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 Table of Contents  
Year : 2014  |  Volume : 26  |  Issue : 3  |  Page : 310-314

Ameloblastic fibro-odontoma differentiating into odontoma: An old concept revised

Department of Oral Medicine, Diagnosis and Radiology, Government Dental College and Hospital, Mumbai, Maharashtra, India

Date of Submission04-Aug-2014
Date of Acceptance12-Nov-2014
Date of Web Publication19-Nov-2014

Correspondence Address:
Ajas A Gogri
Room No. 23, Department of Oral Medicine, Diagnosis and Radiology, Government Dental College and Hospital, Mumbai - 400 001, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0972-1363.145016

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Ameloblastic fibro-odontoma (AFO) is a benign mixed tumor of odontogenic origin. It generally occurs in children and teenagers; however, cases occurring in the elderly have also been reported. Generally, the tumor is asymptomatic and is discovered accidently on a radiograph taken for an unerupted tooth, but examples of large tumors causing jaw swelling have been reported in literature. This article presents a case of AFO causing jaw expansion with pain and lymphadenopathy in a 17-year-old male. As the final diagnosis is always confirmed by histopathology, this case is a unique one diagnosed by clinical and radiographic findings as an odontoma and suggesting the differentiation of an AFO to odontoma.

Keywords: Ameloblastic fibro-odontoma, jaw expansion, mixed tumor, odontoma, unerupted tooth

How to cite this article:
Gogri AA, Kadam SG, Umarji HR, Jain PN. Ameloblastic fibro-odontoma differentiating into odontoma: An old concept revised . J Indian Acad Oral Med Radiol 2014;26:310-4

How to cite this URL:
Gogri AA, Kadam SG, Umarji HR, Jain PN. Ameloblastic fibro-odontoma differentiating into odontoma: An old concept revised . J Indian Acad Oral Med Radiol [serial online] 2014 [cited 2022 May 22];26:310-4. Available from: https://www.jiaomr.in/text.asp?2014/26/3/310/145016

   Introduction Top

The World Health Organization (WHO) defined ameloblastic fibro-odontoma (AFO) as a neoplasm composed of proliferating odontogenic epithelium embedded in a cellular ectomesenchymal tissue that resembles dental papilla, and with varying degrees of inductive change and dental hard tissue formation. [1] Ameloblastic fibro-odontoma is a relatively rare and slow-growing tumor. Among the odontogenic tumors, the incidence of AFO varies from 0.3 to 1.7%. [2] As reported by Regezi, Kerr, and Courtney, it represents 2% of all odontogenic tumors. In his study, Slootweg had concluded that AFO represents an immature complex odontoma. A recent study also suggests that AFOs are hamartomatous in nature, representing a stage that precedes the complex odontoma. [3] Radiographically, AFO shows a well-defined radiolucent area containing various amounts of radiopaque material. This article presents a case of AFO appearing radiographically as multiple radiopacities surrounded by radiolucent periphery, which led us to a presumptive diagnosis of composite odontoma with hybrid features of compound and complex types.

   Case Report Top

A 17-year-old male patient presented to us with the chief complaint of a painful, gradually enlarging swelling in the right mandibular posterior region since 1½ years. Patient gave a history of fever since many days and was unable to open the mouth due to secondary trismus. There was no history of paresthesia or anesthesia. Patient also gave a history of extraction of 47. On general examination, the patient appeared to have a good physique with average height. On extraoral examination, gross facial asymmetry could be seen due to a diffuse bony hard swelling on the right mandibular region. It extended from the corner of the mouth to the posterior border of the ramus and from the right submandibular region to a region just above the occlusal level. The swelling was tender on palpation, but overlying skin showed no signs of inflammation. Submandibular lymph nodes on the right side were enlarged and tender. Inferior border of the mandible was expanded when compared to the contralateral side [Figure 1]a, b. Intraoral examination of the patient was difficult due to the limited mouth opening. Sutures were seen in 47 region. Expansion of the buccal and lingual cortex was palpable intraorally. There was lingual displacement of 46 and the adjacent mucosa was normal [Figure 2].
Figure 1: (a) Front profile view showing gross facial asymmetry; (b) lateral profile view showing swelling extending from the corner of the mouth to the posterior border of the ramus

