Cemento-Ossifying Fibroma
Synonym / Acronym
Ossifying fibroma, cementifying fibroma / COF
Definition
Cemento-ossifying fibroma is a fibro-osseous lesion that has benign neoplastic behavior. The lesion is composed histologically of varying amount of highly cellular, fibrocellular tissue and immature hard tissues (osteoid, bone, and cementum). Ossifying and cementifying fibroma represent histologic variants of the same lesion depending whether bone (in ossifying fibroma) or cementum (in cementifying fibroma) was the main calcified product. Juvenile ossifying fibroma represents an aggressive form of COF usually occurring during first two decades of life.
Clinical Features
Characteristics of COF are more of a benign tumor rather than a fibro-osseous process and sometimes COF can have aggressive behavior. COF can occur at any age but usually between second and fourth decades of life. Females are affected much more than males. Cemento-ossifying fibromas are generally asymptomatic and they can cause facial asymmetry. They are often detected during routine dental examination.
Radiographic Features
The radiographic appearance of the lesion can vary greatly depending on its stage of development. At early stages, the lesion is totally radiolucent. Intermediate stage of the lesion exhibit mixed radiolucent and radiopaque density depending on the amount of the calcified material. It can appear as wispy (similar to the pattern seen on CGCG), or ground glass (similar to the pattern seen on fibrous dysplasia), cotton wool, or flocculent (similar to large snowflakes). Cementum like structures “cementicles” (similar to those seen on cemental dysplasia) can also be present. Presence of septa can give multilocular appearance. The borders of the lesion are well-defined and there is a radiolucent rim of fibrous capsule separates the lesion from the surrounding bone. COF occurs usually in the posterior mandible between premolars and premolars area and above the mandibular canal. If it occurs in the maxilla, it is most likely to be found in the canine fossa and the zygomatic arch area. COF can displace teeth but rarely cause root resorption. Lamina dura is missing. The lesion will displace the mandibular canal and floor of maxillary sinus. Cemento-ossifying fibroma has propensity for outward expansion in all direction which expands cortical plates. The plates are expanded and thinned but never perforated.
Differential Diagnosis
We can include in our differential, the lesions that have mixed radiolucent-radiopaque appearance. It may be impossible to differentiate COF from fibrous dysplasia. COF has a well-defined margins and one of the key features that differentiate COF from fibrous dysplasia is the presence of a radiolucent fibrous tissue capsule around the lesion; while fibrous dysplasia tends to blend with surrounding normal bone. Both COF and fibrous can displace teeth. The expansion in COF is usually around the epicenter while fibrous dysplasia can alter the outer shape of the cortical bone to a slight degree. Differentiating the lesion in the maxillary sinus is much more difficult. COF expands into the maxillary sinus while fibrous dysplasia displaces the sinus lateral wall towards the sinus. Determining whether the lesion is ossifying fibroma or fibrous dysplasia can greatly affect the treatment plan for the patient as with ossifying fibroma the treatment is resection while with fibrous dysplasia it usually observation. Differentiation COF from PCD is usually difficult especially in cases where there is a single large lesion. It is more common to see a simple bone cyst associated with cemental dysplasia. Usually cemental dysplasia has sclerotic borders. Other mixed lesions can be included in the differential like COC, CEOT (Pindborg tumor), and AOT.
Treatment
Surgical enucleation or resection is carried out. Cone Bean CT can be used to evaluate the location and extension of the lesion.
Case Reports
HISTORY: A 47-year-old female patient was referred for Cone Beam CT scan for evaluation of left maxilla regarding expansile lesion.
FINDINGS: There is a mixed density lesion associated with the left side anterior maxilla. There is significant expansion and thinning of the cortical boundaries. The lesion is close to the nasal fossa and the medial part of the lesion comes in close proximity to the nasal septum in the midline of the face. The lesion extends posteriorly to more than half the length of the maxilla. The lesion has replaced the anterior part of the maxillary sinus and the inferior nasal concha. The superior border of the lesion is located in close proximity to the medial aspect of the inferior orbital rim. The dimensions of the lesion approximately are 46 mm H (super-inferiorly), 35 mm W (medio-laterally) and 42 mm L (postero-anteriorly). The lesion boundaries are corticated in most parts. There are multiple calcified flecks represent calcifications in the lesion with the largest ones located in the medial aspect of the lesion.
Another lesion is located in the anterior mandible. The lesion is mostly radiolucent except for a calcified mass associated with tooth #26. Teeth #24, 25 are missing. The boundaries of the lesion are moderately to ill-defined. The lower incisor teeth appear to be floating.
IMPRESSIONS: The radiographic signs are suggestive of a benign lesion. They are most consistent with cemento-ossifying fibroma. The signs of the lesion in the mandible are consistent with aggressive periodontitis and the calcified material represents calculus. However, there a relationship with the lesion in the maxilla or a malignancy cannot be excluded based on the current radiographic examination. Clinical follow-up is recommended.
