Annals of Diagnostic Pathology 17 (2013) 198–203

Contents lists available at SciVerse ScienceDirect

Annals of Diagnostic Pathology

Radiologic-Pathologic Correlations

Clinicopathologic and radiologic correlation of ossifying fibroma and juvenileossifying fibroma—an institutional study of 22 cases☆

Aadithya B. Urs MDS, Priya Kumar MDS⁎, Shelly Arora MDS, Jeyaseelan Augustine MDSDepartment of Oral and Maxillofacial Pathology, Maulana Azad Institute of Dental Sciences, BSZ Marg, New Delhi—110002, India

☆ Conflict of Interest: None declared.⁎ Corresponding author. Department of Oral and Ma

Azad Institute of Dental Sciences, Bahadur Shah Zafar MTel.: +91 9654700985.

E-mail address: drpri_kumar@yahoo.com (P. Kumar

1092-9134/$ – see front matter © 2013 Elsevier Inc. Alhttp://dx.doi.org/10.1016/j.anndiagpath.2012.06.003

a b s t r a c t

a r t i c l e i n f o

Keywords:

Aneurysmal bone cystHistopathologyJuvenile ossifying fibromaOssifying fibroma

To analyze the clinical, radiographic, and histopathologic features of ossifying fibroma (OF) and juvenile OF(JOF), an archival study of 17 cases of OF and 5 cases of JOF reported over a period of 4.5 years was undertakento analyze the aforementioned features. Age incidence of OF varied from 8 to 53 years, and JOF was seen in acomparatively younger age of 8 to 28 years. Both tumors were almost equally distributed between men andwomen. Thirteen cases of OF were found to occur in posterior mandible, whereas JOF was predominant in theanterior maxilla. Radiographically, OF varied from completely radiolucent (n = 7), mixed (n = 5), tocompletely radiopaque (n = 5), whereas JOF was predominantly radiolucent. Microscopically, stroma in OFvaried from fibrous to highly cellular with overlap between various types of calcification. Juvenile OF showedhighly cellular stroma and 2 distinct patterns of mineralization-psammomatoid and trabecular with osteoidseams. The origin of OF and JOF seems to be distinct from each other with OF arising from periodontalligament and JOF arising from precursor myxoid tissue of paranasal sinuses.

xillofacial Pathology, Maulanaarg, New Delhi—110002, India.

).

l rights reserved.

© 2013 Elsevier Inc. All rights reserved.

1. Introduction

The term ossifying fibroma (OF) has been used since 1927. TheWorld Health Organization (WHO) in 1971 classified cementumcontaining lesions into fibrous dysplasia, OF, cementifying fibroma,and cemento OF. However, the term cemento OF was reduced to OF in2005 in the new WHO classification [1].

Ossifying fibroma of the jaws are well-circumscribed generallyslow-growing lesions that enlarge in an expansile manner [2]. Thetumor is defined as a demarcated and occasionally encapsulatedlesion consisting of fibrous tissue containing variable amounts ofmineralized material resembling bone and/or cementum [3]. Theseare most commonly seen in the third and fourth decades of life. Theyare largely restricted to tooth-bearing areas of the jaws, althoughposterior mandibular lesions may extend upwards into the ascendingramus for some distance. Of these lesions, 70% to 80% occur in themandible, most often in the premolar-molar region with a definitefemale predilection [3].

Juvenile OF (JOF) is a large asymptomatic tumor of aggressiveappearance because of the bone destruction it produces. The lesion isnot encapsulated, although it is well demarcated from the surround-ing bone [4]. The 2 variants of JOF, namely, psammomatoid JOF

(PsJOF) and trabecular JOF (TrJOF), differ entirely in their clinical andhistopathologic presentation. The average age of occurrence of TrJOFis considerably younger than PsJOF with average being 8 1/2 to 12years as compared with 16- to 33-year range in case of PsJOF.Distribution is biased toward men. With respect to site, PsJOF occursoverwhelmingly in the sinonasal and orbital bones of the skull,whereas TrJOF is predominantly a gnathic lesion affecting jaws with apredilection for the maxilla [5].

The present study was undertaken to analyze the clinical,radiographic, and histopathologic features of the reported cases ofOF and JOF. An attemptwas alsomade to elucidate the pathogenesis ofthese lesions by correlating the clinicopathologic features.

