Ameloblastic Fibro-odontoma of Mandible

JDSOR
10.5005/jp-journals-10039-1023
Ameloblastic
Fibro-odontoma of Mandible
CASE REPORT
Ameloblastic Fibro-odontoma of Mandible
1
Renuka Gupta, 2Madhusudan Astekar, 3Rajesh Kumar Chittlangia
ABSTRACT
The ameloblastic fibro-odontoma is a rare mixed odontogenic
tumor. The ameloblastic fibro-odontoma is a well-circumscribed,
painless, slow-growing, and expanding tumor with no propensity
for bony invasion. Ameloblastic fibro-odontoma is often asymptomatic and usually detected as a result of failure of tooth eruption.
It occurs predominantly in children and young adults with no
sex predilection and present mostly in posterior segment of the
mandible. Many times it presents as a painless swelling, which is
the most common clinical sign. Radiologically, ameloblastic fibroodontoma shows a circumscribed radiolucency, which contains
radiopaque foci of various sizes and shapes. Here we present
a case of ameloblastic fibro­-odontoma in an 18-year-old male
patient associated with a hard painless swelling associated with
moderate facial asymmetry in the right mandibular region. On
histopathological analysis, all the classic features were noted
and diagnosis of an ameloblastic fibro-odontoma was made
without any obscurity. Diagnosis of ameloblastic fibro-odontoma
remains a challenge for oral pathologists. There are many
lesions, e.g. ameloblastic fibro-odontoma, odontoameloblastoma immature complex odontoma, calcifying epithelial odonto­
genic tumor and calcifying odontogenic cyst, which mimic
ameloblastic fibroodontoma clinically and histopathologically.
These conditions must be ruled out before making a definitive
diagnosis of ameloblastic fibro-odontoma.
Keywords: Diagnosis, Immature complex odontoma, Mixed
odontogenic tumor, Odonto-ameloblastoma.
How to cite this article: Gupta R, Astekar M, Chittlangia RK.
Ameloblastic Fibro-odontoma of Mandible. J Dent Sci Oral
Rehab 2014;5(2):103-106.
Source of support: Nil
Conflict of interest: None
INTRODUCTION
Ameloblastic fibro-odontoma (AFO) is a benign, slowgrowing, expansile epithelial odontogenic tumor with odonto­­
genic mesenchyme. Neivelle, et al described this entity to be
a combination of an ameloblastic fibroma and developing
complex odontome and approximately 80% lesions are
1
Postgraduate Student, 2Professor and Head, 3Senior Consultant
1,2
Department of Oral Pathology and Microbiology, Institute of
Dental Sciences, Bareilly, Uttar Pradesh, India
3
Department of Oncology, Keshlata Cancer Hospital, Bareilly
Uttar Pradesh, India
Corresponding Author: Madhusudan Astekar, Professor and
Head, Department of Oral Pathology and Microbiology, Institute
of Dental Sciences, Bareilly, Uttar Pradesh, India, Phone: 07599247899, e-mail: madhu.tanu@gmail.com
associated with an unerupted tooth. It may inhibit tooth
eruption or displace involved teeth, although teeth in the
affected area are vital.1-4
Radiographically, the lesion presents with a well-circum­
scribed, unilocular or multilocular radiolucent area containing various amounts of radiopaque material of irregular
size and form.1,4-6 The large areas of calcification make it
impossible to radiographically differentiate from complex
odontoma. The lesions are usually diagnosed during the first
and second decades of life. It occurs with equal frequency
in the maxilla and the mandible and with equal frequency
in males and females.1,6-8 Histopathologically, the AFO is
characterized by islands, strands and cords of odontogenic
epithelium immersed in embryonic connective tissue that
mimics primitive dental pulp. Formation of osteodentin
and enamel is also observed microscopically.9 Although,
amelo­blastic fibro-odontoma is a benign lesion, it is deve­
lo­ped at a very early age, with rapid growth and destruction
of cortical bone.10 Histologically, the features of AFO are
indistin­guishable from the odontoameloblastoma, immature complex odontoma, calcifying epithelial odontogenic
tumor and calcifying odontogenic cyst. This report describes
an ameloblastic fibro-odontoma in an 18-year-old boy with
an emphasis on its clinical features, radiographic features,
histopathology, differential diagnoses and manage­ment.
CASE REPORT
An 18-year-old boy was referred to the Dental OPD at the
Insti­tute of Dental Sciences, Bareilly, complaining about a
swelling in the right mandibular region. The medical, social
and family histories were unremarkable and there was no
per­sonal habits related to oral cavity. Extraoral examination showed moderate facial asymmetry on the right side.
On pal­pation, a hard painless swelling was observed in the
right mandibular body. Intraoral examination revealed the
lesion was a painless, hard swelling, normal colored mucosa,
increase in the volume of alveolar ridge and no defi­nition of
vesti­bular fold extending from distal aspect of permanent
right mandibular first premolar till the retromolar pad area
(Fig. 1).
