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Clinical

Paper

Clinical Pathology

Juvenile ossifying fibroma of the jaw: a retrospective study of 15cases J.

Han,

L.

Hu,

C.

Zhang,

X.

Yang,

Z. Tian,

Y.

Wang,

L. Zhu,

C.

Yang,

J.

Sun,

C.Zhang,

J.

Li,

L. Xu:

Juvenile

ossifying

fibroma

of

the

jaw:

a

retrospective

study

of

15cases. Int. J. Oral Maxillofac. Surg. 2016; 45: 368–376. # 2015 InternationalAssociation of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rightsreserved.

J.

Han1,5,

L.

Hu1,5,

C.

Zhang2,X.

Yang1,

Z.

Tian2,

Y.

Wang1,

L.

Zhu3,C.

Yang4,

J.

Sun1,

C.

Zhang1,

J.

Li2,L.

Xu1

1Department of Oral and Maxillofacial–Headand Neck Oncology, Ninth People’s Hospital,Shanghai Jiao Tong University School ofMedicine, Shanghai, China; 2Department ofOral Pathology, Ninth People’s Hospital,

Shanghai Jiao Tong University School ofMedicine, Shanghai, China; 3Department ofRadiology, Ninth People’s Hospital, ShanghaiJiao Tong University School of Medicine,Shanghai, China; 4Department of OralSurgery, Ninth People’s Hospital, ShanghaiJiao Tong University School of Medicine,Shanghai, China

Abstract. The management of patients with juvenile ossifying fibroma (JOF) remainscontroversial.

To

explore

the

correlations

between

different

treatments

and

the patient

prognosis,

15

cases

of

JOF

of

the

jaw

were

reviewed.

Five

patients

weremale and 10 were female. Patient age at the time of disease onset ranged from 7 to18 years (mean 10.9 years). Nine tumours were located in mandible and six in themaxilla.

These

cases

typically

manifested

clinically

as

painless

swelling

of

the

jaw(9/15,

60%);

40%

(6/15)

of

the

cases

were

associated

with

pain,

diplopia,

stuffynose, and/or rapid growth. Images of JOF can show a radiolucent, mixed, or ground glass-like appearance. Pathological examinations revealed 10 cases of juveniletrabecular

ossifying

fibroma

(JTOF)

and

five

cases

of

juvenile

psammomatoid ossifying

fibroma

(JPOF).

In

terms

of

the

treatment

plan,

six

patients

initiallyreceived radical surgery; nine patients underwent conservative treatment, amongwhom six (6/9, 66.7%) had one or more recurrence. At the end of the follow-up period,

12

patients

had

no

evidence

of

tumour

recurrence

and

three

cases

were

alivewith

a tumour.

In

summary,

surgeons

should

develop

the

surgical

plan

according

tothe extent of the lesion, relapse status, growth rate, and family choice, and these patients should be followed up closely.

Key words: jaw; JOF; JPOF; JTOF; treatment.

Accepted for publication 7 December 2015Available online 28 December 2015

Ossifying fibroma (OF) is a type of benignfibro-osseous lesion. This tumour is char-acterized

by

clear

boundaries

and

cell-richfibrosis,

and

contains

varying

amounts

of

calcified tissue resembling bone, cemen-tum, or both. OF lesions are classified asconventional

ossifying

fibroma

and

juve-nile ossifying

fibroma

(JOF).1 Conven-

tional OF is mainly seen in adults. JOFusually occurs in children or adolescents,

and it is therefore also known as juvenileactive/aggressive ossifying fibroma(JAOF).

In

2005,

the

World

Health

Orga-nization

(WHO)

noted

that

the

age

at

onset

of JOF is 15 years and younger.1However,

JOF has also been documented in adults.2,3

JOF

has

characteristics

of

aggressivegrowth,

is

associated

with

damage

to

the

cortical bone, and may involve the nasalcavity, eyes, and even cerebrum. Howev-

er, there are no reports of cases of malig-nant transformation or metastasis. Theimaging

characteristics

of

JOF

show

expansive,

well-defined

radiolucent

or

mixed images that are separ ated fromthe surrounding normal bone.