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Figure 2: Sutures visible in 47 region with lingually displaced 46

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Patient was subjected to radiological examination. The orthopantomograph (OPG) revealed a lesion in the right mandibular molar-ramus region, extending anteroposteriorly from 46 to 0.5 cm away from the posterior border of ramus and superoinferiorly from 1 cm below the sigmoid notch to the angle of the mandible. The center of the lesion showed an irregular, radiopaque mass which was surrounded by many small radiopaque structures on all sides. Some of these were circular in shape and a few appeared as miniature tooth-like structures (denticles). The entire radiopaque lesion was surrounded by a narrow radiolucent band with a smooth outer periphery. The lesion had displaced 48 at the angle of mandible [Figure 3]. The posteroanterior (PA) view of the mandible showed expansion of buccal and lingual cortices [Figure 4].
Figure 3: OPG showing multiple radiopaque structures in the right mandibular molar-ramus region

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Figure 4: PA mandible view showing buccal and lingual cortical expansion

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Cone-beam computed tomography (CBCT) of the patient showed the lesion measuring 47 mm × 37 mm × 46 mm (anteroposterior × mesiolingual × superoinferior) in its maximum dimensions. The denticle-like structures showed a density equivalent to enamel and dentin, as per the Hounsfield (HU) values shown in the software. The lesion had caused expansion, thinning, and perforation of the buccal and lingual cortices, along with perforation of the anterior border of ramus. Expansion and thinning of the inferior border of mandible was seen without perforation. Inferior alveolar canal was not traceable at the site of the lesion. Lingual displacement of 45 and 46 could be seen in 3D views. Displaced 48 showed crown portion and coronal one-third of the root portion, with missing middle and apical third of the root, either due to resorption or non-development [Figure 5]a-c and [Figure 6]a-c.

A provisional diagnosis of a benign tumor was considered based only on clinical findings. Radiographically, the appearance of radiopaque structures was indicative of an odontoma. The HU values of the calcified parts also indicated values close to enamel and dentin. Though odontomas are generally asymptomatic, cases of large odontomas causing jaw swelling have been reported in the literature. So, diagnosis of compound-complex odontoma consisting of central complex variety and the compound variety surrounding it was made based on the radiographic findings.The following differential diagnoses were considered:
Figure 5: (a) CBCT-axial view showing bucco-lingual expansion and perforation in the body and ramus region; (b) CBCT-sagittal view showing perforation of anterior border of ramus; (c) CBCT-coronal view showing perforation of superior cortex

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Figure 6: (a) 3D reconstructed view showing lingual displacement of 45 and 46; (b) 3D reconstructed view showing central complex odontoma surrounded by multiple small denticles with impacted 48; (c) 3D reconstructed view showing more buccal expansion than lingual

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  1. Calcifying epithelial odontogenic tumor (CEOT)- Molar-ramus area is the most common location for CEOT, but the calcifications seen in CEOT are less dense, diffuse, and irregular. This case showed more dense denticle-like structures, so CEOT was ruled out.
  2. AFO- Since the tumor was associated with unerupted 48, AFO of pericoronal variety could be considered. They are radiolucent tumors containing radiopaque foci; however, this case was primarily a radiopaque lesion.
  3. Ameloblastic odontoma- It is difficult to distinguish between odontoma and ameloblastic odontoma based on clinical and radiographic examinations, as both appear similar.
  4. Chronic osteomyelitis- Presence of fever and pain with lymphadenopathy supports it, but features such as sinus tract formation and pus drainage were not seen. Moreover, the appearance of denticle-like structures with a smooth outer periphery of this lesion excluded the possibility of osteomyelitis.

