Cemento-ossifying fibroma of mandibular gingiva:
single case report

GALDEANO-ARENAS M, CRESPO-PINILLA JI, ÁLVAREZ-OTERO R, ESPESO-FERRERO Á, VERRIER-HERNÁNDEZ A. CEMENTO-OSIFYING FIBROMA OF MANDIBULAR GINGIVA: SINGLE CASE REPORT. MED ORAL 2004;9:176-9.

ABSTRACT

We report a case of a woman presenting a giant cemento-ossifying fibroma depending of the mandibular gingivae. The evolution of the process was 20 years. Cemento-ossifying fibroma is a relatively rare tumour classified between fibro-osseous lesions. This lesion appears within the bone although in some occasions it involves the gingivae soft tissues, as the case we present. It is a slow-growing and well-defined tumorous lesion, because of this, it is considered as a benign lesion. The histologic findings alone may be similar to other pathologies such as osteoblastoma, low-grade osteosarcoma and particularly to fibrous dysplasia. An accurate diagnosis requires careful clinical, radiological and histological correlation in order to make an optimal treatment and an excellent outcome.

Key words: Cemento-ossifying fibroma, fibro-osseous lesions, gingiva.

INTRODUCTION

Benign fibro-osseous lesions of the jaws present problems in diagnosis and classification.

The 1992 WHO classification groups under a single designation ( cemento-ossifying fibromas) two histologic types (cementying fibroma and ossifying fibroma) that may be clinically and radiographically undistinguishable(1).

Cemento-ossifying fibroma is a relative rare lesion considered as an osteogenic tumor (non odontogenic) with variable expressiveness. It is defined as a well-demarcated and occasionally encapsulated lesion consisting of fibrous tissue containing variable amounts of mineralized material resembling bone (ossifying fibroma), cementum (cementying fibroma) or both(2,3).

It usually follows a silent clinical course, except of those affecting the gingivae which present as an enlarging mass that progressively grow, finally producing a facial deformity.

Diagnosis requires careful clinical, radiological and histological correlation (1).

CASE REPORT

A 67-year-old woman was referred to our clinic, presenting an oral mass that had gradually enlarged for 20 years. The lesion caused no pain and it had grown in the last year, causing a facial esthetical deformity and mastication difficulties. Medical history included hysterectomy and double anexectomy. She denied tobacco and alcohol use.

Physical examination showed facial asymmetry (fig. 1). Oral examination revealed a pedicled mass on the left mandibular gingiva, in the edentulous space corresponding to the second molar. It was a 6-8 cm diameter, well demarcated, elastic mass, partially covered by a white membrane. There was mobility and severe displacement of the second premolar, first and third molar and root fragments of the upper teeth. No adenopaties were found on cervical exploration.

Fig. 1. "Visión directa intraoral de tumoración gigante: fibroma cemento-osificante"
"Direct intraoral picture of giant tumour: cemento-ossifying fibroma"

Dental panoramic radiographs showed dental displacement and the mentioned root tips.

Under the probable diagnosis of cemento-ossifiyng fibroma (fig. 2), surgical removal of the lesion was performed with the patient under general anaesthesia. In addition, extraction of the mobile teeth and roots and curettage of the underlying bone was perfomed as well.

Fig. 2. "Deformidad estética facial producida por la lesión"
"Lesion causing facial esthetic deformity"

The recovery was uneventful and no recurrence was detected clinically nor radiologically at 9-month follow-up (fig. 3).

Fig. 3. "Estudio radiológico con ortopantomografía: desplazamiento de 35, 36 y 38 y restos radiculares de 25, 26 y 27"
"Dental panoramic radiograph: dental displacement of 35, 36 and 38 and root tips of 25, 26 and 27"

DISCUSSION

The histology was that of a benign fibro-osseous proliferation composed of bony spicules and espherules admixed with a fibrous stroma. The most distinctive component was the presence of mineralized or calcified "psammomatoid" bodies or ossicles. The ossicles were small with a oval shape without associated osteoblastic rimming. The fibrous stroma was characterized by a spindle cells proliferation that shows a storiform pattern. The lining by a no-keratinized stratified squamous epitelium with overlying ulceration and the superficial parts of the lesion consisted of granulation tissue.The lesion was quite hypocellular with no citologycal atipia and absent of mitotic activity.The histology was consistent with cemento-ossifying fibroma of the oral cavity.