4Based on

histopathology,

JOF

is

divided

into

the

Int. J. Oral Maxillofac. Surg. 2016; 45: 368–376 http://dx.doi.org/10.1016/j.ijom.2015.12.004, available online at http://www.sciencedirect.com

5 These authors contributed equally to thiswork.

0901-5027/030368+ 09 # 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

http://dx.doi.org/10.1016/j.ijom.2015.12.004http://dx.doi.org/10.1016/j.ijom.2015.12.004http://dx.doi.org/10.1016/j.ijom.2015.12.004http://dx.doi.org/10.1016/j.ijom.2015.12.004http://dx.doi.org/10.1016/j.ijom.2015.12.004

8/19/2019 Pi is 090150271501468 x

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following

two

subtypes:

juvenile

psammo-

matoid ossifying fibroma (JPOF) and juve-nile trabecular ossifying fibroma (JTOF). Inaddition, JOF usually contains multinucle-ated

giant

cells,

whereas

conventional

OF

does not.5,6Conventional OF usually pre-

sents as a slow-growing mass of bone ex- pansion that is usually without symptoms

and rarely recurs; conversely, 38.5% of JOFcasesare associated with mandibular swell-ing and pain and there may be short-termrapid growth.7 Therefore, surgeons should consider clinical features, radiological

characteristics, and pathological featureswhen diagnosing JOF. Key points to beconsidered include age, status of growth,

and histopathology.8

The management of patients with JOFremains controversial. According to theliterature, the recurrence rate after surgery

is approximately 30–58%.1,3,9–11

There-fore, designing an appropriate treatment

plan for

the

JOF

patient

could

help

toimprove the prognosis and quality of life.

Depending on biological behaviour and the lesions involved, treatment can be

conservative

or

radical.12 Some

research-

ers have emphasized the aggressivegrowth characteristics and high recurrencerate of JOF, lead ing them to advocate localradical

surgery.4,13,14 In

contrast,

others

consider that conservative treatment ismore beneficial for young patients whentaking into account their growth and de-

velopment, their appearance, and the pres-ervation of chewing and nervefunctions.

12,15,16

This study was performed to review theclinical features, imaging features, and

pathological characteristics of 15 casesof JOF treated at the authors’ institution.The relationships between the different

treatment options and the prognosis arediscussed and the most suitable treatmentsfor JOF are explored.

Materials

and

methods

A total of 15 patients with JOF treated between 2005 and 2014 in the Departmentof Oral and Maxillofacial–Head and Neck

Oncology of the study institution were

included.

Each

patient’s

medical

history

was reviewed carefully to collect clinicaldata (including age, sex, disease location,symptoms, surgical approach, and prog-nosis),

radiological

features,

histological

type, and other information.According to the anatomical location,

the mandible was divided into anterior

(left canine to right canine), posterior (first premolar to third molar), angle, ramus,and condyle. The maxilla was divided intoanterior (left canine to right canine) and posterior (first premolar to the maxillary

tuberosity). Imaging data were used toanalyze the lesion and surrounding tissue boundaries and the internal radiographic

architecture. The internal radiographic ar-chitecture was divided into mixed radi-opaque and radiolucent, unilocular or multilocular radiolucency, and ground

glass opaque. An oral pathology specialistclassified the histological subtype as either

JTOF

or

JPOF

based

on

the

2005

WHOclassification criteria for head and neck

cancer.1Surgeries performed included

conservative treatments (curettage and

Juvenile ossifying fibroma of the jaw 369

Table 1. Clinical information, treatment, and follow-up information for the 15 cases of juvenile ossifying fibroma (JOF).

Patient No./sex

Age atonset(years)

Age atoperation(years)

Size

Symptoms

Location

Surgery

Follow-up(months);outcome

Conservative treatment 1/M 8 8 4.5 4 Swelling Right maxilla Curettage 72; alive

with tumour 2/F 14 19 2 1.5 Swelling Left maxilla

(posterior)Curettage 20; alive

with tumour 3/M 13 13 5 4 Swelling Right mandible

(posterior)Enucleation 38; NED

4(R)/M

18

20

3

2

Swelling,

pain

Left

maxilla

Curettage

124;

alivewith tumour

5(R)/F 9 16 6 4 Swelling Right mandible(posterior)

Curettage/resection + fibula 95; NED

6(R)/F

12

15

5

4

Swelling

Left

mandible(posterior/angle)

Curettage/resection

+

iliac

crest

146;

