Ossifying fibroma of the upper jaw: Report of a case and review of the literature

PÉREZ-GARCÍA S, BERINI-AYTÉS L, GAY-ESCODA C. OSSIFYING FIBROMA OF THE UPPER JAW: REPORT OF A CASE AND REVIEW OF THE LITERATURE. MED ORAL 2004;9:333-9.

SUMMARY

A number of processes generically referred to as benign fibro-osseous lesions comprise different disorders such as fibrous dysplasia, sclerotizing osteomyelitis and ossifying or cementing fibroma. These processes are all characterized by the existence of a vascular fibroblastic stroma, with the production of a calcified matrix ranging from bone to cementum. Ossifying fibroma involves slow-evolving growth with deforming swelling generally arising in the mandible, with possible early dental displacement. From the radiological perspective the disorder generally manifests as a well defined and delimited, unilocular radiotransparency, as a radiotransparent image with central opacifications, or as multilocular transparencies. The lesions exceptionally can be radiopaque.
We present the case of a 22-year-old male presenting for evaluation of a three-month, asymptomatic tumor mass in the anterior sector of the upper jaw. Radiologically, the lesion appeared as a radiotransparent zone surrounded by a poorly delimited sclerotic halo. The definitive diagnosis following surgical resection of the lesion was ossifying fibroma. The case is discussed, and a review is provided of the literature on the subject.

Key words: Ossifying fibroma, cemento-ossifying fibroma, benign fibro-osseous lesions.

INTRODUCTION

The cells of the periodontal ligament are able to generate a great variety of benign neoplasms. The lesions generally appear in dentate zones of the upper and lower jaws. In some cases the neoplasms derive from ectopic periodontal ligament cell remains, and can manifest in unusual locations. When present in such ectopic locations, these lesions can become expansive or aggressive, with the need for surgical management (1).

A number of authors have suggested that ossifying and/or cementing fibromas are benign fibro-osseous lesions originating in the periodontal ligament - as a result of which they would constitute histological variants of one same pathological process (1-6). However, the presence of lesions microscopically identical to these but located in other body regions such as the orbit, frontal bone, ethmoid bone, and sphenoid or temporal bone, have caused persistent controversy over their origin (7).

The lesions are designated differently, depending on the type of tissue identified (2). Thus, the term ossifying fibroma is used if the predominant component is bone, while cementing fibroma is defined by the presence of curvilinear trabecular structures or spherical calcifications. In turn, lesions characterized by the presence of bone and cementum are referred to as cemento-ossifying fibroma. However, the terms ossifying fibroma and cementing fibroma are merely academic designations (2,8), since authors such as Eversole et al. (2) have failed to identify histological differences between them. For this reason the nomenclature can be simplified by referring to all lesions of this group as ossifying fibromas (2,9).

The term fibro-osseous lesion does not refer to a concrete diagnosis but rather to a group of pathological processes of similar radiological appearance and histopathology (5). The classification in this case depends on the clinical, radiological and histological findings (10).

A number of classifications have been proposed to group these pathological processes. Huebner et al. (5) cited the classification proposed by Edwards et al. (11) in 1984. Posteriorly, Waldron (12) proposed another classification which has likewise been cited by a series of investigators (4,5).

In general, ossifying fibroma is an asymptomatic lesion until growth causes swelling and moderate deformation (13-15). Displacement of the teeth (3,14) can be an early clinical manifestation (14). The teeth associated with the lesion preserve their vitality and may present root resorption (3). The lesion is relatively slow-growing (13-16), as a result of which the overlying cortical bone layer and mucosa remain intact (3,14), and thus the tumor may be present for a number of years before a diagnosis is made (14).

The treatment of ossifying fibroma consists of surgical excision with extended resection depending on the size and location of the lesion (16,17).

The present study describes a case of unilocular ossifying fibroma in a 22-year-old male, with a review of the literature on the subject.

