| Abstract|| |
Objectives: To report a case of central odontogenic fibroma (COF) with immunohistochemical study.
Clinical Presentation: We describe a case of epithelium-rich type of COF in the posterior region of the mandible of a 39-year-old woman. Immunohistochemical examination showed the odontogenic epithelium to be positive for high-molecular-weight cytokeratins, vimentin and CD99, and negative for CAM5.2. The stroma contained some myofibroblasts and many fibroblast-like cells positive for CD99.
Conclusion: Our immunohistochemical findings, and especially the positive expression of vimentin from the epithelial cells of COF suggests that these cells are primordial. Last but not least, the presence of a relative small number of myofibroblasts in the stroma justifies the non-aggressive behavior of the neoplasm and supports that a part of stromal collagen of COF is produced by these cells.
Keywords: Central odontogenic fibroma, CD 99, cytokeratins, immuno-histochemistry, myofibroblasts, odontogenic tumors, vimentin
|How to cite this article:|
Iordanidis S, Poulopoulos A, Epivatianos A, Zouloumis L. Central odontogenic fibroma: Report of case with immunohistochemical study. Indian J Dent Res 2013;24:753-5
Central odontogenic fibroma (COF) is a rare benign tumor of the jawbones with an asymptomatic slow growth resulting in cortical expansion and accounts for 6.1% of all central odontogenic tumors.  The recent WHO  histological typing of odontogenic tumors distinguishes COF into the epithelium-poor type (formerly termed simple type) and epithelium-rich type (formerly termed WHO type). Two variants of COF have been reported, the central granular cell odontogenic fibroma and the central odontogenic fibroma with giant cells. However, Gardner et al.  suggested that the central granular cell odontogenic fibroma is a separated entity and the central odontogenic fibroma with giant cells could represent a central giant cell granuloma that exhibits an incidental finding of odontogenic epithelium within a fibrous connective tissue stroma. Search of the literature revealed only one immunohistochemical study of COF.  Consequently the immunohistochemical study of our COF case was performed on purpose to investigate the immunohistochemical profile of the odontogenic epithelium of the tumor and especially of its ectomesenchyme.
|How to cite this URL:|
Iordanidis S, Poulopoulos A, Epivatianos A, Zouloumis L. Central odontogenic fibroma: Report of case with immunohistochemical study. Indian J Dent Res [serial online] 2013 [cited 2019 Oct 17];24:753-5. Available from: http://www.ijdr.in/text.asp?2013/24/6/753/127627
We describe a recent case of COF located in the posterior region of the mandible of a 39-year-old woman, the immunohistochemical findings and review of the literature excluding the central granular odontogenic fibroma and central odontogenic fibroma with giant cells.
| Case Report|| |
A 39-year-old woman had been referred us by her dentist following the conventional orthopantomography that revealed a radiolucency associated with an impacted lower left third molar. The clinical examination was normal and the dental and medical histories of the patient were unremarkable. Radiographic examination showed the presence of unilocular radiolucency, measuring 2.5 × 1.5 cm, and extending after the distal root of the lower left second molar to the ramus in relation to the crown of a impacted third molar that was displaced to the ramus [Figure 1]. The provisional radiographic diagnosis was ameloblastic fibroma, ameloblastoma, COF, and dentigerous cyst. The lesion was resected under local anesthesia with the third molar. The surgery was completed by curettage of the remaining bone bed. There has been no recurrence at 1 year follow up.
Sections were stained with hematoxylin/eosin and immunohistochemistry was performed using the streptavidin-biotin complex method and the Ventana autostainer (Ventana Medical Systems, Tuscon, Ariz, USA). [Table 1] summarizes the primary antibodies used, their clone, concentration, incubation time, temperature, and resource. The immunohistochemical panel included antibodies (Dakocytomation, Glostrup, Denmark) against high-molecular-weight cytokeratins (34bE12, dilution 1:20), CAM 5.2 (5D3, dilution 1:100), vimentin (V9, dilution 1:100), α-smooth muscle actin (1A4, dilution 1:100) and CD99 (12E7, prediluted). Antigen retrieval was performed for vimentin using microwave and citrate buffer 0.01M for 15 min at 92°C and for CAM 5.2 and high-molecular-weight cytokeratins using protease I (Sigma, St. Louis, MO, USA) in 0.05 M phosphate buffer for 8 min at 37°C. Examination of sections stained with hematoxylin/eosin showed the presence of cellular fibroblastic connective tissue interwoven with less cellular areas. Numerous islands of odontogenic epithelium and occasional dysplastic foci of cementum were also present. The lesion was not encapsulated [Figure 2]a. Based on these results diagnosis of epithelium-rich type COF was made. The immunohistochemistry showed the odontogenic epithelium to be positive for high-molecular-weight cytokeratins (CKs 1, 5, 10, 14), negative for CAM 5.2 cytokeratins (CKs 8, 18), and focally positive for vimentin [Figure 2]b and c. Alpha-smooth muscle actin was positive in some dispersed spindle-shaped cells in the stroma [Figure 2]d. The odontogenic epithelium and many dispersed fibroblast-like cells in the stroma were positive for CD99 [Figure 3].