NED

7(R)/M 15 17 9 8 Swelling,rapid growth

Right mandible(posterior)

Curettage/resection + fibula 105; NED

8(R)/M

10

12

10

7

Swelling,rapid growth

Left

mandible

Curettage/resection

+

fibula

40;

NED

9(R)/F 9 19 9 8 Swelling,stuffy

nose,diplopia

Right maxilla Curettage/resection + fibula 128; NED

Radical treatment

10/F 13 19 12 8 Swelling Left mandible(posterior)

Resection + fibula 87; NED

11/F 11 11 6 4 Swelling Right mandible(posterior)

Resection + iliac crest 58; NED

12/F 7 7 6 4.5 Swelling Left mandible(posterior/angle)

Resection + iliac crest 36; NED

13/F

7

7

3

2

Swelling

Right

mandible(condyle)

Resection

+

costal

cartilage

15;

NED

14/F 7 8 4 3.5 Swelling, pain,diplopia,rapid

growth

Left maxilla(posterior)

Resection 18; NED

15/F 11 15 6 4 Swelling, pain,rapid growth

Right maxilla Resection 13; NED

F, female; M, male; NED, no evidence of disease; (R), recurrence.

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enucleation) and radical surgery (com-

plete resection with or without reconstruc-

tion).Due to the retrospective nature of this

study, it was granted an exemption from

requiring ethics approval in writing by theinstitutional review board of the studyhospital.

Results

Clinical data

Of the 15 cases of JOF, five were male and

10 were female, giving a male to femaleratio of 1:2. The age at onset ranged from 7

to 18 years (mean 10.9 years). The ages of JTOF patients ranged from 9 to 13 years

(mean 11 years) and the ages of JPOF patients ranged from 7 to 18 years (mean10.9 years). The disease duration ranged

from 2 weeks to 5 years, with an average

of 18.2 months (Table 1).

The lesions

were

located

in

the

mandiblein nine cases and in the maxilla in six cases,with three involving the maxillary sinus. In

mandibular cases, the site was most often posterior (5/9, 55.6%), followed by a com- bination of posterior and angle (2/9,22.2%). For the upper jaw, unilateral in-

volvement of the entire maxilla (4/6,66.7%) was most common, followed bythe posterior of the maxilla (2/6, 33.3%).Sixty percent (9/15) of cases manifested

clinically as a slowly growing painlessmass in the jaw. Forty percent of cases(6/15; four cases involving the maxilla and

two involving

the

mandible)

presented with pain, diplopia, stuffy nose, and/or rapid growth. Clinical examinationrevealed an immobile hard mass, and

egg shell crackling was occasionally noted when a cystic lesion developed.

Before surgery, most patients had a

diagnosis of ossifying fibroma (10/15,

66.7%).

Other

diagnoses

included

ameloblastoma (n = 2, 13.3%), fibrous dysplasia(n = 1, 6.7%), chondromyxoid fibroma

(n = 1, 6.7%) and aneurysmal bone cyst(n = 1, 6.7%).

Imaging features

Images of all patients showed a mass with

clear boundaries. There was generally nosoft tissue involvement. Computed tomog-raphy (CT) and/or panoramic images wereavailable for a total of 13 patients. Accord-

ing to the component and proportion of

soft tissue

and

hard

tissue

in

the

internalstructure, the tumour masses presented asmixed radiopaque and radiolucent (5/13,

38.5%), unilocular or multilocular radio-lucency (3/13, 23.1%), and ground glassopaque (4/13, 30.8%) (Table 2). Three of

370 Han et al.

Table 2. Radiographic features and pathology of 15 cases of juvenile ossifying fibroma (JOF).

Pathology Patient No. Radiographic features

JTOF

4

Ground

glass

opaque,

well-defined

border 6 Mixed radiopaque and radiolucent, well-defined border 7 Multilocular radiolucency, well-defined border 11 Mixed radiopaque and radiolucent, well-defined border 1 Mixed radiopaque and radiolucent, well-defined border 12 Unilocular radiolucency, well-defined border

8* Multilocular radiolucency, well-defined border 2 Not available13 Mixed radiopaque and radiolucent, well-defined border 14* Not available

JPOF 10 Ground glass opaque with central radiolucency, well-defined border 3 Mixed radiopaque and radiolucent, well-defined border 5 Ground glass opaque with central radiolucency, well-defined border 9 Multilocular

radiolucency

with

ground

glass

opaque,

well-defined

border 15 Ground glass opaque with central radiolucency, well-defined border

JTOF, juvenile trabecular ossifying fibroma; JPOF, juvenile psammomatoid ossifying fibroma.* JTOF with aneurysmal bone cyst.

