British Journal of Radiology (2005) 78, 175-176
© 2005 British Institute of Radiology
doi: 10.1259/bjr/72810248
The rapidly enlarging chin mass
C Offiah, BSc, FRCS, FRCR and
E Hall, MBChB
Department of Neuroradiology, Hope Hospital, Salford, Manchester, UK
A 25-year-old gentleman of Asian origin presented to the department of oral and maxillofacial surgery with a hard immobile well-defined pea-sized swelling overlying the left and midline body of the mandible. He denied any pain associated with the lesion. He did however remark upon what was interpreted clinically as paraesthesia over the mental region of the chin. The lower right anterior and lateral incisors (4 1 and 4 2) were noted to be mobile. Over the course of 6 weeks the mass enlarged to the size of a golf ball.
Plain film radiography in the form of a panoramic projection (Figure 1
) and right lower periapical projections (Figure 2) were performed at the initial presentation followed by further plain films – panoramic, periapical and occlusal projections – and a CT examination (Figure 3) 6 weeks later. What is the differential diagnosis given the clinical history and radiological appearances?
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Figure 1. Orthopantomograph demonstrating a cystic lesion in the right side of the body of the mandible causing thinning of the cortex and destruction of the lamina dura of the adjacent incisor and canine teeth. There is no evidence of periosteal reaction.
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Figure 2. Lower right periapical projection demonstrating root erosion of the right lower canine tooth by the mandibular mass.
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Figure 3. Post-contrast CT images of the mandibular lesion demonstrating its cystic nature with evidence of cortical break-through and extension into the overlying soft tissues anteriorly but no evidence of periosteal reaction.
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Figure 1
is of the initial panoramic projection obtained at presentation and shows a radiolucent lesion with a distinct narrow sclerotic-appearing margin located in the body of the mandible on the right close to the symphysis menti. There is no distinct septation within the lesion suggesting that it is unilocular and there is no discernible periosteal reaction. The lesion has destroyed the periapical lamina dura of the lower right incisors and canine (4 1, 4 2 and 4 3). Figure 2 is a right lower periapical projection, which confirms the destruction of the lamina dura of these teeth but also demonstrates partial resorption of the root of the lower right canine (4 3). Figure 3 shows axial post-contrast CT image through the mandible, which demonstrate destruction of the anterior cortex of the body of the right side of the mandible but no evidence of periosteal reaction. There is marked soft tissue extension anteriorly centred on the involved region of the mandible. The soft tissue component does not enhance avidly and contains areas of fluid attenuation. The overall radiological appearances are of a non-malignant lesion but the history of rapid growth and facial paraesthesia suggests a diagnosis to the contrary. Surgical excision and histological analysis yielded a diagnosis of juvenile active ossifying fibroma.
Juvenile active ossifying fibroma (JAOF) is rare. It is seen most often in patients between the ages of 5 years and 15 years (60% to 80% of cases) [1]. Cases have however been reported in both older and younger patients [2], some authors suggesting an age range of presentation from 3 months to 72 years [3, 4]. There is no clearly defined racial or sexual predilection. With its diverse histopathology, no clear-cut criteria exist for separating JAOF from the more common forms of ossifying fibroma but its behaviour is markedly different [3]. The tumour can increase rapidly in size in a relatively short time as in our case study. The most common site of involvement for JAOF is the craniofacial skeleton – primarily the maxilla, paranasal sinuses, orbital and frontoethmoid bones [1, 2]. Among the 85% of facial lesions, 90% occur in the paranasal sinuses; most commonly the ethmoid sinuses [3, 4]. The remaining 10% arise from the mandible. Extracranial sites of JAOF account for 4% [4–6].
Clinical manifestations usually begin with swelling of the affected site. The patient may have neurosensory disturbances ranging from pain to paraesthesia in the involved area as in our case. Tumour in the maxilla may produce symptoms of nasal blockage and epiphora [1, 4]. Visual disturbances and blindness from compression of orbital contents and the optic nerve can also occur [4]. Skull base erosion via an involved paranasal sinus can lead to meningitis [4]. A case of stenosis of the supraclinoid portion of the internal carotid artery and associated cerebral ischaemic symptoms due to compression by a JAOF has even been reported [4].
The radiographic appearance of JAOF is of a unilocular, oval or spherical lesion with a distinct osteolytic density delineating it from normal bone. As the lesion enlarges, it can become increasingly radiodense, although still remaining less dense than the adjacent normal bone. Tooth displacement and partial destruction of the roots of teeth is well reported. The main radiological differential diagnoses for JAOF are osteogenic sarcoma, osteoblastoma, fibrous dysplasia and aneurysmal bone cyst (ABC). JAOF is a fibro-osseous tumour and can therefore demonstrate osteogenic elements (absent in our case however) making it difficult to distinguish from osteogenic sarcoma on imaging; the lack of periosteal reaction may be helpful in differentiating this tumour from osteogenic sarcoma however often malignant tumours of the craniofacial bones do not exhibit periosteal reaction. Despite the rapid increase in size that JAOF can demonstrate there is a relative lack of destruction, which is particularly apparent on CT examination. The craniofacial skeleton is a very uncommon site for osteoblastoma (another bone-forming tumour) and ABC. Areas of ABC formation can however sometimes be demonstrated histologically within JAOF [5] complicating differentiation of these two entities. Distinction of JAOF from fibrous dysplasia is more difficult but fibrous dysplasia tends to have relatively indistinct borders blending into surrounding bone compared with the typically well-defined demarcation from surrounding, healthy bone demonstrated by JAOF. In addition, root resorption is not a common feature of fibrous dysplasia in contrast to JAOF [3–6].
The painless rapid growth demonstrated by this juvenile form of ossifying fibroma and the tendency to a locally aggressive growth pattern has justified the prefix "active" or "aggressive" in reference to these tumours. Histologically, JAOF shows some variance but typical features include a highly cellular stroma containing calcified components, which is usually fibroblastic and relatively avascular accounting for the lack of enhancement on imaging; woven and interconnecting lamellar bone with numerous eccentric rims of osteoblasts are also demonstrated. The highly cellular nature of the stroma reflects the aggressive nature of these tumours [3, 5, 6].
Complete surgical excision is necessary to obviate local recurrence. This can usually be achieved by local excision and curettage [2, 5]. Adjunctive treatment is not required. Malignant transformation has never been recorded.
JAOF, although a rare lesion, is worthy of inclusion in the radiological differential diagnosis of a rapidly expanding lesion affecting the craniofacial skeleton of an adolescent or young adult. Differentiation from other benign and malignant neoplasms is important in the correct therapeutic management of this tumour.
Received for publication May 14, 2004.
Revision received November 5, 2004.
Accepted for publication November 25, 2004.
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References
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- Wiedenfeld KR, Neville BW, Hutchins AR, Bell RA, Brock TR. Juvenile ossifying fibroma of the maxilla in a 6-year-old male: case report. Pediatr Den 1995;17:365–8.
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