Panoramic radiography exhibited large and muliple
radiopacities enveloped by the radiolucent zone extending
from the region of the right permanent first premolar region
up to the anterior border of the ramus of the mandible with
the presence of an impacted right lower third molar. The
lesion contained scattered foci of calcified material coronal
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Renuka Gupta et al
Fig. 1: Hard swelling of alveolar ridge extending from distal
aspect of #44 till the retromolar pad area
Fig. 2: Panoramic radiograph showing multiple large radiopaque lesion
enveloped by the radiolucent zone extending from #44 region to the
anterior border of the ramus of the mandible. Impacted #48 is also seen
Figs 3A to D: The photomicrograph under hematoxylin and eosin stained sections showing: (A) Small odontogenic epithelial islands,
strands and cords interspersed in moderately cellular hemorrhaghic connective tissue stroma (×100), (B) Delicate stroma resembling
ectomesenchyme along with large calcified areas resembling dentinoid and enamel matrix (×100) and (C and D) Strands, cords and
islands of odontogenic epithelium with delicate connective tissue stroma (×400)
to the impacted tooth (Fig. 2). Considering the clinical and
radiographic findings, a provisional clinical diagnosis of
benign odontogenic neoplasm with hard tissue formation
was made. The provisional clinical diagnosis of complex
odontome was made. Ameloblastic fibro-odontoma,
calci­fying epithelial odontogenic tumor and calcifying
odontogenic cyst were included in differential diagnoses.
Excisional biopsy was performed, and the mass, inclu­
ding the third molar, was submitted for histopathologic
diagnosis. On histopathological analysis, the hematoxylin
and eosin-stained sections revealed characteristics of both
104
ameloblastic fibroma and odontoma. Microscopic features
show odontogenic epithelium arranged in islands, strands
and cords interspersed in moderately cellular connective
tissue stroma with predominantly spindle-shaped fibroblasts
along with some hemorrhaghic areas (Fig. 3A). In some
areas, the stroma was delicate resembling ectomesenchyme.
High-power microscopy revealed epithelial cells producing
large hematoxyphilic calcified areas resembling enamel
matrix and dentinoid material (Fig. 3B). Odontogenic epithelium arranged in small island, strands and cords interspersed in under high power (Figs 3C and D). No evidence
JDSOR
Ameloblastic Fibro-odontoma of Mandible
of malignancy, such as nuclear pleomorphism was observed,
and based on clinicopathologic correlation, the diagnosis of
‘Ameloblastic fibro-odontoma’ was made.
DISCUSSION
According to WHO classification of odontogenic tumors,
ameloblastic fibro-odontoma has traditionally been classi­fied
under odontogenic epithelium with odontogenic ectomesen­
chyme, with or without hard tissue formation. The term ‘epithelial odontogenic tumor with odontogenic mesen­chyme’ is
becoming more widely accepted these days and avoids poten­
tial controversy over the nature of the neoplasia. The term
‘ameloblastic fibro-odontoma’ represents a histologic combi­
nation of ameloblastic fibroma and complex odontoma.1,8
There has been a lot of discussion in the literature regard­
ing its proper classification. One point of discussion is the
discri­mination between neoplasm and hamartoma. Philipsen
et al11 indicated that the amelo­blastic fibro-odontoma has a
hamartomatous character but, in contrast, the ameloblastic
fibroma has a neoplastic nature. Most authors now agree that
ameloblastic fibro-odontoma is a separate entity but it can
be histologically indistinguishable from immature complex
odontoma. The relative arrangement of the soft tissues and
the stage of development of the involved tooth are the useful
criteria for diagnosis.11
The term ‘ameloblastic fibro-odontoma’ appears in the
World Health Organization (WHO) classification of odonto­
genic tumors, whereas ameloblastic odontoma is called
odonto-ameloblastoma in the WHO classification.12,13
In fact, some cases reported in the literature are truly
neoplastic and have showed a malignant differentiation.
Immune staining with anti-amelogenin sera proved that
tumor epithelium and mesenchyme can potentially mimic
the full spectrum of phenotypic changes, and the cellular and
molecular events that regulate normal odontogenesis most
likely operate to a certain extent in the pathogenesis and
differentiation of odontogenic tumors.9 Controversy exists
regarding the histogenesis of the mixed odontogenic tumors.
Cahn and Blum postulated that ameloblastic fibroma is the
histologically least differentiated tumor and develops first
into a moderately differentiated form, ameloblastic fibroodontoma, and eventually into complex odontoma. However,
the concept that these lesions represent a continuum of
differentiation is not widely accepted, and others feel that
they are separate pathologic entities. Most now agree that
ameloblastic fibro-odontoma exists as a distinct entity, but
it can be histologically indistinguishable from immature
complex odontoma. 14
Ameloblastic fibro-odontoma is relatively rare. The preva­
lence among oral biopsies is about 1% and the fre­quency of
ameloblastic fibro-odontoma among odonto­genic tumors
is reported as 1 to 3%. Daley12 and others investi­gated the
relative incidence of odontogenic tumors in the Canadian
population and found that 3.06% of all odontogenic tumors
were ameloblastic fibro-odontomas. Ameloblastic fibroodontoma usually occurs in people less than 20 years old,
and age is thus an important characteristic in the differential
diagnosis.2-8 Hooker reported the mean age of patients as
11.5 years (6 months-39 years).8 In presently described case,
in which the patient was 18 years old, agrees with the above
observations regarding age range as described by different
authors. There is no difference in prevalence between the
sexes.7,8 In the present case, the patient was a boy.