2. Materials and method

Cases that were histopathologically diagnosed as OF and JOF wereretrieved from the archives of Department Of Oral Pathology, MaulanaAzad Institute of Dental Sciences, India, from January 2007 to June2011. Clinical and radiographic findings were available for all cases.Careful investigation was carried out to avoid inclusion of lesions suchas fibrous dysplasia, focal and florid cemento osseous dysplasias,syndrome-associated lesions, and multifocal lesions in the series.Special emphasis was taken for choosing cases of JOF as per thefollowing criteria [6]:

a) the lesion showed a morphology consistent with the WHOdefinition of JOF, having a fibroblastic stroma containing strandsof cellular osteoid; or

199A.B. Urs et al. / Annals of Diagnostic Pathology 17 (2013) 198–203

b) the lesion demonstrated psammoma-like ossicles embedded in aspindle cell stroma [7].

Accordingly, 22 cases were selected, which included 17cases of OFand 5 cases of JOF. All the cases selected were analyzed with respect toage, sex, site of occurrence, radiographic presentation, and histopa-thology. Histologic sections of the excisional tissue were studied by 4pathologists, and the lesions were analyzed with respect to thefollowing features:

1) nature of supporting stromal tissue:a) highly cellular;b) cellular; orc) fibrous

2) nature of bony trabeculae:a) mature bone;b) immature bone; orc) osteoid seams

3) nature of calcification:a) cementicles;b) ossicles; orc) psammoma bodies

4) secondary changes:a) association with other lesions, for example, aneurysmal bone

cyst (ABC);b) presence of myxoid change/hemorrhage/necrosis/

inflammation.

3. Results

Clinical data analyzed revealed that the age incidence for OF variedfrom 8 to 53 years with a peak occurrence in third decade of life,followed closely by second decade. Juvenile OF was seen in a

Fig. 1. (A) Panoramic radiograph showing OF presenting as a well-defined corticated radiolucradiolucent radiopaque lesion with ill-defined margins (case no. 18). (C) Ossifying fibroma amandible (case no. 21). (D) Three-dimensional reconstruction showing lesional extent of JO

comparatively younger age group ranging from 8 to 28 years, withthe trabecular variant presenting during the first decade. Three casesof PsJOF and 2 of TrJOF were identified in the present series.

The OF and JOF were almost equally distributed in men andwomen with a ratio of 8:9 and 2:3, respectively. The lesions werefound to vary in size, with the smallest lesionmeasuring 2.5 × 1.2 cm (Fig. 1A) to a maximum of 10.5 × 2.5 cm (Fig. 1B).

Most cases of OF (n = 13) were found to occur in the posteriormandible, whereas JOF was predominantly observed in the an-terior maxillary segment (n = 3) with extension into the maxil-lary antrum.

Radiographically, OF showed variable appearance ranging fromcompletely radiolucent (n = 7), mixed (n = 5), to completelyradiopaque (n = 5) appearance. Many tumors showed well-definedsclerotic borders (n = 8), whereas others showed diffuse margins. Acase of OF associated with ABC formation showed characteristicballooning expansion of the cortex. Of the 5 cases of JOF studied, 4were completely radiolucent with ill-defined margins. One case ofTrJOF showed radiopacity with well-defined sclerotic margins (Fig. 1).

Table 1 summarizes the clinical and radiographic features.An incisional biopsy was performed for all cases, and concor-

dance between the incisional and excisional biopsy diagnosis wasseen in 20 of 22 cases. Two cases previously diagnosed as fibrousdysplasia eventually proved to be OF and TrJOF, respectively, onexamination of excisional tissue.

Histologically, supporting stromal tissue was fibrous in 8 cases ofOF, although focal areas of cellularity were noted particularly aroundareas of ossification. Five cases had highly cellular (Fig. 2A) and 4cases had moderately cellular supporting stromal background. Allcases of JOF analyzed showed a highly cellular supporting cellularframework. The stromal cells were plump and tightly packed withlarge vesicular nuclei and hardly discernible cytoplasm.

ent lesion (case no. 19). (B) Ossifying fibroma involving mandible appearing as a mixedssociated with ABC showing characteristic ballooning enlargement of inferior border ofF in anterior maxilla (case no. 22).

Table 1Clinical and radiographic features of 22 cases of OF and JOF studied

Serialno.

