Giant ossifying fibroma of the maxilla: an unusually aggressive presentation in a 21-year-old woman

Abstract

We present a rare case of a huge aggressive ossifying fibroma of the maxilla in a 21-year-old female patient with involvement of the maxillary antrum, nasal cavity, orbit and the ethmoid sinus with a unique radiologic appearance for documentation.

Background

Ossifying fibroma (OF) is a rare benign fibro-osseous lesion of the skull and facial bones which when grows rapidly and attains huge size, can mimic a malignant tumour.¹ It comprises of two components: the fibrous tissue stroma and the bone exhibiting different levels of maturation. The mandible is predominantly affected, especially the molar-ramus region with swelling and facial asymmetry being the most common clinical findings.² Although the age of incidence is in the third and fourth decade, younger individuals may also be affected. Radiologic appearance is mostly unilocular but with varying degrees of calcifications. The lesion is initially radiolucent and gradually shows calcifications as it matures.³ Although, clinical, radiological and histological characteristics of OFs may not always show aggressive behaviour, it is certainly accentuated in some cases which are locally invasive and destructive.

Case presentation

A 21-year-old female patient reported with a swelling in the left side of the face for 5 months. History revealed that the swelling was small initially and the patient underwent surgical excision following which the swelling reappeared and started growing rapidly. The patients’ medical, dental, personal and family histories were unremarkable.

On physical examination, a single diffuse swelling was seen on the left side of the face, measuring about 3×5 cm in size, ovoid in shape with ill-defined borders with mild tenderness elicited on palpation (figure 1A). Intraorally, a diffuse swelling was seen on the left side of the maxilla and crossing the midline of the palate, irregular in shape, of the oral mucosal colour, measuring about 3×5 cm in size, with a surface ulceration and sanguineous discharge (figure 1B). The swelling was warm to touch with moderate tenderness on palpation, irregularly shaped having multiple lobulated growths, diffuse edges with tenderness in the surrounding bone. The base was sessile, the swelling was firm in consistency and attached to the underlying bone.

Figure 1.

(A) Diffuse swelling seen on the left side of the face. (B) Diffuse swelling seen on the left side of the maxilla and palate crossing the midline with lobulated growths and ulceration, irregular in shape, measuring 3×5 cm in size, with a serosanguinous discharge.

Due to the rapid growth, surface ulceration and enormous size, the lesion was considered a malignant soft-tissue neoplasm, the differential diagnosis included non-Hodgkin’s lymphoma, fibrosarcoma, osteosarcoma and malignant salivary gland neoplasms like mucoepidermoid carcinoma, adenocarcinoma, adenoid cystic carcinoma and adenocarcinoma.

Investigations

Contrast-enhanced CT

Radiologic evaluation with contrast-enhanced CT scan revealed an expansile bony lesion with soft-tissue involvement of size 8×7×6 cm arising from the left maxilla showing varying degree of calcified material (figure 2A) involving the maxillary sinus, left nasal cavity, hard palate, extra conal and conal involvement of left orbit and showing extension into left ethmoid sinuses. Left orbital floor erosion with rim of enhancing soft-tissue in extra conal space (figure 2B). Three-dimentional reformatted images showed extensive destruction of the maxilla extending into the orbit and the calcifications were giving the appearance of a sun burst appearance akin to that seen in osteosarcoma and chondrosarcoma confounding the radiologists.

Figure 2.

(A) CECT coronal section shows expansile bony lesion arising from the left maxilla showing varying degree of calcified material with a ‘sun burst like appearance’ involving the maxillary sinus, left nasal cavity, hard palate, extra conal and conal involvement of left orbit and orbital floor erosion with rim of enhancing soft-tissue extending into the ethmoid sinuses. (B) 3D reformatted images showed extensive destruction of the maxilla extending into the orbit. 3D, three dimensions; CECT, contrast-enhanced CT.

