IntroductionCemento-ossifying fibroma (COF), as per the World Health Organization’s (WHO) 2022 classification of head and neck tumours, is a well-demarcated neoplasm which consists of fibrous tissue containing varying amounts of mineralised material resembling bone and/or cementum (1). It is a benign fibro-osseous lesion, and is derived from the multipotential mesenchymal blast cells of the periodontal ligament (2).COF was already defined as a benign mesenchymal odontogenic tumour in the 2017 WHO classification. However, it was described under the category of fibro-osseous lesions (3), but is now an integral part of the benign mesenchymal odontogenic tumours in the 2022 classification, completely isolated from the non-odontogenic juvenile trabecular (JTOF) and psammomatoid types (POF) (1).COFs occur mostly in between the second and fourth decades of life with a definitive female predilection in the ratio of 4:1 (4). However, they may be present in children and adolescents, as well as in older adults (5,6). The mandible – preferentially in the molar region – is more involved than the maxilla (7), albeit other cranial and facial bones such as the frontal, periorbital, sphenoid, ethmoid and temporal bones are also affected (8). The tumour is termed central COF when lesions are located intraosseously, whereas peripheral COF refers to extraosseous lesions, or those appearing on the outer soft tissue (9). The tumour is well demarcated by a teeny sclerotic shell of bone. Unpredictably, it may either show a slow growth or appear to be locally aggressive with cortical damage and involvement of several nearby anatomical structures (10).Histologically, the neoplasm is composed of a proliferating fibrous tissue and osseous particles containing bony strands and cementum-like material (5). This lesion is thought to occur in reaction to low-grade irritations such as trauma, calculus, plaque, masticatory forces, ill-fitting dentures and poor-quality restorations (11).Clinically, OF presents as a spherical or ovoid, generally slow-growing, painless and expansive jaw bone mass that may displace the roots of adjacent teeth, and occasionally causes facial deformity and/or functional discomfort (12). Definitive diagnosis requires correlation of clinical, radiographic, and histopathological findings (13). The treatment consists of surgical excision with enlarged resection depending on the size and location of the lesion (10,14).For an optimal management of COF, an accurate diagnosis is necessary. Clinical presentation is not unique, and the radiological patterns depend on the degree of mineralisation of the tumour. The clinician is then confronted by the overlapping patterns of the broad spectrum of fibro-osseous tumours, and the presence of unusual patterns makes the diagnosis even more challenging. We present a rare case of COF in a 22-year-old female patient in the lateral maxilla, which is an unusual site of occurrence.Case reportA 22-year-old female patient was referred to the Department of Oral and Maxillofacial Surgery with a painless swelling in the upper right region of the jawbone since 10 years. The swelling sprouted as a small painless nodule when the patient was 12, and grew with time. As the swelling was increasing, only the vision was shielded, but the deglutition and breathing were not affected. Mastication on the right side and speech were also affected. No pain, fever, or any comorbidity were reported. There was no history of previous similar swelling, toothache, numbness, trauma, surgery, or radiotherapy. Although the patient was from a low socio-economic status, her parents and siblings were all well. There was no similar swelling in the family.The patient’s general condition was otherwise good with fair nutritional status. Extraoral examination showed a bulky, dome-shaped, and well-defined swelling extending over the right hemi-maxilla with a frontward expansion causing facial disfigurement. The dome of the swelling was budding and ulcerated. The palpation of the swelling revealed a bony hard consistency, with no tenderness elicited. The mass was immobile on mobilisation and measured approximately 40 cm × 12 cm in size (figure 1). On intraoral examination, all the teeth of the right hemi-maxilla were buried under the swelling.There was no palpable lymphadenopathy. Neurological examination, as well as respiratory, digestive, and urogenital explorations did not reveal any abnormality.A maxillofacial computed tomography (CT) was performed, and revealed a well-circumscribed exuberant mass in the right facial region, spanning from the right palatal and maxillary bones and extending into the right malar bone. Detailedly, an osteoforming excrescence with a regular margin, and a mixed density content made of soft tissue and diffuse scattered calcified foci, with teeth 21 to 28 engulfed in the mass (figure 2). Also, CT image showed a mass effect of the tumour causing left deviation of the nasal septum, with a narrowed osteo-meatal system, yet preserving its anatomical structure (figure 3).A provisional diagnosis of osteoblastoma was recorded, with fibrous dysplasia and ossifying fibroma being considered in the differential diagnosis.An excisional biopsy (16 × 10 cm) of the tumour was performed, and the histopathological examination revealed a well-circumscribed fibrous tissue containing dispersed foci of calcification. The mass harboured dense bundles of fibrocollagenous connective tissue in a cellular stroma (figure 4). The matrix was formed by interconnected trabeculae of mature lamellar bone with fibroblastic rimming (figure 5). No atypical cells nor mitosis were observed, and the lesion also showed an ulcerated stratified squamous epithelium. On the basis of histopathological findings, and correlating them with clinical and radiological features, a final diagnosis of (peripheral) cemento-ossifying fibroma was established, excluding JTOF and POF subtypes.As management, a surgical resection of the tumour was performed, followed by curettage. Postoperative period was uneventful, and a clinical follow-up plan was established for review after 3 months, 6 months, and 1 year after surgery.