Ameloblastic fibro-odontoma is usually found in the
molar area. The distribution is roughly equal between the
maxilla and mandible.7,8 However, in the present case, the
lesion was present with respect to right posterior mandible.
The two most common presenting complaints are swelling and failure of tooth eruption. The lesion may dis­place
the erupted teeth, but other symptoms, such as pain and
paresthesia, are uncommon. Asymptomatic cases are usually
discovered incidentally on radiography. This lesion is generally considered a slow-growing central jaw tumor; however,
several exceptions to this pattern have been reported.1 Occa­
sionally, the tumor exhibits marked swelling, which results
in facial disfigurement.9 Finally, an AFO sometimes inhibits
tooth eruption.15 In the present case also, the significant facial
disfigurement was observed because of swelling, representing
its sprawling nature.
Radiography usually shows a well-defined radiolucent
area containing various amounts of radiopaque material of
irregular size and form.16 The ratio of radiopaque to radiolucent areas differs from one lesion to another; sometimes
the mineralized element in the tumor predominates and the
lesion may resemble an odontoma.17 Some of the lesions are
relatively small when first detected, measuring 1 to 2 cm in
diameter, whereas others may be exceedingly large, invol­
ving a considerable portion of the body of the mandible or
maxilla.18 In the present case, large and muliple radiopacities
enveloped by the radiolucent zone extending from the region
of the right permanent first premolar region up to the anterior
border of the ramus of the mandible with the presence of an
impacted right lower third molar, which is consistent with
the findings of other authors.
The other lesions which are showing mixed radiolucent
and radiopaque patterns are calcifying epithelial odonto­
genic tumor, calcifying odontogenic cyst, immature complex
odontoma and possibly adenomatoid odontogenic tumor.19
Histopathologically, the relative arrangement of the
soft tissues and the stage of development of the involved
tooth are useful criteria for diagnosis.1 The tumor mass is
surrounded by a fibrous capsule and is composed predomi-
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Renuka Gupta et al
nantly of a fibroblastic connective tissue matrix containing
strands of odontogenic epithelium and immature tooth
structures, including enamel and dentin. The connective
tissue is moderately cellular with spindle-shaped fibroblasts.
No evidence of malignancy is found.1 As mentioned above,
the diagnosis of present case was also made, considering the
same histopathologic criteria.
The histological characteristics of AFO cannot be distinguished from odontoma, and consequently, some authors
believe that ameloblastic fibro-odontoma is an immature
complex odontoma. The large amount of calcifying tissue
present in the lesion may speak in favor of the theory that
AFO is an early stage of odontoma.19
In the same way, no ultrastructural differences were
observed between AFO and ameloblastic fibroma but, histologically, thin strands or cords of epithelium that resembles
dental lamina and cap and bell stage of early odontogenesis
can be seen in ameloblastic fibroma. Ameloblastic fibroodontoma can be differentiated from calcifying odontogenic
cyst on the basis that it is a well-circumscribed, solid or
cystic lesion derived from odontogenic epithelium that
micro­scopically resembles ameloblastoma but differs by
containing ghost cells and spherical calcifications. Calcifying epithelial odontogenic tumor microscopically consists of
sheets and strands of polyhedral epithelial cells, homogenous
eosinophilic deposits that stain positive for amyloid, and
spherical calcifications which differentiates it from ameloblastic fibro-odontoma. In odontoameloblastoma, there is
presence of sheets of typical ameloblastoma of recognized
types, usually basal cell, follicular or plexiform which diffe­
rentiates it from ameloblastic fibro-odontoma and tumor
cells recapitulate stratum intermedium layer of early bell
stage of odontogenesis.20
The recommended treatment for ameloblastic fibroodontoma is conservative surgery with enucleation because it
is well encapsulated benign tumor and there is little tendency
to local invasion. When the lesion includes an unerupted
tooth, the tooth should be removed with the mass. There
is very little potential for recurrence.6 Malignant trans­
formation of ameloblastic fibro-odontoma is rare, and its
exact rate is not known. Howell and Burkes reported two
cases of ameloblastic fibro-odontoma that showed malignant
trans­formation to ameloblastic fibrosarcoma.19 The present
case was treated with conservative surgery with enucleation
along with removal of impacted third molar tooth. After a
follow-up of 9 months, no recurrence was observed and the
healing was without any complications.
In conclusion, the case reported here represents an
amelo­blastic fibro-odontoma causing significant facial
asym­metry with jaw expansion. Diagnosis of ameloblastic
fibro-odontoma remains a challenge for oral pathologists.
106
There are many lesions which mimic ameloblastic fibroodontoma clinically and histopathologically. These conditions must be ruled out before making a definitive diagnosis
of ameloblastic fibro-odontoma.
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