|Year : 2008 | Volume
| Issue : 2 | Page : 68-71
Odontogenic fibroma: An unusual presentation
Jose M Armas1, Keith D Hunter2, William MM Jenkins1
1 Unit of Periodontology, University of Glasgow Dental Hospital and School, Glasgow, United Kingdom
2 Oral Pathology Unit, University of Glasgow Dental Hospital and School, Glasgow, United Kingdom
William MM Jenkins
Department of Periodontology, University of Glasgow Dental Hospital and School, 378 Sauchiehall Street, Glasgow G2 3JZ
Source of Support: None, Conflict of Interest: None
| Abstract|| |
The odontogenic fibroma is a relatively rare, slow-growing, benign odontogenic neoplasm of the jaws, with the potential to recur after excision. It may occur either intraosseously or as a localized gingival overgrowth, in which case it may be mistaken for other more common exophytic gingival lesions. This paper reinforces the importance of radiographic and histological examination for exophytic gingival lesions by describing a recurrent peripheral odontogenic fibroma, presenting in 1986, 1992, and 2003, accompanied on this last occasion by a separate but co-located, central odontogenic fibroma in the underlying alveolar process.
Keywords: Epulis, odontogenic fibroma, odontogenic tumor, peripheral
|How to cite this article:|
Armas JM, Hunter KD, Jenkins WM. Odontogenic fibroma: An unusual presentation. J Oral Maxillofac Pathol 2008;12:68-71
| Introduction|| |
The odontogenic fibroma (OF) is a rare benign neoplasm, representing 1% to 2.5% of oral biopsy specimens.  It occurs either as a central (intraosseous) lesion (COF) or in a peripheral location (POF). The OF is characterized by proliferation of relatively cellular fibrous or fibromyxomatous connective tissue that exhibits variable amounts of odontogenic epithelium, often designated as epithelium-poor or epithelium-rich subtype. Foci of calcification in the form of dentinoid, cementicles, or bone may also be present.  The epithelial component resembles the dental lamina formed during the early stages of odontogenesis.
In the largest survey of odontogenic tumors reported so far, the odontogenic fibroma comprised 2.9% of the total of 1133 lesions and occurred more frequently as a peripheral than as an intraosseous lesion (23 vs. 16 lesions).  Recent reviews have reported an equal incidence of OF in maxilla and mandible, ,, corroborating similar findings by Daley and Wysocki.  The most common site for the POF is the canine/premolar area both in the mandible and maxilla. ,, The most prevalent sites for the COF are the mandibular premolar/molar area and the maxillary canine/premolar area. ,, Age at diagnosis varies widely, with a peak in the third and fourth decades of life. [1-5] There is a slight female predominance. ,
The POF presents as an elevated, exophytic lesion with no radiological changes in the underlying alveolar bone. The COF most often is an incidental radiographic finding, manifested as a unilocular, well-circumscribed radiolucency , but may present within gingival tissue as a peripheral extension of the central lesion. Enucleation and curettage, not radical excision, is the treatment required. 
This paper reports the unusual presentation of two apparently separate but co-located odontogenic fibromas in a patient followed up for 20 years. This report also highlights the importance of radiographic examination of the alveolar process when assessing an epulis, the value of histological examination, the difficulty of reaching a diagnosis, and the importance of appropriate treatment and follow-up.
| Case Report|| |
In 1986, a 30-year-old White woman was referred by her general dental practitioner to Glasgow Dental Hospital and School with a polypoid lesion extending across the interdental gingiva between the maxillary left canine and first bicuspid, firm and pink on its buccal aspect, softer and erythematous palatally. There was widespread gingivitis throughout the dentition, associated with inadequate plaque control but no significant attachment loss. Radiographic examination did not reveal any abnormality of the inter-radicular bone [Figure 1A]. Evidently, during her pregnancies, gingival swelling had occurred at this site but had appeared to resolve. An excision biopsy and histopathological examination were undertaken. This revealed chronic gingivitis associated with a prominent fibrous overgrowth of the underlying connective tissue, consistent with the clinical diagnosis of a resolving pregnancy epulis. She was discharged to her general dental practitioner.
The patient presented again six years later, in 1992, with a similar soft tissue lesion at the same site, larger this time on the palatal aspect (1.2 cm in diameter) than on the buccal. Excision biopsy was undertaken without prior radiography. Histological examination of the specimen again revealed features of fibrous overgrowth consistent with the clinical diagnosis of fibrous epulis. The patient was once again discharged to be followed up by her general dental practitioner.
In 2003, 11 years after her last attendance, the patient returned with another fibrous-looking overgrowth at the same site, extending across the interdental gingiva, more prominent on the buccal aspect, where it measured 1 cm in diameter [Figure 2]. There was, as previously found, widespread gingivitis throughout the dentition, without significant attachment loss. The canine and bicuspid were now separated by a 1-2 mm space. Radiographic examination revealed a well-circumscribed radiolucent lesion occupying the full mesio-distal width of underlying inter-radicular bone, not quite penetrating the alveolar crest and extending 0.8 mm in an apico-coronal direction [Figure 1B].
