Cemento-ossifying fibroma (COF) is a nonneoplastic but locally destructive tumor of unknown etiology consisting of fibrous tissue and varying amounts of mineralized material. It is rarely described as a cause of ophthalmic symptoms and signs. We report a case of COF of the maxilla in a young patient who presented with proptosis. With a review of the literature we highlight the diagnostic confusion that remains about this fibro-osseus lesion and discuss its management.
An 8-year-old boy presented with epiphora and progressive painless proptosis of the right eye for more than 4 weeks. He had been assessed in the ENT department 2 years previously with recurrent sore throats, mouth breaming, and snoring. Facial roentgenograph had shown an opaque right maxillary antrum. He had undergone bilateral antral washouts diat were clear and adeno-tonsillectomy. Nasal congestion ana rhinorrhea persisted. Eighteen months later, rhinitis, hypertrophied inferior turbinates, and deviation of die nasal septum to die left were noted. He was offered a conservative operation.
Figure 1 : Preoperative appearance showing right proptosis with upward displacement of the globe, fullness of the maxilla, and mild facial asymmetry.
Clinical examination revealed a 5 mm right proptosis with upward displacement of the globe, fullness of the maxilla, and nuld facial asymmetry (Figure 1). Best corrected visual acuity was 20/20 in the right and left eyes. Color vision, pupil reactions, eye movements, and stereoacuity were normal. On fundoscopy the right optic disc was mildly swollen and the left was normal.
Magnetic resonance imaging (MRI) scan demonstrated a well-defined, multiloculated lesion affecting the right maxillary antrum, displacing the globe anteriorly. Computed tomography (CT) scan revealed a 5 cm expansive lesion of soft tissue density with diickening of its margins and some internal calcification (Figure 2). The anterior and posterolateral walls of the maxillary antrum were bowed outwards with signs of destruction of the medial wall. Superiorly, the lesion extended into the ethmoid region wirb bowing and attenuation of the medial orbital wall. Posteriorly, it extended into the nasopharynx.
Figure 2: Axial computed tomography scanning (bony windows) shows the right maxillary antrum occupied by a lesion of softtissue density with thickening of its margins and some internal calcification. The lesion is deviating the nasal septum to the left.
An incisional biopsy of a large distensible mass in the nasal cavity revealed macroscopically a 14 mm irregular piece of pinkish-grey tissue of elasticrubbery consistency with a uniformly compact appearance. Microscopic examination showed a large and monotonous sheet of slightly elongated and mostly uniform tumor cells of dense arrangement with occasional irregular bundles, and trabecules or abortive whorl-like formations. Between the tumor cells throughout the entire section were numerous, well demarcated, mostly round or oval, intensely eosinophilic, acellular, homogenous calcified structures (spheriscules) with only focal evidence of osteoid formation. These appearances were diagnostic of cemento-ossifying fibroma (Figure 3).
This was considered a locally aggressive and destructive tumor requiring complete excision. Preoperative CT scanning two months later confirmed a wide defect in the medial wall of the maxillary sinus with a 5 ? 5 ? 5 cm tumor filling the right side of the nasal space and extending superiorly to the skull base as far as the cribriform plate.
It was believed diat surgery to remove the tumor in total under direct vision from above, should involve bodi an anterior approach by rotating the medial portion of the orbit outward, and a transcranial approach to protect the eye. Using a bicoronal flap and midfacial split, access was achieved via frontal craniotomy, supraorbital bar, and right en-bloc superior-medial-inferior orbitotomy. The tumor extended from the right maxillary alveolus, eroding through the right orbital floor and across the midline, to the back of the maxilla into the posterior ethmoid sinuses near the optic nerve. It was shelled out in one piece and resected with the maxilla. The floor and medial orbital walls were reconstructed using split calvarial bone graft. The immediate postoperative period was uneventful.
Figure 3: Typical microscopic appearance of the tumor: sheets of uniform and elongated mesenchymal cells creating abortive whorl-like structures focally (A) and showing numerous calcified spheriscules with minimal osteoid only (B) (original magnification x 40, H&E).
The operative resection was a large, slighdy lobulated, firm to rubbery, nonencapsulated, pyramidshaped tumor mass, weighing 72 grams and measuring? ? 5 x 4 cm. Microscopic investigation confirmed identical histomorphological appearances described earlier in the biopsy sample, consisting bodi of elongated oval mesenchymal cells and numerous calcified spherical structures. The tumor only focally invaded the sinus mucosa, but extensively destroyed and segmentally replaced the maxillary bone.