Age(y)

Sex Site Radiographic appearance

1 38 F Left posterior maxilla Diffuse radiopacity with sclerosis2 24 M Right posterior mandible Well-defined radiopacity3 24 M Left posterior mandible Mixed radiopaque and radiolucent

lesion with sclerotic borders4 20 M Left anterior maxilla Radiolucency extending into sinus5 12 F Left posterior mandible Mixed radiopaque and radiolucent6 20 M Right posterior mandible Well-defined radiopacity7 45 F Right posterior mandible Mixed radiopaque and radiolucent8 8 F Left posterior mandible Well-defined radiolucency9 53 F Left posterior mandible Radiolucent with sclerotic border10 22 F Left anterior mandible Radiolucent11 28 M Anterior maxilla, palate,

and antrumRadiolucent with ill-definedmargins

12 45 F Left posterior mandible Ill-defined radioopacity13 11 M Left posterior maxilla Radiolucent14 21 F Right posterior maxilla,

palate, and antrumIll-defined radiolucency

15 8 M Left posterior mandible Ill-defined radiopacity16 19 M Left posterior mandible Ill-defined mixed radiolucent

and radiopaque17 22 M Left posterior mandible Radiolucent with ill-defined

borders18 38 F Right anterior mandible Mixed radiolucent radiopaque

lesion with ill definedmargins

19 28 F Left posterior mandible Well-defined radiolucency withsclerotic borders

20 17 F Left posterior mandible Well-defined unilocularradiolucency

21 10 M Left posterior mandible Well-defined radiolucency withsclerotic borders and ballooningexpansion of inferior border ofmandible

22 10 F Left anterior maxilla Radiopacity with well-definedsclerotic margins

Note: cases number 4, 8, 11, 14, and 22 were diagnosed as JOF, and the rest was OF. Findicates female; M, male.Anterior maxilla/mandible—from central incisor to distal of canine.Posterior maxilla/mandible—from mesial of first premolar to distal of third molar.

200 A.B. Urs et al. / Annals of Diagnostic Pathology 17 (2013) 198–203

Analysis of mineralization patterns revealed considerable overlapbetween various types of ossification and calcification (Fig. 2B-D).Mature well-mineralized bony trabeculae with osteoblastic rimmingand a few osteocytic lacunae were observed in most cases of OF (n =13) (Fig. 3A). Immaturewoven bonewas observed in 4 cases of OF andboth cases of TrJOF analyzed (Fig. 3B). In addition, osteoid seams wereevident in both cases of TrJOF.

The pattern of ossification in OF varied from small and large roundossicles containing osteocytic lacunae (n = 3) to darkly basophilicglobules of cementum-like material (n = 7) with both patternsappearing concurrently in certain cases (Fig. 2B-D). Variably shapedpsammoma bodies with basophilic centers and peripheral eosino-philic rims were noted in all 3 cases of PsJOF. Lesions were sharplydemarcated from sinus tissue in cases involving the maxillary antrum(Fig. 4).

Secondary changes were frequently observed in addition toprimary tumor pathology, the most significant of which was theformation of ABC-like areas. Association with ABC formation wasnoted in a single case of OF and one of TrJOF. Large blood-filled spacesdevoid of an endothelial lining and associated with few giant cellswere seen in both instances (Fig. 5). Myxoid degeneration was notedin 1 case of maxillary PsJOF, with the presence of mineralized areaswithin the myxoid component.

Focal areas of inflammation and hemorrhage were observed inmany cases of OF and JOF.

Table 2 highlights the histologic details of all cases studied.

Various treatment modalities such as curettage, en bloc resection,and segmental resection were performed for the cases underconsideration. Follow-up data were available for 17 cases, and 5cases were lost to follow-up. One case of PsJOF (case no. 14) recurredafter a period of 1.1 years. This patient had been treated by localsurgical excision.

4. Discussion

The term OF has been used to describe clinically and microscop-ically heterogeneous lesions of the skull. Proper identification of thesedistinct entities is important not only for academic purposes but alsofor proper diagnosis and therapeutic management.

Although OF has principally been found in the jaws, it has alsobeen reported in the frontal, ethmoid, sphenoid, temporal bones,orbit, and anterior cranial fossa [8]. Ossifying fibroma affecting thejaws exhibits a variable behavior ranging from slow growth tooccasionally aggressive local destruction. Although the growth of OF isdescribed as concentric with outward expansion approximately equalin all directions, overall, the growth potential of OF is unpredictable,and there is no clinical or microscopic features that can be usedeffectively to predict behavior [9,10].

Juvenile OF is also referred to as juvenile active OF or juvenileaggressive OF. It is a benign bone-forming neoplasm and is a variant ofOF occurring in the craniofacial skeleton of young patients [10]. Thelesion is not encapsulated, although well demarcated from thesurrounding bone [4].

