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Paper text:
ameloblastic fibro - odontoma ( afo ) is a benign , slow growing , expansile epithelial odontogenic tumor with odontogenic mesenchyme .
it may inhibit tooth eruption or displace involved teeth although teeth in the affected area are vital [ 13 ] .
radiography shows a well - defined , radiolucent area containing various amounts of radiopaque material of irregular size and form [ 4 , 5 ] .
the lesions are usually diagnosed during the first and second decades of life [ 46 ] .
it occurs with equal frequency in the maxilla and the mandible and with equal frequency in males and females .  
microscopically , the lesion is composed of strands , cords , and islands of odontogenic epithelium embedded in a cell - rich primitive ectomesenchyme , resembling the dental papilla .
many authors reported that afo is not aggressive and can be treated adequately through a surgical curettage to the lesion without removal of the adjacent teeth [ 1 , 4 , 5 , 7 , 8 ] .
an 11-year - old girl presented to our department on referral from another dentist to have a second opinion about a lesion involving the left mandible .
she had radiographic examinations , including panoramic , helical , and cone - beam computed tomography .
these examinations were accompanied by a presumptive radiographic differential diagnosis of  odontoameloblastoma  : complex odontoma and afo .  
the medical , social and family histories were unremarkable , as were the results of a review of systems and a physical examination .
the clinical examination did not display any sign of pain or swelling in the left mandible .
the initial panoramic radiography revealed a well - defined radiolucent region , which contained an irregular radiopaque mass 3  cm in diameter .
this lesion occupied a zone from the lower left second molar area to the left ramus .
helical and cone - beam computed tomography showed an expansile well - circumscribed lesion containing at the interior a calcified mass compatible with odontogenic tissue ( figures 2 and 3 ) .   considering the clinical and radiographic examinations , our presumptive diagnosis was complex odontoma .
the patient underwent enucleation of the lesion and careful curettage of the surgical cavity under general anesthesia .
the surgical specimen was fixed in neutral buffered 10% formalin and subjected to pathological analysis .
light microscopic examination of sections stained with hematoxylin and eosin revealed strands and islands of odontogenic epithelium showing peripheral palisading and loosely arranged central cells , identical to stellate reticulum , embedded in a myxoid cell - rich stroma resembling the dental papilla ( figure 4 ) .
in the present case , the patient presented to our department with previous examinations , including panoramic , helical and cone - beam computed tomography .
while these radiographic examintions were given a presumptive diagnosis of odontoameloblastoma by the examinaing radiologists , we believed that the findings were more common in this region .
odontoameloblastoma , also known as ameloblastic odontoma , has a more aggressive behavior , similar to an ameloblastoma rather than an odontoma .  
afo is a benign tumor that exhibits the same benign biologic behavior as that of ameloblastic fibroma , showing inductive changes that lead to the formation of both dentin and enamel .
conversely , the term  odontoameloblastoma  ( or  ameloblastic odontoma  ) refers to tumors representing a histological combination of ameloblastoma and complex odontoma , which behave in the invasive manner of classic ameloblastoma . according to the revised world health organization ( who ) classification , ameloblastic fibroma and afo
cahn and blum   postulated that ameloblastic fibroma ( the histologically least differentiated tumor ) develops first into a moderately differentiated form , following afo and eventually into a complex odontoma.however , the concept that these lesions represent a continuum of differentiation is not widely accepted , with other researchers suggesting that they are separate pathologic entities [ 1215 ] . in some studies , the term afo represents a histological combination of ameloblastic fibroma and complex odontoma [ 12 , 16 ] .
the majority now agrees that afo exists as a distinct entity , but it can be histologically indistinguishable from immature complex odontoma . the arrangement of the soft tissues and the development stage of the involved tooth are useful criteria for diagnosis .
despite numerous efforts , however , there is still considerable confusion concerning the nature of these lesions .  
afo is relatively rare , with the prevalence among oral biopsies being about 1%   and its frequency among odontogenic tumors being reported at 1% to 3% [ 3 , 18 ] .
this lesion usually occurs in people less than 20 years old , and age is thus an important characteristic in the differential diagnosis .
this lesion is usually found in the molar area [ 6 , 12 ] , and the distribution is roughly equal between the maxilla and mandible [ 6 , 12 ] .  
many authors reported that afo can be treated adequately through a surgical curettage without removal of the adjacent teeth [ 1 , 4 , 5 , 7 , 8 ] .
as noted in the literature , not all lesions previously classified as afo are , in fact , aggressive lesions .
if there is a recurrence accompanied by a change of the histological pattern toward a more unorganized fibrous stroma with displacement of the epithelial component , then more extensive treatment procedures appear to be indicated .
long - term follow up with short intervals should be maintained in the management of afo .
an 11-year - old girl presented to our department to have a second opinion regarding a lesion involving her left mandible . 
 she had previously undergone several radiographic exams including panoramic , helical , and cone - beam computed tomography . 
 radiographic examinations revealed a well - defined radiolucent region , which contained an irregular radiopaque mass of 3  cm in diameter , localized to the left angle of the mandible . 
 our presumptive diagnosis was complex odontoma . 
 excisional biopsy was performed , and microscopic features showed strands and islands of odontogenic epithelium showing peripheral palisading and loosely arranged central cells , identical to stellate reticulum , embedded in a myxoid cell - rich stroma resembling the dental papilla . 
 dentin and enamel were also presented . 
 the diagnosis was ameloblastic fibro - odontoma , which is a rare mixed odontogenic tumor , derived from epithelial and ectomesenchymal elements that form the dental tissues .