Six months following surgery, 2 endonasal dacryocystorhinostomies were required for persistent epiphora and mucocoele formation. Further reconstruction of the maxilla and possibly implants for fitting of dentures are planned. The resection was believed complete and has maintained good cosmesis (Figure 4). The patient remains under regular review with no evidence of tumor recurrence or epiphora at three-year follow up.
"Droplets of cementum" (cementides) are classically described in the diagnosis of COF on histological examination.1 Aldiough this implies a tumor of odontogenic origin, similar droplets of a cementum-like material are found in some fibro-osseus tumors of the extragnatbic craniofacial skeleton and long bones. Derivation from odontogenic tissue in these sites is unlikely.2 Cementum itself is widely accepted to be a form of bone, and cementicles have never been conclusively differentiated from "osteiod spherules" (ossicles) by either histochemical staining or polarized light.' The WHO International Classification of Tumors categorizes COF as a neoplasm related to bone rather than the odontogenic apparatus. The term COF is often used to simply reflect the anatomical location of the tumor to the jaw rather than any histological origin.3
COF of rhe jaws and ossifying fibromas in the paraorbital region are clinically well described, each sharing similarities and disparities with our case.3'9
Three large series on COF report an average tumor diameter of 3.8 cm and a radiological appearance similar to our case. However, lesions normally occur in the 4th decade with a female preponderance and predominantly involving the mandible.4·5·7
Conversely, psammomatoid ossifying fibromas (POF) are diagnosed at an average age of 18 years with symptoms for 4.6 years and equal sex incidence. Lesions are on average 5.3 cm in diameter, seen radiographicaUy as a well-circumscribed tumor with variable density and bony destruction. They are located in the superior orbit, ethmoid, and sphenoid sinuses where tfrey can often cause proptosis.3·8·9
Johnson10 described an entity called juvenile active ossifying fibroma (JAOF). The average age of onset was 12 years of age with 20% of lesions originating in the maxillary sinus and 10% in the mandible. Most lesions were 2-5 cm but "rarely attained giant size." However, cyst formation was common.
Both the terminological confusion and varied clinical descriptions make it difficult to identify where our case fits into the previous literature. We were able to find six cases for comparison in which a giant cementifying/ossifying fibroma of the maxilla had involved the orbit in children.11*15
The average age of the patients was 10.6 years with an equal sex predilection. Symptoms and signs of painless, unilateral facial swelling and asymmetry, nasal congestion, epiphora and ultimately progressive proptosis, elevation of the globe, diplopia, and visual loss are reported. Onset of symptoms to diagnosis, where recorded, has varied from 2 mondis to 2 years. Though clinical suspicion will aid early diagnosis, delay may pardy be explained by the expansion of the maxillary sinuses at this age, masking growth of die tumor.10
Figure 4: Postoperative appearance at 2.5-year follow up.
Orbital involvement will result from giant tumors. Although increased aggression may correlate with the juvenile age of onset, large maxillary lesions with an orbital presentation have been described in adults. "^18 A delay in diagnosis may allow massive sizes to be attained.13 Sudden expansion following trauma or surgical interference is reported.18,19 In the case presented, the long history of nasal symptoms, signs, and initial sinus reoentgenograph are pertinent dues to the underlying abnormality.
A well defined, variably radio-opaque lesion with bony destruction or expansion is found on imaging. The radiographic and histological appearances are important in differentiating this tumor from a number of other non-neoplastic bone lesions such as osteoblastoma (osteoma), giant cementoma, central giant cell granuloma, and aneurysmal bone cyst. Fibrous dysplasia is often quoted as an important differential diagnosis aldiough die histopadiological features may not be dissimilar.2,10 Mucoceles cause bony expansion but often arise from the frontal or ethmoid sinuses. Clinically and histologically POF has been confused with a meningioma.3 A shorter, painful history should alert one to an osteosarcoma or eosinophilic granuloma.
In a series of children with COF, an average of 2.5 operations were required after piecemeal excision or curettage." Recurrence is also reported in 38% of POF and 30% of JAOF, the majority of which were removed in piecemeal fashion.3,10 Therefore, it was decided to remove the tumor en bloc.
The demographics of our cases would seem to differ from COF as described in the literature, sharing more similarities with JAOF and POF of the orbit. The anatomical location of the tumor and its relation to the orbit remains an important clinical marker, defining the characteristics of presentation and multidisciplinary management that are required. To aid future case comparison, terminology should be streamlined to reflect the rather closely related nature of these fibro-osseous lesions.
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