p63 expression between GCT, CGCG and PGCG (p < 0.01). No difference was noted between CGCG and PGCG. GCT is a distinct entity when compared with CGCG and PGCG. Even aggressive CGCG also did not show p63 immunopositivity, so it is not a prognostic marker. Also, p63 cannot differentiate between CGCG and PGCG.

Dental pulp exposure, periapical inflammation and suppurative osteomyelitis of the jaws in juvenile Baltic grey seals (Halichoerus grypus grypus) from the late 19th century.

The systematic analysis of museum collections can provide important insights into the dental and skeletal pathology of wild mammals. Here we present a previously unreported type of dental defect and related skull pathology in five juvenile Baltic grey seals that had been collected in the course of a seal culling program along the Danish coast in 1889 and 1890. All five skulls exhibited openings into the pulp cavities at the crown tips of all (four animals) or two (one animal) canines as well as several incisors and (in one animal) also some anterior premolars. The affected teeth showed wide pulp cavities and thin dentin. Pulp exposure had caused infection, inflammation, and finally necrosis of the pulp. As was evidenced by the extensive radiolucency around the roots of the affected teeth, the inflammation had extended from the pulp into the periapical space, leading to apical periodontitis with extensive bone resorption. Further spreading of the inflammation into the surrounding bone regions had then caused suppurative osteomyelitis of the jaws. The postcanine teeth of the pathological individuals typically had dentin of normal thickness and, except for one specimen, did not exhibit pulp exposure. The condition may have been caused by a late onset of secondary and tertiary dentin formation that led to pulp exposure in anterior teeth exposed to intense wear. Future investigations could address a possible genetic causation of the condition in the studied grey seals.

A comparative study of osteopontin and MMP-2 protein expression in peripheral and central giant cell granuloma of the jaw / Estudo comparativo da expressão das proteínas osteopontina e MMP-2 no granuloma central e periférico de células gigantes de mandíbula

Abstract Introduction: Oral peripheral and central giant cell granulomas are lesions with little-known etiology and pathogenesis. Objective: The aim of this study was to compare matrix metalloproteinases-2 and osteopontin protein expression in the multinucleated giant cells and mononuclear cells of the peripheral and central giant cell granuloma lesions. Methods: In this retrospective study, the presence of matrix metalloproteinases-2 and osteopontin in 37 cases of central giant cell granuloma and 37 cases of peripheral giant cell granuloma paraffin blocks were assessed by streptavidin-biotin immunohistochemistry. Independent sample t-test, Chi-square, Mann-Whitney tests and Spearman's rank correlation coefficient were used. Results: The osteopontin was expressed in both multinucleated giant cells and mononuclear cells in all cases of peripheral and central giant cells granulomas. However, the matrix metalloproteinases-2 expression was positive in 86.5% of giant cells and it was positive in all of mononuclear cells in peripheral giant cells granuloma. In central giant cells granulomas, 91.8% of giant cells and all mononuclear cells were positive for matrix metalloproteinases-2 marker. Percentage and Intensity of staining were significantly higher in central than peripheral giant cells lesions, for both markers (p ˂ 0.05). Conclusion: This study showed that the expression of osteopontin in giant cells supports the theory of osteolcastic nature of these cells. Also, the presence of osteopontin and matrix metalloproteinases-2 in mononuclear cells may indicate the monocyte-macrophage origin of these cells, as the differentiation of the precursors of the mononuclear stromal monocyte/macrophage to osteoclasts is possibly affected by the expression of osteolytic factors. Also, may be differences in biological behaviors of these lesions are associated with the level of osteopontin and matrix metalloproteinases-2 expression.

Resumo Introdução: Os granulomas periféricos e centrais de células gigantes são lesões com etiologia e patogênese pouco conhecidas. Objetivo: Comparar a expressão das proteínas metaloproteinases da matriz-2 e osteopontina nas células gigantes multinucleadas e células mononucleares no granuloma periférico e central de células gigantes. Método: Neste estudo retrospectivo, a presença de metaloproteinases da matriz-2 e osteopontina em 37 casos de granuloma central de células gigantes e 37 casos de granuloma periférico de células gigantes em blocos de parafina foi avaliada por imuno-histoquímica pela estreptavidina-biotina. Foram usados teste t para amostra independente, teste de qui-quadrado, Mann-Whitney e coeficiente de correlação de Spearman. Resultados: A osteopontina foi expressa em células gigantes multinucleadas e células mononucleares em todos os casos de granuloma periférico de células gigantes e granuloma central de células gigantes. No entanto, a expressão de metaloproteinases da matriz-2 foi positiva em 86,5% de células gigantes e foi positiva em todas as células mononucleares em granuloma periférico de células gigantes. Em granuloma central de células gigantes, 91,8% das células gigantes e todas as células mononucleares foram positivas para o marcador metaloproteinases da matriz-2. A porcentagem e intensidade de coloração em granuloma central de células gigantes foram significantemente maiores do que em granuloma periférico de células gigantes para ambos os marcadores (p ˂ 0,05). Conclusão: Este estudo mostrou que a expressão de osteopontina em células gigantes apoia a teoria da natureza osteoclástica dessas células. Além disso, a presença de osteopontina e metaloproteinases da matriz-2 em células mononucleares pode indicar a origem dos monócitos-macrófagos dessas células, uma vez que a diferenciação dos precursores do monócito/macrófago estromal mononuclear em osteoclastos é possivelmente afetada pela expressão de fatores osteolíticos. Além disso, as diferenças nos comportamentos biológicos dessas lesões estão associadas ao nível de expressão de osteopontina e metaloproteinases da matriz-2.