CLINICAL CASE

A 22-year-old male without antecedents of interest was referred to the Service of Oral Surgery and Implantology of the Dental Clinic (Barcelona University, Spain) by his dentist, for evaluation of an asymptomatic swelling in the vestibular zone of the upper jaw between 1.1 and 1.2. At the time of the first visit, the lesion had been present for the previous three months.

The clinical examination revealed painless bulging of the vestibular cortical bone of the upper jaw, measuring approximately 2 cm in diameter, with a hard consistency and located between the upper central and right lateral incisors. These teeth presented a diastema. The crown of 1.2 was positioned in mesioversion (Figure 1). The overlying gingival tissue was normal in appearance. Cold testing of dental vitality proved positive for 1.1, 1.2 and 1.3.

Orthopantomography and periapical X-rays revealed a mixed image. The center of the lesion appeared radiotransparent, while the margins were more radiopaque. The lesion extended from the bone crest to apical level of the adjacent teeth, with root divergence being identified at this level, together with mesioversion of the crown of 1.2 (Figure 2). Computed tomography clearly visualized the alteration of normal bone architecture at the level of 1.1 and 1.2, with vestibular cortical bulging in the region of the incisors, and of the palatal cortical component at 1.1 level. The mixed lesion encompassed both incisors and extended apically at the level of 1.2 (Figure 3).

A trephine incisional biopsy was made and the specimen was sent to the Pathology Service. The findings were compatible with ossifying fibroma of the upper jaw. Resection of the lesion was thus decided, with the extraction of 1.1 and 1.2. The histological study of the global lesion revealed the presence of fusiform cellular elements arranged in bundles, with variable-size and randomly distributed amorphous calcifications. There was no evidence of malignant disease in any of the submitted tissue fragments. These findings and the clinical observations confirmed the tentative presurgical diagnosis (Figure 4). The patient was subjected to clinical and radiological follow-up after excision of the lesion, to discard possible relapses. In the meantime, the patient is wearing a provisional removable prosthesis, with satisfactory esthetic results. The possibility of bone grafting in the zone will be proposed at a later date, for the placing of osseointegrated implants to restore the edentulous zone.

DISCUSSION

Yih et al. (4) and Sciubba et al. (18) attributed the first description of this disorder to Menzel, in 1872. In 1927, Montgomery (19) first used the term ossifying fibroma, by which the lesion is currently known. The name has subsequently also been used by other authors (5,8,18). Until 1948 it was believed that fibrous dysplasia and ossifying fibroma were either the same entity or variants of one same lesion (8). That year, Sherman and Sternberg (20) published a detailed description of the clinical, radiological and histological characteristics of ossifying fibroma, and since then most researchers coincide in considering the two lesions to be different clinical entities (2,8, 17,20).

Ossifying fibroma is a benign bone neoplasm of the jaws composed of fibrous connective tissue with variables amounts of metaplastic bone and mineralization. The lesion is generally encapsulated - a fact that serves to distinguish it from fibrous dysplasia, which may exhibit similar clinicopathological features (13,21,22). Although the lesion is preferentially located in the jaws, it can also be found elsewhere - including the frontal, ethmoid, sphenoid and temporal bones or orbit, as well as in the anterior cranial fossa (7,9).

Some authors have pointed to antecedents of trauma in the area of the lesion, the performance of tooth extractions, and the prior existence of periodontitis, as possible triggering factors (15).

Ossifying fibroma of the jaws generally manifests in the third or fourth decades of life (2,3,15-18,21), though younger patients have also been affected (14,23). Thus, Slootweg and Müller (10), in a review of all published cases of ossifying fibroma, found the mean patient age at presentation to be 25 years. Juvenile ossifying fibroma is a more aggressive variant affecting the craniomaxillofacial bones, with rapid growth and presentation in individuals under 15 years of age (21,23). Our patient was 22 years old, i.e., somewhat below the mean age established for ossifying fibroma.

The disease is more frequent in females (2,3,6,9,14,15,17,18,21), with a male-to-female ratio of between 1.5:1 (18) and 5:1 (2,17), depending on the source. However, Su et al. (6) observed that in the 10-29 years age range, where a greater prevalence of cemento-ossifying fibromas has been recorded, no such female predilection appears to exists.

