Juvenile Aggressive Ossifying Fibroma



CASE REPORT

A 19 year old girl turned up at the dental hospital on January 18,2010, with a painless swelling of about two months’ duration, over the left side cheek. She had been treated for a Cemento-Ossifying Fibroma (COF) about 10 months ago, on March 11, 2009, with surgical excision of the tumor in the left side maxillary antrum region. She had been on regular follow-up ever since and at her last visit, 3 months prior to presentation, no abnormality had been revealed.

On presentation, she had a swelling over her left buccal region. Family and medical history was otherwise normal. Extra-oral examination revealed an obvious facial asymmetry caused by a swelling with normal appearing skin on the left side maxilla. No cervical lymphadenopathy was noted and the mouth opening was normal. Intra oral examination revealed an asymptomatic swelling resulting in buccal and palatal bony expansion and extending antero-posteriorly from the upper left canine region to the upper left first molar region, superiorly to obliterate the sulcus, and inferiorly to the level of the attached gingiva. On palpation the swelling had a bony hard consistency.

Postero-anterior and submento-vertex radiographs of skull were obtained. Postero-anterior radiographic view of the skull showed an ill-defined, predominantly radiopaque mass involving the ipsilateral maxillary antrum and extending from upper left canine region to the upper left molar region.

The clinical picture and the radiological findings were indicative of a recurrent COF.

Surgical management with partial maxillectomy, immediate rehabilitation with a maxillary covering plate, eventually followed by an obturator was planned.

Oral hygiene improvement was done, pre-operatively with a full mouth scaling.

Partial maxillectomy was performed, the lesion was curettaged, cleaned with normal saline, and reconstruction with a maxillary plate was done, all under general anesthesia. Following surgery, the patient recovered uneventfully. The excised lesion was sent for histopathological investigation. The lesion was diagnosed as Juvenile Aggressive Cemento-Ossifying Fibroma-Psammomatoid type (psJACOF). The post-operative surgical pathology report further confirmed that the lesion had been completely excised.

The patient is now under strict and regular follow-up, presently awaits prosthetic rehabilitation with an obturator, and no recurrence has been reported so far.

DISCUSSION

Fibro-osseous lesions of cranio-facial skeleton are relatively rare. Their pathogenesis includes replacement of bony architecture by fibrous tissues, and their subsequent mineralization in various forms such as woven, lamellar bone, and/or cementum. They comprise a vast spectrum of distinct entities with various clinical presentations and microscopic appearances .Most benign fibro-osseous of jaws are slow-growing and symptomless albeit an unusual clinical presentation with aggressive and destructive growth of the lesions can sometimes be encountered in younger individuals, particularly below the age of 15 years. The higher incidence in young adults and children is the characteristic and most striking feature of JOF . Nevertheless, it has reportedly occurred in the older age groups as well. Johnson et al has reported of about JOFs occurring at any age between 3 months and 72 years! On the whole, Juvenile Aggressive Cemento-Osseous Fibroma can justifiably be introduced in a nutshell, as a relatively rare fibro-osseous lesion of the jaws, characterized by the early age of onset, the location of the tumor, the radiological appearance, and the tendency to recur.

A number of classification systems are available for this lesion. Out of these, the classification by Slootweg et al is noteworthy. They have classified JOF into two distinct entities; the JOF-WHO type and the JOF-PO (psammoma-like ossicles) type, taking the usual age of their occurrence as the fundamental criterion. The mean age of occurrence of JOF-WHO type is 11.8 years and that of JOF-PO type is 22.6 years. The most recent classification is by EL-Mofty2.He has identified two distinct categories; trabecular JOF (trJOF) and psammomatoid JOF (psJOF), based on the histopathlogical criteria. Interestingly though, these two categories also have a predilection for specific age groups; the average age of occurrence of trJOF is 81/2-12 years whilst that of psJOF is 16-33 years.

Psammomas

Though JOF can occur anywhere in the skeleton, it is most prevalent in facial bones, particularly the maxilla. psJOF is said to occur mainly in the paranasal sinuses, and trJOF mainly in the maxilla. The mandibular and extracranial involvements are rarer. Sinus involvement is variable, which can be single or multiple. Johnson et al, reviewed 3000 fibro-osseous lesions, and found that a majority of lesions were located in facial bones, and also observed that nearly 90% of them originated from paranasal sinuses.

It is thought that the Juvenile Aggressive Cemento-Ossifying Fibroma arises as a result of the differentiation of mesenchymal cells of the periodontal ligament, pluripotent precursor cells, into fibrous tissue, osteoid, and cementum. On the contrary, Lawton et al , presumes that they perhaps originate from the maldevelopment of the tissue generating the bony septa between the roots of molar teeth. Meanwhile, Pimenta et al , has reported the association of mutation of a new tumor suppressor gene (HRPT2) with ossifying fibroma and has suggested that these lesions could possibly occur as a result of haploinsufficiency of the particular gene.