Fig.

1.

Imaging

findings

in

juvenile

ossifying

fibroma

(JOF):

case

15.

(A)

Preoperative

axial

CT

showing

a

bulging

mass

in

the

maxilla,

a

ground glass-like appearance, and central cystic changes. (B) Preoperative sagittal CT showing a mass intruding into the maxillary sinus and rootdisplacement. There is a high-density shadow in the surrounding area.

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the ground glass opaque cases were asso-ciated with central radiolucent regions(Fig. 1), and one case had multiple radio-lucent regions associated with ground

glass plaques. CT imaging and three-di-

mensional

reconstruction

of

the

differentorientations showed cortical bone destruc-tion and absorption in nine cases (9/13,

69.2%), with adjacent tooth or root displacement in seven (7/13, 53.8%).

Histopathological features

General examination revealed that JOFwas usually a grey mass with a clear

boundary. Tumour sizes ranged from 2to 12 cm, with an average of 6.03 cm.Those with diameters 5 cm accounted for 66.7% (10/15) of cases. Dissection of

the tissue

showed

gravel-like

or

hard

tis-sue. Of the 15 cases of JOF, 10 were JTOFand five were JPOF (Table 2). Under themicroscope, JTOF demonstrated a cell-

rich fibrous tissue background with a stripof osteoid-containing cells or immaturetrabecular cells. The trabecular bone wassurrounded by a layer of hypertrophic

osteoblasts, which together formed agrid-shaped region. Some regions showed aggregations of osteoclast-like multinu-cleated giant cells. Twenty percent (2/

10) of cases were associated with an an-eurysmal bone cyst (Fig. 2A, C). JPOFwas characterized by fibroblastic stromaand basophils containing sand-like struc-

tures that resembled cementum (Fig. 2B).

Types of surgery and prognosis

All patients underwent surgical treatment,including conservative treatment and localradical surgery. Nine patients first under-

went conservative treatment, amongwhom six had one or more recurrence,giving a recurrence rate of 66.7% (6/9).Among those experiencing a recurrence,

five underwent local radical surgery and

one underwent local curettage. Cases 4, 5,6, and 7 had recurrence after 8 months, 2years, 6 months, and 11 months, respec-tively. Case 8 had local recurrences after

twice undergoing curettage, at 6 months

and

7

months

after

the

procedure.

Case

9had recurrences at 5 years and 15 monthsafter surgeries. Overall, recurrence oc-

curred at between 6 months and 5 years,with an average of 17.1 months. Six patients initially had local radical surgeryand none had a recurrence.

Nine patients underwent reconstructive

surgery.

One

patient

with

JOF

in

the

max-illa underwent a fibula muscle flap transplantation (Fig. 3). Of the eight mandible


Fig. 2. Histopathological features of juvenile ossifying fibroma (JOF). (A) Juvenile trabecular ossifying fibroma (JTOF) (case 4) has a cell-richfibrous

tissue

background

with

cell-containing

immature

trabecular

bone.

A

layer

of

hypertrophic

osteoblasts,

which

form

a

grid-like

structure,surrounds the trabecular bone. (B) Juvenile psammomatoid ossifying fibroma (JPOF) (case 15) has a fibrous stroma containing sphericalmineralized bodies. The bodies are like cementum, with basophilic cores and an eosinophilic exterior. (C) Aneurysmal bone cyst formed withinJTOF (case 8). The capsule is filled with red blood cells.

Fig. 3. Imaging findings in juvenile ossifying fibroma (JOF): case 9. (A) The lesion recurred after multiple maxillary curettages. Axial CT showing multiple transparent shadows accompa-nied

by

ground

glass-like

plaques.

(B)

CT

reconstruction

revealing

lesions

involving

the

nasalcavity and orbital cavity, as well as cortical discontinuity. (C) Immediate CT three-dimensionalreconstruction after maxillary expansive resection and fibula muscle flap transplantationshowing

ideal

recovery

of

the

jaw

morphology.