Fibro-osseous lesions of the jaws continue to present problems in diagnosis and classification to clinicians and pathologists, despite the advances in our understanding of this entitie (2,4). The basis on bening fibro-osseus lesions were established by Wladrom and Giasanti in 1973. They made three main categories: fibrous dysplasia, reactive lesions (periapial cemento-osseus dysplasia, focal cemento-osseus dysplasia and florid cemento-osseus dysplasia) and fibro-osseus neoplasms (2).

COF is actually considered as a fibro-osseus dysplasia, included in the group of non odontogenic tumours since the 1992 WHO classification (2,3).

It includes different pathologic entities arising from blastic mesenchimal cells from the periodontal ligament. These cells have potential capability to form bone, cementum and fibrous tissue in combination (1,3).

Most of these tumours occur in the third and fourth decades of life, with a predilection for women (1-5). They are commonly located in dentolous maxillary areas (2), with a higher incidence on premolar-molar mandibular area (70-80%)(1-5), although they might appear in ascending ramus of the mandible (2).

It has a slow clinical progression which conferes a bening nature.

This lesion appears within the bone although in some occasions it involves the gingivae soft tissues (1,3). Bony tumours have the highest incedence in mandible, followed by the maxilla, zygoma and even the ethmoid bone and petromastoid region (1,2).

The clinical evolution of the tumour usually is as follows: Initially asympthomatic, the tumour progressively grows, up to a point in wich its size causes pain, as well as functional alterations and cosmetic deformities (1,3). This has been the evolution of our patient, who presented an enlarged mass producing facial assymetry and displacement of teeth.

Histologicallly it is described as a fibroblastic connective tissue estroma with great cellular variability. The calcified structures consist on rounded or lobulated basophilic masses (cementum-like), trabecuale of osteoid or bone or combination of the two,wich is the most frecuent presentation. In our case, the histology showed bone calcified structures. It is unknown if the cementum-like calcifications are real alveolar cementum because similar calcifications can be found in other fribro-osseus lesions of the skull, placed far from the jaws (2).

Differential diagnosis includes fibrous dysplasia, osteoid ostema, osteoblastoma, low grade osteosarcoma, cemento-blastoma, chronic osteomyelitis and sclerosing osteomyelitis of Garré (1-5). The histologic findings of these lesions are sometimes difficult to distinguish from those seen in COF. In the case of fibrous dysplasia, it is specially difficult for the pathologist to make a diagnosis. Clinical and radiologic information becomes essential (4).

Radiographically, COF may follow different patterns based on the amount of mineralized tissue. It presents as a well-demarcated unilocular lesion, that might have different degrees of opacification inside. It can cause root resorption and teeth displacement (1-5).

Treatment is surgical, consisting on resection of the lesion as well as its osseus floor, by curettage. Because this lesion is low vascularized and well circumscribed, its easily removed from the surrounding bone. This is one of the main differences with fibrous dysplasia (2,3).

Prognosis is excellent and recurrence is rare if it is correctly managed (1-3). We have not found any case of malignant transformation in the literature.

There is a type of COF called juvenile active, that is seen in children and young people ranged between 5 and 15 years old. It involves mainly upper maxilla, having a rapid evolution and a tendency to erose surrounding bone. Histology consists on celulo-vascular stroma with varying degrees of giant cells and poor collagen production. Treatment consists on enucleation and curettage. This type of COF has a higher recurrence rate because of its poorer demarcation, and its higher rate of bone infiltration (2,3,6).

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