Incisional biopsy

An incisional biopsy was performed under local anaesthesia and histopathological evaluation using H&E staining revealed fibro-collagenous stroma with ossicles of various shapes having basophilic centre with peripheral eosinophilic osteoid rims. Peripheral fibroblasts rimming is evident in multiple ossicles. Myxomatous foci and pseudocystic changes were also noticed. The histopathological features were compatible with OF (figure 3).

Figure 3.

Histopathological features are compatible to ossifying fibroma (original magnification ×10). Insert showing ossicles with basophilic centres surrounded by eosinophilic osteoid rims. (Original magnification ×40).

Treatment

The patient was advised for excision and reconstruction with a multidisciplinary team comprising of maxillofacial surgeons, otorhinolaryngologists and neurosurgeons but the patient deferred surgery due to financial constraints.

Outcome and follow-up

The patient regularly came for monthly check-ups but was subsequently lost to follow-up in 3 months.

Discussion

OF is an uncommon non-odontogenic fibro-osseous neoplasm which arises from the blast cells of the periodontal ligament and has the capability to produce fibrous tissue, osseous tissue, cementum or even a combination of bone, cementum and fibrous tissue.¹ Although benign, rarely OF may exhibit extensive growth specially in younger adults below 25 often attaining an enormous size as seen in the present case.

Since the origin is from the periodontal ligament, the lesion is usually associated with the tooth bearing areas. Thompson and Bernier had theorised that chronic infection leading to inflammation and fibrosis of the periapical region stimulates the periodontal ligament. Also following trauma, like tooth extraction, the residual periodontal tissue adhering to the wall of the alveolar socket may give rise to the origin of an OF.² The clinical features are similar to other fibro-osseous lesions, like swelling causing facial asymmetry, displacement of teeth, expansion of the alveolus and rarely pain or paraesthesia.¹

The radiologic appearance is variable depending on the degree of mineralisation in the lesion and varies from unilocular or multilocular radiolucent lesion to a mixed radiolucent- radiopaque appearance may be seen.³ It is well encapsulated, hence is associated with a well-defined radiolucent line peripherally. On CT images, OF appears as a heterodense mass with numerous internal foci of punctate calcifications and enhancing soft-tissue.⁴

Histological appearance generally presents hypercellularity in fibrous stroma with small spherules or ossicles.⁵ The stroma varies from being loose and fibroblastic to intensely cellular with minimum intervening collagen. The mineralised material may be curvilinear or spherical with some sparsely distributed ossicles and multiple deeply basophilic concentric lamellar structures and needle like irregular calcifications in a hyalinised background.⁵ No cellular atypia or mitotic figures are seen even in the most aggressive and bizarre lesions which clinically and radiologically may appear as malignancy like the present case.

Treatment is also variable ranging from conservative enucleation/curettage in smaller lesions to radical surgery in lesions with multiple bone involvement. Larger lesions must be treated with en bloc resection to prevent recurrences given the fact that recurrent lesions are generally more aggressive besides emphasising the importance of a long-term follow-up.^{3 4}

OF, rarely occurs in the maxilla, though benign can have a high potential of growth and be associated with bone destruction, local invasion especially with recurrence.^{2 5} The recurrence rate is low at 14% but huge expansile lesions are difficult to treat conservatively and hence require radical excision.⁴ It can clinically and even radiologically mimic malignancy. Hence it is imperative the lesion is diagnosed early, treated with radical excision to prevent recurrence and followed up for long term.

Learning points.

• Ossifying fibroma is a benign fibro-osseous neoplasm commonly affecting the jaw bones, especially the mandible.

• It clinically appears as a slow growing, well-circumscribed jaw swelling, with a mixed radiopaque-radiolucent appearance on radiographs.

• This can be aggressive, often recurring after conservative surgical procedures, growing to bizarre sizes requiring extensive surgery.

Ethics statements

Patient consent for publication

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