(D)

Axial

CT

showing

a

metal

plate

of

thecorrect shape without evidence of recurrence at 1 year and 2 months after surgery.

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cases,

three

underwent

a

free

iliac

crest

graft (Fig. 4), one case with condyle in-volvement had a costal cartilage transplantation (Fig. 5), and four casesunderwent

fibula

flap

transplantation

(Fig. 6).The 15 patients were followed up for

13–146 months, with an average follow-

up of 66.3 months. The follow-up of patients with multiple surgeries wasrecorded from the date of the initial sur-gery (Table 1). All patients were alive atthe end of follow-up: 12 patients had no

evidence of disease (tumour-free survival)and three patients were living withtumours.

Discussion

JOF is a variant of OF that occurs mainly

in the cranial and facial bones of young patients. JOF can lead to severe morpho-

logical

and

functional

defects.

JOF

and other benign fibrous lesions have great

similarities in terms of their clinical fea-tures, imaging characteristics, and pathol-ogy. Therefore, a systematicunderstanding of the disease can enable

clinicians to perform an accurate diagno-sis, develop a reasonable treatment plan,and predict the prognosis. This study ret-rospectively analyzed 15 cases of JOF

with regards to their clinical, radiological,and pathological features and analyzed the prognoses associated with the differenttreatment options. The aim was to develop

more

appropriate

treatment

methods.

Thisstudy reports on JOF in a relatively largecohort of Chinese patients.OF can occur at any age, but is mainly

seen in adults aged 30–40 years. JOF patients are relatively young. In the2005 WHO definition, the age at onsetof JOF is 15 years. However, according

to a report by Johnson et al., the age atonset of JOF ranges from 3 months to 72years.

3Studies reported in the literature

have indicated that the average age atonset of the two JOF subtypes differ s:the age at JPOF onset is 10 to 25 years,

10

whereas JTOF patients are relatively

younger, at 8.5–12 years.4The ages of

the patients with the two subtypes in the present study were similarly young: theaverage age of JTOF patients was 11 years

and the average age of JPOF patients was10.9 years. In terms of the sex distribution,various case reports in the literature haveshown a slight difference.

3,5In the present

group of patients, JOF was more common-ly seen in females, with a male to femaleratio of 1:2.JTOF usually occurs in the jaw,

4where-

as JPOF occurs mainly in the paranasal

sinus bone wall.3,17

There are a f ew casereports of JPOF in the jaw.

2,18In this

study, the lesions in the 15 patients withJOF (10 cases of JTOF and five cases of JPOF) all occurred in the jaw. Different

reports

have

shown

different

sites

of

dis-ease onset.5,19,20

In this study, there wereslightly more patients with disease in thelower jaw (nine cases) than in the upper

jaw (six cases).Locally aggressive growth is an impor-

tant clinical feature that differentiates JOFfrom conventional OF. It has been

reported that 38.5% of JOF patients haveswelling with pain,

7while conventional

OF is associated with painless swelling inthe jaw. When the tumour is located in the

upper jaw and becomes large, it can in-volve the surrounding tissues such as theeyes

17,21and nasal cavity,

22thereby

resulting in exophthalmos, nasal conges-

tion, and other symptoms. In the group of patients presented here, 40% (6/15; four cases involving the maxilla and two in-volving the mandible) had pain, diplopia,

stuffy nose, and/or rapid tumour growth.The imaging characteristics of this

group of JOF patients were found to besimilar to those reported in the litera-

ture.4,23

According to the internal compo-nents of hard and soft tissue, tumours can present as radiolucent, mixed, opaque, and ground glass-like. There is a high-density

boundary between the lesions and thesurrounding normal bone. The imaging

characteristics are often associated withhistological types.

23JPOF usually resem-

bles ground glass and JTOF usually looks

like mixed

or

radiolucent

shadows.

Thisgroup of cases had similar features. Pa-thologies that need to be distinguished from JOF using imaging studies include

fibrous dysplasia, osseous dysplasia,odontoma, and ameloblastoma. Althoughfibrous dysplasia can resemble ground glass, it usually has unclear boundaries

and may involve multiple bones. Osseousdysplasia usually presents as calcificationin the space between the roots or as acotton-like calcification involving the bi-

lateral upper and lower jaws. Odontomaand ameloblastoma are also common inyounger patients, although odontoma usu-ally presents as a mass with mixed densi-

ties around the roots, with clear boundaries and visible non-erupted teethor shadows of teeth of varying sizes.Ameloblastoma usually presents as multi-

ple radiolucent regions with discrete, cor-ticated borders. Aneurysmal bone cystassociated with JOF is reported wide-ly,

3,4,10,24,25and this is more common in

young patients and shows levelled fluid under CT examination.

