|Year : 2019 | Volume
| Issue : 3 | Page : 715-718
Ameloblastic fibro-odontoma in a 14 year old girl: A case report
A Jacob Prakash Rao1, Madhusudhan Reddy2, Vijaya Lakshmi Mahanthi1, K Venkata Chalapathi1
1 Department of Oral Pathology and Microbiology, Lenora Institute of Dental Sciences, Rajahmundry, East Godavari, Andhra Pradesh, India
2 Department of Oral Pathology and Microbiology, Army College of Dental Sciences, Jai Jawahar Nagar, CRPF-Road, Chennapur, Secundrabad-87, Telangana, India
|Date of Web Publication||29-May-2019|
Dr. Madhusudhan Reddy
Department of Oral Pathology and Microbiology, Army College of Dental Sciences, Jai Jawahar nagar, CRPF-Road, Chennapur, Secundrabad-87, Telangana
Source of Support: None, Conflict of Interest: None
Ameloblastic fibro-odontoma (AFO) is a benign, epithelial odontogenic tumor with odontogenic mesenchyme having the histologic characteristics of both ameloblastic fibroma and complex odontoma. This report describes the case of a 14-year-old girl with AFO on the right posterior mandibular region that mimics complex odontoma on incisional biopsy due to the presence of atypical dentin- and cementum-like areas. On histological examination, sections of excisional biopsy showed odontogenic epithelial islands with embryonic connective tissue and decalcified sections showed atypical dentin with dentinal tubules and islands of cementum. These features led to the diagnosis of AFO.
Keywords: Ameloblastic fibro-odontoma, complex odontoma, mixed odontogenic tumor
|How to cite this article:|
Rao A J, Reddy M, Mahanthi VL, Chalapathi K V. Ameloblastic fibro-odontoma in a 14 year old girl: A case report. J Can Res Ther 2019;15:715-8
| > Introduction|| |
Ameloblastic fibro-odontoma (AFO) is a benign, slow-growing, uncommon mixed odontogenic tumor. The World Health Organization (WHO) defined it as “a neoplasm composed of proliferating odontogenic epithelium in a cellular ectomesenchymal tissue with varying degrees of inductive changes and dental hard tissue formation.” AFO was first described as a separate entity in 1972 by Hooker, constituting approximately 1%–3% of odontogenic tumors., The frequently affected sites are posterior mandible and posterior maxilla. AFO usually presents as a painless swelling and is often associated with delayed tooth eruption. The lesion has biologic behavior and histologic feature similar to ameloblastic fibroma (AF), but in AFO, differentiation process of one or more cellular foci continues, leading to the formation of enamel and dentin.
| > Case Report|| |
A 14-year-old girl presented to a private dental clinic, on April 2015, with a complaint of swelling in the right retromolar area for 1 week. Medical history was noncontributory. The patient is healthy with no systemic diseases. General physical examination showed no abnormality and no history of trauma was mentioned. No gross facial asymmetry was observed. Intraoral examination revealed swelling on the right posterior mandible distal to tooth 46. The swelling was nontender, firm in consistency, obliterating the buccal vestibule, and there was slight restricted mouth opening. Apparent clinical absence of the right mandibular second molar (47) was noted.
Orthopantomography view revealed a radiopaque mass in the right mandibular third molar area with a well-defined sclerotic border and a thin radiolucent rim surrounding the irregular mass of calcified tissue with varying degrees of radiopacity [Figure 1]. This lesion occupied a zone from the lower right second molar area to the right ramus and the coronoid process. The mandibular third molar was not present. Correlating with clinical and radiologic presentations, a provisional diagnosis of a complex odontoma or AFO was made. Incisional biopsy was made under local anesthesia and submitted for histopathological examination. Microscopic examination revealed connective tissue cores resembling pulp surrounded by atypical dentin with sparse dentinal tubules in longitudinal and cross sections. Few areas showed islands of hematoxyphilic substance resembling cementum and areas of bone with osteolytic lacunae. Focal areas of odontoblast-like cells [Figure 2] were observed. These histopathological features were suggestive of complex odontoma.
|Figure 1: Orthopantomogram revealing radiopaque mass in the right mandibular second molar area|
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After a final histological diagnosis of complex odontoma, the patient underwent enucleation of the lesion along with the fibrous capsule under general anesthesia on May 2015. The areas were curetted well and the lesional space was packed with bone graft and betadine-soaked gauze. The specimen was fixed in neutral-buffered 10% formalin and subjected to histopathological analysis [Figure 3].