The present study has analyzed the clinical, radiographic, andhistopathologic features to understand the dynamics of theseseparate entities.

A total of 22 cases of OF and JOF over a 4.5-year period fromJanuary 2007 to June 2011 were compiled. A systematic reviewconducted by MacDonald-Jankowski [11] showed the incidence of OFin different population/nationality with number of hospitals and citiesmentioned from 1968 to 2009. The study revealed that from 1990 to2009 (last 2 decades), the incidence per year of OF varied from a lowof 0.03 in a Mexican population to a maximum of 3.8 in a Japanesepopulation. In comparison with this, the incidence of OF and JOF ishigh in the North Indian population studied in this institute over aperiod of 4.5 years (4.88 per year). This indicates that OF alongwith itscounterpart JOF is more common in the studied institutionalpopulation viz-à-viz other populations studied. The institute underconsideration being a tertiary referral institute may partially accountfor this high incidence rate.

The present study revealed OF having an age distribution between8 and 53 years with peak in third decade, followed closely by seconddecade. Chang et al (2008) [12] have reported an age distribution of16 to 62 years with amean of 36 years in a Taiwan Chinese population.Olgac et al (2006) [13] has shown an occurrence of OF between 3 and85 years. Hence, the age distribution seems to vary over a wide rangeand differs in different populations.

In comparison, JOF was restricted to a younger age group varyingfrom 8 to 28 years with PsJOF occurring between 20 and 28 years andTrJOF between 8 and 10 years. Margo et al [14] have reported PsJOFoccurring between 10 and 25 years. El Mofty [5] has reported anaverage age range of 8.5 to 12 years for TrJOF. Our findings correlatewell with reported literature.

Both OF and JOF were almost equally distributed among both thesexes. Jones et al (2006) [15,16] and Chang et al (2008) [12] havereported a higher female predilection of OF. Literature for JOF,however, reveals male predominance [5,6]. Posterior segment of thejaws was primarily involved in most cases. This correlates withprevious reports showing 25 of 39 cases involving posterior mandiblein the study of Olgac et al (2006) [13] and 23 of 28 cases in the study ofChang et al [12]. The posterior mandibular quadrant appears to bemost affected by OF (n = 13).

Fig. 2. (A) Spindled cells in a case of OF having cellular supporting stroma (case no. 7). (B) Microphotograph with basophilic globules of cementum-like material (cementicles) in acellular stroma. Inset shows cementicle under high magnification (case no. 17). (C) Cementicles and bony trabeculae in a cellular background (case no. 12). (D) Ovoid osteoblast-lined ossicle containing osteocytes lying within a cellular stroma (case no. 16).

201A.B. Urs et al. / Annals of Diagnostic Pathology 17 (2013) 198–203

Johnson et al [17] have reported that 90% of PsJOF occurred insinonasal area and jaws and 10% in the calvaria. Of the former group,70% was in the paranasal sinuses; 20%, in maxilla; and 10%, inmandible. An important difference between PsJOF and TrJOF is thatTrJOF is a gnathic lesion affecting the jaws with a predilection for themaxilla, whereas PsJOF predominantly involves the paranasal sinuses

Fig. 3. (A) Mature bony trabeculae with osteoblastic rimming and osteocytes within lacun

[5]. The same holds true for the study under consideration where allcases of PsJOF involved the maxillary sinus.

The radiographic appearance of OF varies, as substantiated in thepresent study. Chang et al (2008) [12] have shown a varyingradiologic presentation of OF. They have also emphasized that only7 of 28 cases showed sclerosis of the periphery. The present study

ae (case no. 15). (B) Immature bone showing large amount of osteoid (case no. 18).

Fig. 4. Psammoma bodies in a highly cellular background in a case of PsJOF. Note sharpdemarcation from the sinus tissue with presence of calcification within it (case no. 14).