10In this study,

there were two cases of JTOF with aneu-rysmal bone cyst. These two patients were

372 Han et al.

Fig. 4. Imaging findings in juvenile ossifying fibroma (JOF): case 11. (A) Preoperative panoramic radiograph showing a bulging body in the right mandible. (B) Four years after mandibular segmental resection and iliac bone graft, the mandible is in good shape with noevidence

of

recurrence.

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10 years and 7 years old at onset, which isconsistent with findings in the literature.Conventional OF lesions usually have

limited regions and clear boundaries.Patients usually undergo surgical excisionof the tumour. Recurrence is rare and the prognosis is good. However, there is cur-

rently no consensus on the treatment planfor JOF. Clinical treatments can be divid-ed into conservative and radical treat-ments, and the histological subtype has

no effect on treatment options. Consider-ing the aggressive growth pattern and highrecurrence rate of JOF, some researchersadvocate local radical surgery to

completely remove as much of the in-volved tissue as possible while preservingthe important surrounding structures. Nev-ertheless, excessive removal of the sur-

rounding nor mal bone tissue is notrecommended.

4,13,14Conservative treat-

ments including curettage, enucleation,and partial resection, aim to limit facial

deformity and dysfunction and preservegrowth and development, a normal appearance, and chewing and nerve func-tions in young patients.

12,15,16When

aggressive growth is obvious, which ismarked by rapid growth, cortical thinningor perforation, and the displacement of

teeth or root resorption, the patient should undergo complete resection.

12

In a recent study, researchers found thatthe simultaneous amplification of MDM2

(E3 ubiquitin-protein ligase gene) and RASAL1 (RAS protein activator like 1gene) was significantly higher in juvenileossifying fibromas compared with non-

juvenile ossifying fibromas. Moreover,among the nine cases of JOF withMDM2 and RASAL1 amplification, threedemonstrated local invasiveness or rapid

growth and four were recurrent. This ab-normality is not only a potential molecular diagnostic marker, but may also be indic-ative of aggressive forms of the disease

with a higher risk of recurrence,26and

therefore may indicate a more radicaltreatment plan.As JOF patients are relatively young,

clinicians should aim to maintain or re-store the patient’s appearance during treat-ment to reduce the impact on their growthand development. Individualized treat-

ment plans were developed for each pa-tient in the present study, after takingvarious factors into account. These factors

included the site of the lesion, involve-ment of the surrounding vital tissue, pa-tient age, growth rate, and parental choice.Of the 15 patients, nine initially underwent

conservative treatment and six received local radical surgery.In cases of large or rapidly growing

lesions, among others, complete resec-

tion should be chosen as the initial sur-gery. Additionally, due to the anatomicalstructure, maxillary lesions often involvethe nose, eyes, skull, and other tissues;

this makes complete resection difficult.Meanwhile, with relatively less impor-tant structures around mandibular lesions, segmental resection is not al-

ways necessary. Take case 3 for exam- ple: the lesion had a limited range, therewere clear boundaries between the lesionand the surrounding normal bone, and

the jawbone cortex had continuousedges; in this case enucleation of thetumour achieved a good prognosis(Fig. 7).


Fig.

5.

Imaging

findings

in

juvenile

ossifying

fibroma

(JOF):

case

13.

(A)

Preoperative

panoramic

radiograph

showing

a

transparent

shadow

in

theright condylar region, with clear boundaries. (B) Preoperative coronal CT showing shadows of mixed densities in the right condylar region. (C) Sixmonths after condylar tumour resection and cartilage repair, the shape of a metal plate is partially seen, and there is no evidence of recurrence. (D)Postoperative CT reconstruction showing good recovery of jaw shape.