The lesion is mainly observed at mandibular level (2,3,9,10,14-18,21), and more commonly in the molar and premolar zone. It appears as a hard, localized and slow-growing mass that displaces the teeth, though the latter remain vital and the overlying mucosa is characteristically intact (3). Tooth displacement and root resorption are common findings (2,3,16-18). Root divergence is recorded in 17% of cases (2,3,17, 18), while root resorption is seen in 11% (2,3,17) to 44% (18), depending on the author. In our patient the diastema between 1.1 and 1.2 was present before the lesion became clinically manifest; as a result, we are uncertain whether the lesion induced early tooth displacement, or was not the actual cause of the diastema. The teeth implicated in the lesion remained vital and no root resorption was observed.

The size of the lesion can range from 0.2-15 cm (6); in our case the fibroma measured 2 cm in diameter.

Radiologically, the lesion appears well circumscribed, and is initially seen as an osteolytic image followed by gradual transformation into a mixed lesion - in exceptional cases becoming radiopaque (3,15,16). Some authors (13,18), including Eversole et al. (2), have described two basic radiological patterns: a unilocular radiotransparency with or without radiopaque foci, and a multilocular radiotransparency. The former presentation is more common - the radiotransparency overlapping the roots, with neither divergence nor root resorption (17). Su et al. (6) commented that the radiological image most often associated with cemento-ossifying fibroma corresponds to a well defined radiotransparency with or without a sclerotic margin, and often accompanied by cortical expansion. Orthopantomography and periapical X-rays in our patient revealed the presence of a poorly defined unilocular lesion, with a central radiotransparent zone and a more opaque peripheral area, located between the roots of 1.1 and 1.2. Computed tomography in turn afforded a clearer image of the lesion as a radiotransparent zone containing irregular radiopaque foci. Expansion of the vestibular cortical layer was also visualized, together with a small palatal cortical bulge at apical level of 1.2.

Considerable controversy remains over the histopathology of ossifying fibroma. Most authors consider fibrous dysplasia and ossifying fibroma to be histologically similar - the sole differentiating feature being a fibrous capsule surrounding the latter, and infrequently observed in the case of fibrous dysplasia (3,13,24). Other authors indicate that ossifying fibroma is characterized by an abundant presence of osteoclasts and osteoblasts, and that on comparing both disorders the trabecular distribution is seen to be more regular in this latter lesion, with fewer collagen and vascular elements, and increased cellularity (12). Likewise, the lesion has been reported to offer four possible hard tissue configurations (2,22): trabeculate, laminar, ovoid-curved deposits and anastomotic curvilinear trabeculae. However, no histopathological features are able to determine the potential aggressivity of the lesion (2,7) or its tendency to recur (2), and no relation has been established between the radiological features of ossifying fibroma and the corresponding recurrence rates (17).

The differential diagnosis must be established with those disorders which due to the patient age, sex, lesion location, clinical features and radiological characteristics may coincide with the parameters observed in our patient.

Sciubba and Younai (18), and MacDonald-Jankowski (9) have indicated that enucleation or curettage as first treatment option affords a recurrence rate of 0-28%. If relapse is identified in the course of follow-up, conservative resection is obligate (18). Some authors are not in favor of radical resection of the lesion, since recurrence in any case is infrequent (14,18); they thus advocate conservative elimination of the lesion, followed by long-term radiological and clinical follow-up (18). En bloc resection would be indicated in cases where recurrence is identified after a first intervention in the form of surgical curettage (19), or in patients with extensive lesions (25). The percentage recurrence rate varies from 6% (3,18) to 28% of cases (6,17). There is no evidence to suggest that ossifying fibroma can undergo malignant transformation (7). Our patient showed no clinical or radiological evidence of recurrence after 8 months of post-resection follow-up. Since the time elapsed from surgery is still short, continued clinical and radiological monitorization is required before deciding osseous reconstruction of the anterior sector of the upper maxilla with sufficient guarantees of non-recurrence.

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