The patient was referred to a tertiary center for further management; hence, the histopathology picture could not be reproduced. But the patient reported back with the histopathology report after biopsy, which showed plump, short, spindle-shaped cells arranged in storiform and haphazard patterns. The cells were separated by abundant fibrous stroma. In a few areas, scattered cords of ameloblastic cells were seen with small ovoid nuclei. Areas of myxoid changes were seen. Few inflammatory cells and multinucleated giant cells were noted with calcific deposits and osseous islands. The overlying squamous epithelium showed mild acanthosis and hyperkeratosis. There was no mention about the odontoma component seen radiographically, probably due to the biopsy specimen being taken from the peripheral part of the lesion.

The histological diagnosis of ameloblastic fibroma was given, and correlating with the clinical and radiographic features, a final diagnosis of AFO was made. The lesion was completely excised in the same tertiary center.

   Discussion Top

In 2005, WHO classified AFO under the category of benign odontogenic tumors consisting of odontogenic epithelium and odontogenic ectomesenchyme with or without hard tissue formation. [1] Ameloblastic fibro-odontoma is a highly controversial lesion. It has been a matter of dispute whether ameloblastic fibroma, AFO, and complex and compound odontoma are different entities or they represent different stages of the same lesion. Cahn and Blum postulated that histologically, the least differentiated tumor, ameloblastic fibroma, develops into AFO (moderately differentiated form) and eventually into complex odontoma. [4] Eversole and colleagues postulated that the individual lesions are incapable of further differentiation. Slootweg compared all the three and concluded that ameloblastic fibroma is a true neoplasm and not a hamartoma. Considering the relationship of AFO and odontoma, he reported that the data on age, site, and sex were consistent with the concept that AFO represents an immature complex odontoma and concluded AFO to be a hamartomatous lesion. [5] Since cases have been reported in literature that show true neoplastic behavior and malignant transformation, not all cases of AFO should be considered hamartomatous.

In our case, the lesion had caused progressive swelling over a period of 1½ years, along with pain and lymphadenopathy. It showed ameloblastic fibroma type features histologically and appeared as odontoma radiographically. Thus, we conclude that it is a case of AFO showing differentiation into odontoma and also showing neoplastic behavior. We also conclude that different lesions are described under the same term AFO, some being hamartomatous in nature and some showing a neoplastic feature, some AFOs representing immature complex odontoma and some as a distinct entity.

Ameloblastic fibro-odontoma is generally seen in children. In his study of 26 cases, Hooker reported an age range of 0.5-39 years with a mean age of 11.5 years and only 2 cases above the age of 20 years. [6] In 1997, Philipsen et al. studied 86 cases of AFO in the literature and found only 1 case with an age of >20 years at the time of diagnosis. In a series of 50 cases reviewed by Slootweg in 1981, he reported a mean age of 8.1 years. [5] In this case, the patient was 17 years at the time of diagnosis.

Hooker reported a ratio of 3.3:1 in favor of males. [6] Slootweg reported equal prevalence in both the sexes. [5] The distribution is equal between maxilla and mandible, with molar-ramus area being the most common site. [5],[6] Almost all cases are associated with an impacted tooth. This case showed mandibular molar-ramus involvement with impaction of 48.

Swelling and failure of tooth eruption are the two most common presenting complaints. This case showed the above features associated with pain, lymphadenopathy, and trismus, which may be due to secondary infection.

The radiographic features of AFO include various amounts of radiopaque material of irregular size and form in a well-defined radiolucent area. The lesion may resemble an odontoma when the mineralized element in the tumor predominates. [7] The sizes of the lesions vary with some of them being exceedingly large, involving a considerable portion of the body of the mandible or maxilla. [8] This case showed a presentation similar to an odontoma, appearing primarily as a radiopaque lesion and involving a large portion of the mandible extending into the ramus.