Table 2Histopathologic features of 22 cases of OF and JOF studied

S. no. Nature of stroma Mineralization pattern Secondary changes

1 Fibrous stroma withfocal cellularityaround ossification

Cementicles and well-formed mature bonytrabeculae

–

2 Fibrous Well-formed mature bonytrabeculae

–

3 Fibrous stroma withfocal cellularityaround ossification

Well-formed mature bonytrabeculae

–

4 Highly cellular Rounded ossificationresembling psammoma

–

5 Fibrous Well-formed mature bonytrabeculae

Hemorrhage

6. Fibrous Few ossicles and fewcementicles

–

7 Highly cellular Few cementicles Inflammation8 Highly cellular Irregular immature bony

trabeculae with osteoidseams

–

9 Cellular Mature bony trabeculae Inflammation10 Cellular Irregular immature bony

trabeculaeHemorrhage aroundtrabeculae, foci ofinflammation/necrosis

11 Highly cellular Psammomatoidcalcification

–

12 Cellular Mature bony trabeculaewith very few cementicles

Inflammation andminor hemorrhage

13 Highly cellular Very small cementicles –

14 Highly cellular Psammomatoidcalcification

Inflammation, looselymyxoid degeneration

15 Fibrous Mature bony trabeculae –

16 Cellular Mature bony trabeculaeand ossicles

Inflammation

17 Highly cellular Cementicles18 Highly cellular Immature bony trabeculae

with osteoid, ossicles, andfew cementicles

Hemorrhage

19 Loosely fibrous Few immature bonytrabeculae

Inflammation andhemorrhage

20 Fibrous Mature bony trabeculae Little hemorrhage21 Highly cellular Few immature bony

trabeculae with osteoidand cementicles

ABC formation,hemorrhage,hemosiderin formation

22 Highly cellular Immature irregulartrabeculae with osteoidseams

ABC formation

202 A.B. Urs et al. / Annals of Diagnostic Pathology 17 (2013) 198–203

revealed cortication at the periphery/sclerosis in younger patients.Although studied literature indicates that lesions in younger in-dividuals are completely radiolucent and that calcification occursincreasingly with age, the present study showed no correlationbetween the age of patient and radiographic appearance [18].

Microscopically, fibrous stroma in most instances was character-ized by dense collagen fibers intermingling with few fibroblasts andshowing increased cellularity around areas of mineralization. Thesecells resembled potential osteoblasts. In cellular stroma, the connec-tive tissue was composed of sheets of spindled fibroblasts with areasof storiform arrangement. In tumors with highly cellular stroma,stellate cells were seen intermingling with the spindle cells in aloosely fibrous background. The histopathologic interpretationrevealed that a fibrous stroma is more often associatedwith formationof mature bony trabeculae. When correlated clinically, most of thesewere seen involving the mandible. In cases of cellular stroma, thepattern of calcification varied with most lesions occurring in themandible again.

The pattern of ossification in highly cellular stroma was psammo-matoid type of calcification along with immature irregular bonytrabeculae surrounded by osteoid seams. Cementicles were also noted

Fig. 5. (A) Aneurysmal bone cyst formation associated with OF. Note large blood-filled spacesof OF associated with ABC formation (case no. 21).

in a few cases. There was equal involvement of maxilla and mandible,although most of the maxillary cases were JOF and the mandibularwere OF.

adjacent to the primary tumor. (B) High-power photomicrograph showing cellular area

203A.B. Urs et al. / Annals of Diagnostic Pathology 17 (2013) 198–203

Ossifying fibroma are neoplasms well demarcated and separatedfrom adjacent cancellous bone or soft tissue by an expanded andattenuated layer of cortical bone. They usually demonstrate acapsule on macroscopic and microscopic examination [19]. Becauseall cases of OF in the present study arose in the tooth-bearing areasof the jaw, an origin of these tumors from periodontal ligamentseems to be justified.

Juvenile OF is considered as a neoplastic product of the myxoidtissue precursor of cartilage and bone that is particularly prominent inthe septa of paranasal sinuses where it forms the mucoperiosteumbetween the bone and epithelium. Themyxoid tissue of JOF is thoughtto be derived from this component, which occasionally forms tumor inyoung children composed only of myxoid tissue. In active growth,cellular areas develop from the myxoid tissues and become thestromal cells of JOF. Within this, the ossicles develop, which arecharacteristic of JOF [17]. Close association with the maxillary antrumin 4 of the 5 cases of JOF reported in the current study lends support tothe aforementioned hypothesis.

The present study has shown 2 cases of ABC formation: one inTrJOF and the other in OF. Aneurysmal bone cyst formation in bothhistologic variants of JOF has been documented. It is said to developinitially as a focal myxoid change in the stroma with hemorrhage andosteoclastic giant cells, followed by gradual expansion and formationof cysts with thin fibrous walls. As was seen in our study, these cyststended to occur more commonly in younger patients in the first andsecond decades of life [5].