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According to reports published in theliterature, the recurrence r ate after surgery

is approximately 30–58%.1,3,9–11

The totalrecurrence rate calculated from the presentdata is 40% (6/15), with the rate after conservative treatment being high at

66.7% (6/9) and the rate following radicalsurgery being zero. Since malignancieshave not been reported, these neoplasmscan safely be left when they are in a stable

state. In this study, three patients werealive with the tumour at the end of fol-low-up, and the tumour did not showobvious enlargement.

Defect reconstruction can be carried out at the time of excision 13,27–29or in a

second-stage procedure.30

There arereports of no repair or of immediaterepair using a reconstruction plate torestore the appearance after resection

of JOF.18,31

In this study, a total of nine patients underwent immediate recon-struction after resection. Based on thesite and size of the defect, three methods

of restoration were used, includingvascularized fibula flap transplantation(five cases), free iliac crest graft(three cases), and costal carti lage

transplantation to repair the condylar region (one case).

According to a report by Johnson et al.,aggressive growth characteristics of JOFlesions are mainly observed in the maxil-la.

3The anatomy of the maxilla prevents

the tumours at this site from being re-moved easily and completely, resultingin a high rate of relapse and difficultieswith reconstruction. In this study, among

patients who had lesions in the maxilla,only one (case 8) had single-side maxillaresection and fibula flap transplantation.The remaining eight patients who

374 Han et al.

Fig.

6 .

Imaging

findings

in

juvenile

ossifying

fibroma

(JOF):

case

8.

(A)

The

mandibular

lesion

relapsed

after

curettage.

Panoramic

radiographshowing a mixed shadow containing incomplete permanent crowns. (B) The lesion expanded 7 months after a second curettage. (C) Sagittal CTshowing transparent shadows with mixed densities. (D) Axial CT showing significant bulging in the lingual mandibular cheek. (E) CTreconstruction

revealing

severe

bone

destruction

and

cortical

discontinuity.

(F)

Two

years

and

1

month

after

mandibular

segment

resection

and fibula flap transplantation, there was no evidence of recurrence.

8/19/2019 Pi is 090150271501468 x

8/9

underwent reconstruction had mandibular defects. At the end of follow-up, all

patients with maxillofacial reconstructionhad recovered their appearance and therewere no signs of recurrence. Therefore, it

is speculated

that

reconstruction

can

be performed concurrently with preservingthe safety margins of the excision. Al-though there has been no report of malig-

nant transformation, the physician should be more cautious when choosing the tim-ing of r econstruction for rapidly growinglesions.

17

In summary, JOF of the jaw is a type of uncommon benign fibro-osseous lesion. IntheChinese population, JOF is more com-monly seen in females than in males and

may occur in children or adolescents. JOFhas two histological subtypes, which areJPOF and JTOF; JTOF is more common inthe jaw. Its imaging characteristics include

a radiolucent or mixed density appearancemarked by clear boundaries. The diagno-sis requires consideration of a combina-tion of factors such as age, growth pattern,

imaging features, and pathology. Al-though JOF has aggressive characteristicsand a high recurrence rate (40%, 6/15),malignancies have not been reported.

Therefore, initial conservative surgicaltreatment is recommended, but a radicalapproach is warranted for lesions that behave destructively, that present rapid

growth, where there is pain and displace-ment of teeth, and for lesions with one or

more recurrence. In addition, as the recur-rence rate following conservative treat-ment is high at up to 66.7% (6/9), long-

term

follow-up

and

vigilance

is

indicated.

Funding

This

work

was

supported

by

researchgrants

from

Shanghai

Jiao

Tong

Universi-

ty Cross Research Fund for Medical and Science (YG2012MS42), the Science and Technology

Commission

of

Shanghai

Mu-nicipality

(15411950300),

and

the

Shang-

hai Natural Science Foundation of China(13ZR1457100).

Competing interests

None.

Ethical

approval

Due to the retrospective nature of thisstudy, it was granted an exemption inwriting

by

the

Institutional

Review

Board of

the

Ninth

People’s

Hospital.

Patient

consent

Not required.

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Fig. 7 . Panoramic radiographs of juvenile ossifying fibroma (JOF): case 3. (A) Before surgery,JOF presented

as

a

single

transparent

shadow

in

the

right

mandible.

There

were

spots

of

high-density shapes. The boundaries were clear. The mandibular cortex had continuous edges. Theadjacent roots were displaced. (B) Two years after removal of the tumour, bone had formed atthe lesion site. There was no evidence of recurrence.

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