The usual clinical presentation is an asymptomatic, bony-hard swelling with a varying extent and duration, which depends on the site and aggressiveness of the tumor. However, it does not show the chronic and long-standing natural history of many other fibro-osseous lesions. Facial asymmetry appears due to expansion of the involved bones. Depending on the site, symptoms such as pain, paraesthesia, malocclusion, sinusitis, proptosis, exophthalmos, etc., can also be observed. Persistent growth of the lesions that involve paranasal sinuses may obstruct the normal sinus outflow, and cause subsequent formation of mucoceles. The JOF has also been reported to be associated with other bony lesions such as aneurysmal bone cyst.

JAOF is a discrete mass, well demarcated from the surrounding bone, though not encapsulated9.The cut specimen would show a typically tan-white surface and a rubbery, homogenous mass with a firm-to-gritty consistency.

Radiographically, the internal portions can appear radiolucent, mixed, or radiopaque, depending on the degree of calcification2.They usually appear as a unilobualated or multilobulated lesion in their early stages of development, eventually becoming radiopaque and is surrounded by a uniform radiolucent trimming at later stages.Though not capsulated, the lesion is separated from the adjacent normal bone by a radiopaque border and this feature is particularly useful in differentiating it from fibrous dysplasia10. Root displacement is common, and resorption, though rare, can occur. The lesion can cause expansion as well as perforation.JOF may radiographically resemble other fibro osseous lesions such as fibrous dysplasia and cemento-ossifying fibroma. A “ground glass” appearance on radiographs has been reported. JOF usually has a concentric or centrifugal growth pattern, which can lead to an erroneous clinical diagnosis of Cemento Ossifying Fibroma. Highly aggressive lesions with destructive growth patterns may radiographically mimic osteogenic sarcoma.

The histopathology of the condition is interesting. It consists of a cell-rich fibrous stroma containing bands of cellular osteoid without osteoblastic lining, osteoid strands, and trabeculae of woven bone 2,8,10. A mineralized component composed of many spherical cementum-like bodies surrounded by osteoblastic rimming and a cellular stroma. psJOF is slightly more cellular than trJOF. psJOF consists of psammoma-like ossicles, whereas trJOF consists of trabecular osteoid. Psammoma-like ossicles seen in psJOF resemble cementicles in Cemento-Ossifying Fibroma. Therefore, it has been argued that psJOF is a type of Cemento-Ossifying Fibroma. However, the marked cellularity of JOF is in sheer contrast to the usually stroma-rich appearance of the latter group of lesions.

The microscopy of this particular case revealed spindle and polygonal cells arranged into whorls in a richly cellular stroma. There was evidence of hard tissue formation ranging from calcification through cementum like areas to woven bone. Psammomatoid type calcifications were scattered throughout the lesion. These histopathological features were consistent with those of Juvenile Aggressive Cemento-Ossifying Fibroma (Psammomatoid Type): psJACOF.

Fibro-osseous lesions present a diagnostic dilemma because of their widely overlapping clinical and histopathological findings. A differential diagnosis of fibrous dysplasia, cystic lesions, and osteosarcoma should be considered. Fibrous dysplasia could be ruled out as it typically blends with the normal bone at the margins of the lesion and consists of a less cellular stroma and its osteoid does not exhibit osteoblastic rimming.This particular case presented a well-demarcated lesion from the surrounding bone, and with highly cellular fibrous stroma, and salient osteoblastic rimming histologically, which were suggestive of a JAOF. Benign radiographic appearance, absence of cytological atypia, and absence of infiltration to adjacent tissues ruled out an osteosarcoma.

A thorough combination of clinical, radiological, and histopathological findings can adequately help the clinician to distinguish between JAOF and its counterparts. In this particular case, the combination of clinical features, radiological findings, and histopathological findings along with the past history of swelling and surgical treatment, all confirmed the diagnosis of a JAOF. Nevertheless, it has been suggested that the computer tomography adds value to the diagnosis and confirms the extent of destruction.

This case deserves attention, as it is a recurrence of the lesion after surgical excision of the lesion about 10 months ago. Furthermore, the aggressiveness of the recurred lesion is reflected by the fact that it has shown a clinically notable, rapid growth over a period of less than 3 months! This case supports the earlier literature which recommends the segmental resection of the involved area in order to avoid recurrence . However, several clinical methods are presently being used in the event of management of JAOF. Small lesions can justifiably be treated more conservatively by curettage or enucleation. An open surgical approach, such as transfacial, is ideal for resecting larger and more irregular-shaped tumors that infiltrate sinuses and frontonasal bones. Complete removal of the lesion at the earliest possible stage has been suggested by many authors. Despite the aggressive nature of JAOF, curettage or enucleation of the lesion, until the healthy bony margins are reached, is considered an appropriate form of treatment, particularly so, when the lesion is relatively small.

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