Histopathological examination of the hematoxylin and eosin-stained soft-tissue section revealed primitive odontogenic epithelium resembling dental lamina, proliferating into the underlying mesenchymal tissue [Figure 4]. High-power view revealed odontogenic epithelial islands with peripheral tall columnar cells showing reverse polarity of nucleus and central loosely arranged cells simulating stellate reticulum [Figure 5]. Adjacent connective tissue (ectomesenchymal tissue) resembled dental papilla. Decalcified section revealed connective tissue cores resembling pulp surrounded by atypical dentin [Figure 6], with numerous dentinal tubules in longitudinal and cross sections [Figure 7]. Few islands of hematoxyphilic areas resembling cementum were seen. A final diagnosis of intraosseous AFO was made. The described case meets clinical, radiographic, and histological criteria for the diagnosis of AFO. The patient was followed up postoperatively for about 6 months and no sign of recurrence was observed. Healing of the soft tissue was uneventful and complete bone healing was observed in postoperative panoramic radiography.
|Figure 4: Photomicrograph showing primitive odontogenic epithelium resembling dental lamina (arrow), proliferating into the underlying mesenchymal tissue (H and E, ×100)|
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|Figure 5: Photomicrograph showing numerous epithelial islands with peripheral tall columnar cells (red arrow) showing reverse polarity of nucleus simulating ameloblasts and central loosely arranged cells simulating stellate reticulum (black arrow) (H and E, ×400)|
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|Figure 6: Photomicrograph of decalcified section showing connective tissue cores resembling pulp (black arrow) surrounded by atypical dentin (red arrow) and cementum (blue arrow) (H and E, ×40)|
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|Figure 7: Photomicrograph of decalcified section revealing atypical dentin with numerous dentinal tubules (arrow) (H and E, ×100)|
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| > Discussion|| |
According to the recent WHO classification of odontogenic tumors published in 2005, AFO belongs to the group of lesions with odontogenic epithelium with odontogenic ectomesenchyme, with or without hard-tissue formation. “Ameloblastic fibro odontoma is an uncommon mixed odontogenic tumor similar to ameloblastic fibroma, but showing inductive changes that lead to the formation of dentin and enamel.” It has been described using a variety of terms such as immature ameloblastic odontoma. AFO is seldom reported in literature due to the rarity of incidence and accounting for 1%–3% of all odontogenic tumors. Three epidemiological studies till date on AFO revealed that the total number of published cases were 114, 108, and 215, respectively.
The exact histogenesis of the mixed odontogenic tumors is controversial. Cahn and Blum postulated that AF, a least differentiated tumor, initially transforms into a moderately differentiated form, AFO, and finally into complex odontoma. However, the concept of a continuum of differentiation is not widely accepted.
Some authors suggested that this mixed odontogenic lesion exists as a distinct entity, but it can be histologically indistinguishable from developing immature complex odontoma.
AFO usually occurs in young patients, with a mean age of 11.5 years  and a male-to-female ratio of 1.4/1. AFO is usually found in the molar area with a significant tendency of mandibular region. Many studies suggested that the lesion is found equally in the posterior mandible and maxilla.,,,
Clinically, it presents as a painless, slow-growing tumor, often associated with swelling and unerupted tooth as in the present case. However, pain and paresthesia are uncommon, and it is incidentally discovered during routine radiography. Radiographic imaging shows a well-defined radiolucency containing varying amounts of radiopaque material of irregular size and form. Small lesions may appear as enlarged follicles with only one or two small, discrete radiopacities. Larger lesions show extensive calcified internal structure. In some cases, these small calcifications have a round shape with a radiopaque enamel-like margin, giving a shape similar to a small doughnut.
Histologically, the tumor is arranged in the form of islands, cords, and strands of odontogenic epithelium in a cellular stroma. The epithelium is characterized by peripheral tall columnar cells showing reverse polarity of nucleus and the center of the tumor shows loosely arranged cells simulating stellate reticulum present in a cell-rich dental papilla-like ectomesenchyme stroma. The epithelial component shares many features of ameloblastoma; however, the stroma is strikingly different. The presence of hard dental tissues such as enamel matrix and irregular dentin is the characteristic feature of AFO.
When AFO presents with a typical age, location, and radiographic pattern, diagnosis is usually obvious. Differential diagnosis of AFO includes immature complex odontomas, odontoameloblastomas, ameloblastic fibrodentinomas (AFDs), and AF.
Tumors such as AFO, though very rare, are difficult to distinguish from complex odontoma. Presence of enamel-, dentin-, and cementum-like components in a haphazard pattern favors the diagnosis of a complex odontoma. Odontoameloblastoma differs from AFO by virtue of its epithelial component typical of ameloblastoma and the cellular fibrous stroma with myxoid tissue adjacent to the dental calcified tissues. Based on histologic differentiation, AFD is defined as a stage between AF and AFO. The histomorphological appearance of AFO is similar to that of AFD. Subtle differences such as enamel matrix production and osteodentin or dentin-like deposits favor the diagnosis of AFO. In contrast to AFO, AF has no signs of dental hard-tissue formation and the potential for recurrence and malignancy exists.
The differential diagnosis of AFO should also include lesions with mixed radiographic patterns, such as calcifying odontogenic cyst, calcifying epithelial odontogenic tumor, and possibly adenomatoid odontogenic tumor.
Treatment of AFO is generally enucleation with concurrent removal of associated unerupted tooth. As the tumor is well encapsulated, there is little tendency to local invasion.,, There is very little potential for recurrence. Malignant transformation is rare, and hence long-term follow-up is recommended.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]