The soft tissue lesion was excised and a buccal mucoperiosteal flap reflected for access to the bony lesion which had caused thinning of the buccal plate of bone, in the center of which there was a small perforation <5 mm in diameter. The soft tissue contents of the bony cavity were enucleated prior to wound closure. Histopathological examination revealed that both the deep part of the gingival lesion and the intraosseous tissue consisted of a collagenous and myxoid fibroblastic proliferation with strands of odontogenic epithelium dispersed within the fibrous tissue. These appearances were consistent with a diagnosis of odontogenic fibroma of epithelium-poor (simple) type [Figure 4],[Figure 5],[Figure 6],[Figure 7].
Reexamination of the previous two biopsies with cutting of further sections revealed a small number of nests and cords of odontogenic epithelium within bland-looking fibrous tissue resembling the biopsy specimens obtained in 2003, raising the suspicion that these earlier lesions were also POFs.
Healing was uneventful. [Figure 3] shows the operation site six weeks later. Subsequently, the patient was followed up closely, and radiographs were taken at annual intervals, demonstrating complete bone-fill with no loss of crestal bone height. [Figure 1C] shows the radiographic appearance in 2006, almost three years following the last surgical procedure. The space that had developed between the canine and bicuspid closed spontaneously.
| Discussion|| |
The OF occurs with slightly greater frequency as an extraosseous or 'peripheral' lesion,  the most common location for which is the attached gingivae in the canine/premolar region of the mandible and maxilla. ,, The lesion is usually firm to palpation, nontender, and could be easily mistaken for other more common exophytic gingival lesions, such as the fibrous epulis or pyogenic granuloma. Its diagnosis depends on the demonstration of nests and cords of odontogenic epithelium. Taken in isolation, the presence of such epithelial elements, unless plentiful, is of uncertain significance, which was the reason for our first two biopsy specimens yielding diagnoses of reactive gingival lesions. However, in view of the most recent histology and the development of an underlying central lesion, it seems reasonable to assume that the lesion which presented originally in 1986 was an odontogenic fibroma, and the subsequent gingival lesions represent its recurrence. What makes the present case unusual is the initial presence of a gingival lesion overlying a radiographically normal and intact alveolar process within which a COF later developed. When the central lesion first developed is unknown because no further radiographic examination was undertaken for 17 years. Furthermore, it is unclear whether the extraosseous and intraosseous tissue specimens which were removed in 2003 represent two separate lesions which later merged or whether the extraosseous lesion was the peripheral extension of a central lesion. The latter hypothesis would seem the less likely because the alveolar process was radiographically intact when the first lesion, later identified as a POF, appeared in 1986; and because at operation in 2003, the two lesions appeared separate; although this cannot be stated with certainty. One may speculate that these were two separate lesions - one peripheral, the other central - arising from extraosseous and intraosseous remnants of dental follicle. This is believed to be the first report of such an occurrence involving the odontogenic fibroma. There are, nonetheless, similarities with a recent report suggesting an etiological link between a peripheral ossifying fibroma and an underlying COF. 
The OF is a benign neoplasm; and, although rare, it is the second most common odontogenic tumor , after ameloblastoma. Unlike ameloblastoma, it is not locally invasive and therefore treatment is conservative; but complete enucleation or removal, rather than wide local excision, is advised. Because of the relative rarity of these lesions and the lack of published follow-up data from a large series, the OF's potential to recur is unknown. Nevertheless, Daley and Wysocki  reported that out of 18 patients with a POF for whom follow-up data were available, 5 lesions recurred after 1 year, including 2 which recurred at 3 years and 1 which recurred at 4 years. The POF in the present report reappeared 6 years after initial excision and 11 years after the second excision. This is the longest reported time interval between initial excision and recurrence.
This case also demonstrates the importance of radiographic examination of all exophytic gingival lesions to exclude a central component, and of histological examination of their biopsy specimens to establish the diagnosis. Although at first presentation there was no radiographic evidence of such a lesion, it was detected following routine radiography 17 years later, at the time of second recurrence. The third gingival lesion, furthermore, had the clinical appearance of a fibrous epulis although it had the histological appearance of a POF.
| Conclusion|| |
This report demonstrates the potential for recurrence of the POF by describing one such lesion that reappeared after excision on two occasions over a 17-year period, the longest reported time interval between excision and recurrence for this type of lesion. Another unique feature was the co-occurrence of a separate COF in the underlying alveolar process. The unusual presentation of these lesions demonstrates the importance of careful clinical and radiographic examination of all exophytic gingival lesions in order to exclude a central component, and the value of histological examination in reaching a diagnosis.
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[Figure 1A], [Figure 1B], [Figure 1C], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]