|Figure 1: Orthopantomogram showing the unilocular radiolucent lesion in the mandible|
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|Figure 2: (a) The lesion is composed of bundles of interlacing collagenous fibers interspersed with varying amounts of fibroblasts and islands of odontogenic epithelium. H and E ×200. (b) The odontogenic epithelium expresses high-molecular-weight cytokeratins. Streptavidin-biotin complex method ×200. (c) Some odontogenic epithelial cells are positive for vimentin. Streptavidin-biotin complex method ×200. (d) Dispersed spindle-shaped cells in the stroma are positive for ƒ¿-smooth muscle actin (arrows). Streptavidin-biotin complex method ×400|
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|Figure 3: The odontogenic epithelium and some fibroblast-like cells in the stroma express CD99 (arrows). Streptavidin-biotin complex method ×200|
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| Discussion|| |
The epithelium-rich type of COF is composed of cellular fibroblastic connective tissue interwoven with less cellular and often vascular areas. Islands or strands of inactive odontogenic epithelium are an integral component that may be sparse but are often conspicuous. Foci of dysplastic cementum or osteoid or dentin are present.  The histological results of our case fulfill the criteria of epithelium-rich type of COF. In our case the expression of high-molecular-weight cytokeratins from the odontogenic epithelium generally agrees with the cytokeratin AE1/AE3 positivity reported in a previous study.  The lack of CAM5.2 expression from the odontogenic epithelium suggests that this epithelium does not belong to the embryonary or simple epithelia. In the other side, the expression of vimentin from some odontogenic epithelial cells supports that these cells are primordial.  The positive reaction of α-smooth muscle actin in some spindle-shaped cells in the stroma supports the presence of myofibroblasts. The presence of myofibroblasts in COF was described in an electron microscopic study  but was not found immunohistochemically in another report.  The evaluation of myofibroblasts in some odontogenic cysts and tumors suggested that there is a correlation between their number and the biological behavior of these lesions.  Therefore, the small number of myofibroblasts that was found in our case concurs with the non-aggressive behavior of COF. Furthermore, because myofibroblasts are involved in the synthesis of extracellular matrix, obviously a part of stromal collagen of COF is produced by these cells. CD99 is a surface protein encoded by MIC-2 gene in the short arm of the sex chromosome and is expressed in Ewing's sarcoma, lymphoblastic lymphomas, primitive peripheral neuroectodermal tumors, and islet tumors. To the authors' knowledge CD99 has not been investigated previously in odontogenic tumors. In the current study the positive expression of CD99 from the odontogenic epithelium and many fibroblast-like cells in the stroma is explained from the neuroectodermal origin of COF.
The most recent literature review by Daniels et al . in 2004 revealed 70 COF cases including one case of their own. Since then two report cases , have been published and the addition of the current case brings to 73 the number of cases. Data analysis of these 73 cases showed that the age of patients ranged from 4 to 80 years with a mean of 36 years, a male to female ratio of 1:1 and equal distribution between maxilla and mandible. In the maxilla the most common location was in the anterior region (71%) and in the mandible in the posterior region (75%). Except these 73 cases, in 2006 Buchner et al.  studied the odontogenic tumors from northern California and reported 15 cases of COF. According to this study the age of patients ranged from 11 to 50 years with a mean age of 36 years, a male to female ratio of 15:1 and highest frequency of occurrence in the fifth decade of life. There was no significant predilection for the location either in the maxilla or in the mandible. In the maxilla the most common location was in the anterior region (66%) and in the mandible in the posterior region (71%). Radiologically the majority of COFs is seen as unilocular and radiolucent area (55% and 88%, respectively) and causes tooth displacement (55%).  Moreover, the patient's clinical characteristics (age, location of the lesion, radiological findings) in the present case were in agreement with the recent literature review findings. The mode of treatment of COF is enucleation. The recurrence of COF is uncommon. However, Ramer et al . reported a 12.8% (5 out of 39 cases) rate of recurrence. Although the tendency toward recurrence is relatively low, postoperative patient follow-up for 5 years is advisable.
In conclusion our immunohistochemical findings, and especially the positive expression of vimentin from the epithelial cells of COF, suggest that these cells are primordial. Last but not least, the presence of a relative small number of myofibroblasts in the stroma justifies the non-aggressive behavior of the neoplasm and supports that that a part of stromal collagen of COF is produced by these cells.
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Department of Oral Medicine and Oral Pathology, Dental School, University of Thessaloniki, Thessaloniki
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3]