ACE Gene Variant Causing High Blood Pressure May Be Associated With Medication-related Jaw Osteonecrosis.

The association of the high blood pressure D variant of the angiotensin-converting enzyme (ACE) gene with medication-related jaw osteonecrosis (MRONJ) is described in two Greek patients. The first patient, a 73-year-old man, took zolendronate, 4 mg/100 ml IV once per month for two years for prostate cancer and bone metastases. Three months after drug discontinuation, extraction of the first premolar was performed. After the intervention, he suffered from osteonecrosis of the mandible. He presented with hypertension and genetic testing revealed that he was homozygous for the high blood pressure D variant of the ACE gene. The second patient, a 65 years old woman, took denosumab, 120 mg subcutaneously once per month for 6 months for possible bone metastases from breast cancer. Three months after extraction of the first molar, she suffered from MRONJ. He also presented with hypertension and genetic testing revealed that she had the high blood pressure D variant of the ACE gene in a heterozygous state, which moderately predisposes to hypertension. To our knowledge, this is the first report indicating that genetic predisposition to hypertension may increase risk for MRONJ.

Application of Autologous Platelet-Rich Plasma on Tooth Extraction Site Prevents Occurence of Medication-Related Osteonecrosis of the Jaws in Rats.

This study evaluated the effects of local application of autologous platelet-rich plasma (PRP) on the tooth extraction site of rats presenting the main risk factors for medication-related osteonecrosis of the jaw (MRONJ). For seven weeks, senile rats were submitted to systemic treatment with vehicle (VEH and VEH-PRP) or 100 µg/Kg of zoledronate (ZOL and ZOL-PRP) every three days. After three weeks, the first lower molar was extracted. VEH-PRP and ZOL-PRP received PRP at the tooth extraction site. Euthanasia was performed at 28 days postoperatively. Clinical, histopathological, histometric and immunohistochemical analyses were carried out in histological sections from the tooth extraction site. ZOL showed lower percentage of newly formed bone tissue (NFBT), higher percentage of non-vital bone tissue (NVBT), as well as higher immunolabeling for TNFα and IL-1ß. In addition, ZOL presented lower immunolabeling for PCNA, VEGF, BMP2/4, OCN and TRAP. VEH and ZOL-PRP showed improvement in the tooth extraction site wound healing and comparable percentage of NFBT, VEGF, BMP2/4 and OCN. Local application of autologous PRP proved a viable preventive therapy, which is safe and effective to restore tissue repair capacity of the tooth extraction site and prevent the occurrence of MRONJ following tooth extraction.

A comparative study of osteopontin and MMP-2 protein expression in peripheral and central giant cell granuloma of the jaw.

INTRODUCTION: Oral peripheral and central giant cell granulomas are lesions with little-known etiology and pathogenesis. OBJECTIVE: The aim of this study was to compare matrix metalloproteinases-2 and osteopontin protein expression in the multinucleated giant cells and mononuclear cells of the peripheral and central giant cell granuloma lesions. METHODS: In this retrospective study, the presence of matrix metalloproteinases-2 and osteopontin in 37 cases of central giant cell granuloma and 37 cases of peripheral giant cell granuloma paraffin blocks were assessed by streptavidin-biotin immunohistochemistry. Independent sample t-test, Chi-square, Mann-Whitney tests and Spearman's rank correlation coefficient were used. RESULTS: The osteopontin was expressed in both multinucleated giant cells and mononuclear cells in all cases of peripheral and central giant cells granulomas. However, the matrix metalloproteinases-2 expression was positive in 86.5% of giant cells and it was positive in all of mononuclear cells in peripheral giant cells granuloma. In central giant cells granulomas, 91.8% of giant cells and all mononuclear cells were positive for matrix metalloproteinases-2 marker. Percentage and Intensity of staining were significantly higher in central than peripheral giant cells lesions, for both markers (p˂0.05). CONCLUSION: This study showed that the expression of osteopontin in giant cells supports the theory of osteolcastic nature of these cells. Also, the presence of osteopontin and matrix metalloproteinases-2 in mononuclear cells may indicate the monocyte-macrophage origin of these cells, as the differentiation of the precursors of the mononuclear stromal monocyte/macrophage to osteoclasts is possibly affected by the expression of osteolytic factors. Also, may be differences in biological behaviors of these lesions are associated with the level of osteopontin and matrix metalloproteinases-2 expression.