Juvenile Ossifying Fibroma (JOF)

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The age of this patient is within the age range in which this neoplasm is likely to occur, and the radiographic findings are also suggestive of this condition. The location, however, is not typical of juvenile ossifying fibroma. The histology is not supportive of this condition.

Juvenile ossifying fibroma (JOF) is a rare benign but aggressively behaving neoplasm of fibro-osseous origin that affects the jaws and craniofacial bones. It is an aggressive variant of a more common benign jaw bone neoplasm known as central ossifying fibroma (COF) occurring more commonly in the posterior mandible, inferior to the premolar and molar teeth with a distinct predilection for occurrence in females at a 5:1 ratio around 35 years of age. Central ossifying fibroma grows in a centrifugal manner; it can expand the bone bucally and lingually as well as superior and inferior aspects. It is radiographically diagnostic in that it is well demarcated with a corticated border and the central portion of the neoplasm ranges from radiolucent (early stages) to mature radiopacity (late stages) with a connective tissue capsule radiographically identified as a radiolucent rim.

Juvenile ossifying fibroma of the jaws, although a variant of COF, is distinct in several respects: its behavior, the location, the age of the patient and histologic features. As mentioned previously, this neoplasm is locally aggressive. It can simulate the behavior of a low-grade sarcoma with its tendency for fast growth, invading the surrounding tissue and destroying bone, displacing teeth and, at times, causing exophthalmos and diplopia. Tenderness and mild pain is also described, but not paresthesia, as was the case in this patient. It is more common in the maxilla and the craniofacial bones and sinuses.

Two histologic variants of JOF are described: trabecular and psamammatoid types. Trabecular JOF is histologically characterized by cellular connective tissue stroma interspersed with strands of trabeculae young bone with prominent osteoblastic rimming. Psammomatoid JOF is characterized by cellular connective tissue stroma with small and uniform cementum-like hard tissue resembling Psammoma bodies. Trabecular JOF occurs more commonly in the jaw bones; it is about twice as common in the maxilla as in the mandible. The pasammamatoid type occurs more commonly in the paranasal sinuses. Both types are suggested to be of equal gender predilection or slightly more common in males. Psamammatoid JOF occurs more commonly in the paranasal sinuses (about 70% of cases) with 20% of cases occurring in the maxilla and 10% in the mandible. Generally, JOF is more common in children under 15 years of age; trabecular JOF tends to occur in younger patients with a range of 8.5-12 years while psamammatoid JOF affects older children with a mean age of 20-22. This patient's case was more trabecular in type mixed with areas of psammamatoid morphology.

Radiographically, JOF ranges from a well-demarcated radiolucency, as is the case in this patient, to mixed radiolucent/radiopaque or predominantly radiopaque depending on the stage of the disease and degree of calcification. It can be unilocular or multilocular, well defined or ill defined. Both histological types have a high recurrence rate ranging from 30 to 56%. Treatment ranges from thorough curettage to resection to curettage with subcutaneous interferon injections. The latter has been reported to be effective in inhibiting tumor growth and recurrence.