Hemorrhage and inflammation were secondary changes quitecommonly observed. Hemorrhage could be due to excessive vascu-larity, which can be associated with these lesions. Inflammation maybe secondarily induced.

To conclude, the current study has collated and correlated theclinical, radiographic, and histopathologic features of OF and JOF.Ossifying fibroma showed a predilection for mandible, and JOF, foranterior maxilla. Histologically, fibrous and cellular stroma withvarying types of mineralization patterns with considerable overlapbetween the types of mineralized/calcified material was noted in OF.Juvenile OF, on the other hand, had highly cellular stroma andcharacteristic mineralization patterns in most instances. Whenhistologic parameters were correlated with the clinical ones, nosignificant pattern of correlation emerged. The pathogenesis of these

lesions can be elucidated to be different in that OF arises fromperiodontal ligament, and JOF seems to be a neoplastic product of themyxoid tissue precursor of cartilage and bone of paranasal sinuses.

References

[1] Liu Y, You M, Wang H, et al. Ossifying fibromas of the jaw bones: 20 cases.Dentomaxillofac Radiol 2010;39:57-63.

[2] Waldron CA. Fibro-osseous lesions of the jaws. J Oral Maxillofac Surg 1985;43:249-62.

[3] Waldron CA. Fibro-osseous lesions of the jaws. J Oral Maxillofac Surg 1993;51:828-35.

[4] Pinos AJS, Olmedo AJ, Gaya MVO, et al. Juvenile ossifying fibroma: a case study.Med Oral Patol Oral Cir Bucal 2004;9:454-8.

[5] El-Mofty S. Psammomatoid and trabecular juvenile ossifying fibroma of thecraniofacial skeleton: two distinct clinicopathologic entities. Oral Surg Oral MedOral Pathol Oral Radiol Endod 2002;93:296-304.

[6] Slootweg PJ, Panders AK, Koopmans R, et al. Juvenile ossifying fibroma. An analysisof 33 cases with emphasis on histopathological aspects. J Oral Pathol Med 1994;23:385-8.

[7] Kramer IRH, Pindborg JJ, Shear M. World Health Organization. Internationalhistological classification of tumors. Histological typing of odontogenic tumors,2nd ed. Berlin: Springer-Verlag; 1992.

[8] Som PM, Lidov M. The benign fibroosseous lesion: its association with paranasalsinus mucoceles and its MR appearance. J Comput Assist Tomogr 1992;16:871-6.

[9] White SC, Pharoah MJ. Diseases of bone manifested in the jaws. In: White SC,Pharoah MJ, editors. Oral radiology. Principles and interpretation. 5th ed. St. Loius,(Mo): Mosby; 2004. p. 412.

[10] Brannon RB, Fowler CB. Benign fibro-osseous lesions; a review of current concepts.Adv Anat Pathol 2001;8:126-43.

[11] MacDonald-Jankowski DS. Ossifying fibroma: a systemic review. DentomaxillofacRadiol 2009;38:495-513.

[12] Chang CC, Hung HY, Chang JY, et al. Cental ossifying fibroma: a clinicopathologicstudy of 28 cases. J Formos Med Assoc 2008;107:288-94.

[13] Olgac V, Koseoglu BG, Aksakalli N. Odontogenic tumors in Istanbul: 527 cases. Br JOral Maxillofac Surg 2006;44:386-8.

[14] Margo CE, Ragsdale BD, Perman KI, et al. Psammomatoid (juvenile) ossifyingfibroma of the orbit. Ophthalmology 1985;92:150-9.

[15] Jones AV, Franklin CD. An analysis of oral and maxillofacial pathology found inadults over a 30-year period. J Oral Pathol Med 2006;35:392-401.

[16] Jones AV, Franklin CD. An analysis of oral and maxillofacial pathology found inchildren over a 30-year period. Int J Paediatr Dent 2006;16:19-30.

[17] Johnson LC, Usefi M, Vinh TN, et al. Juvenile active ossifying fibroma: its nature,dynamic and origin. Acta Otolaryngol Suppl 1991;488:1–40.

[18] MacDonald-Jankowski DS. Cemento-ossifying fibromas in the jaws of Hong KongChinese. Dentomaxillofac Radiol 1998;27:298-304.

[19] Su L, Weathers DR, Waldron CA. Distinguishing features of focal cemento osseousdysplasia and cement ossifying fibromas. A pathologic spectrum of 316 cases. OralSurg Oral Med Oral Pathol Oral Radiol Endod 1997;84:301-9.