In 2010, Tolentino et al. reported a similar case of AFO in the left mandibular molar-ramus area in a 11-year-old girl. In contrast to our case, there was no sign of pain or swelling due to the lesion. Radiographically, it appeared to be in intimate contact with the inferior alveolar nerve; contrary to our case, the inferior alveolar nerve was not seen radiographically at the site of the lesion even on the CBCT scan. Interestingly, similar to our case, even Tolentino et al. had presumably diagnosed it as a complex odontoma. [9] In 2011, Schussel et al. reported a similar lesion in the maxilla in a 3-year-old child, but the lesion was ill defined on radiography, contrary to our case in which the lesion was well defined. [10] In 2006, Yan-ping et al. reported an AFO of the maxilla which was a soft tissue mass with irregular areas of dense calcifications and causing the destruction of the maxillary ridge and sinus. Unlike our case, the lesion reported by Yan-ping et al. was entirely radiolucent. [11]

Histopathologically, the lesion shows narrow cords or strands or islands of odontogenic epithelium embedded in a myxoid cell-rich loose and primitive connective tissue stroma resembling the dental papilla. The soft tissue component of AFO is microscopically similar to the ameloblastic fibroma. [12] This case had been diagnosed with the same features histologically. The calcifying elements consist of foci of enamel and dentin matrix formation in close relation to the epithelial structures. According to Chen et al., irregular dentin and enamel formation due to the disorganized odontogenic epithelium in AFO makes it more unlikely that structures similar to teeth will be formed. [3] But in this case, the formation of denticles was clearly seen on the radiographs.

Most cases of AFO being hamartomatous are treated successfully by conservative enucleation with curettage, and as the lesion is well circumscribed and not invading the surrounding structures, recurrence is highly unusual. However, in 1999, Furst et al., reported recurrence of AFO in a 9-year-old boy. [13] The unerupted tooth should be removed along with the mass. [14] Though malignant transformation is very rare, Howell et al. reported two cases of AFO showing malignant transformation into ameloblastic fibrosarcoma. [15]

   Conclusion Top

A unique case of AFO is reported showing differentiation into complex and compound odontoma. Odontomas can be easily diagnosed radiographically and with the use of CBCT. They are less-aggressive, benign tumors, seldom recur after removal, and must be treated conservatively.

   References Top

1.Barnes L, Eveson JW, Reichart P, Sidransky D, editors. World Health Organization Classification of tumours. Vol 9. Pathology and genetics of head and neck tumours. Lyon, France: IARC Press; 2005.  Back to cited text no. 1
2.Buchner A, Merrell PW, Carpenter WM. Relative frequency of central odontogenic tumors: A study of 1,088 cases from Northern California and comparison to studies from other parts of the world. J Oral Maxillofac Surg 2006;64:1343-52.  Back to cited text no. 2
3.Chen Y, Li TJ, Gao Y, Yu SF. Ameloblastic fibroma and related lesions: A clinicopathologic study with reference to their nature and interrelationship. J Oral Pathol Med 2005;34:588-95.  Back to cited text no. 3
4.Cahn LR, Blum T. Ameloblastic odontoma, case report critically analysed. J Oral Surg 1952;10:169-70.  Back to cited text no. 4
5.Slootweg PJ. An analysis of the interrelationship of mixed odontogenic tumors - Ameloblastic fibroma, ameloblastic fibro-odontoma, and the odontomas. Oral Surg Oral Med Oral Pathol 1981;51:266-76.  Back to cited text no. 5
6.Hooker SP. Ameloblastoma Odontoma - An analysis of twenty six cases. Oral Surg 1967;24:375-6.  Back to cited text no. 6
7.Guerrisi M, Piloni MJ, Keszler A. Odontogenic tumors in children and adolescents. A 15-year retrospective study in Argentina. Med Oral Patol Oral Cir Bucal 2007;12:E180-5.  Back to cited text no. 7
8.Piette EM, Tideman H, Wu PC. Massive maxillary ameloblastic fibro-odontoma: Case report with surgical management. J Oral Maxillofac Surg 1990;48:526-30.  Back to cited text no. 8
9.de Souza Tolentino E, Centurion BS, Lima MC, Freitas-Faria P, Consolaro A, Sant'ana E. Ameloblastic fibro-Odontoma: A diagnostic challenge. Int J Dent 2010;2010. pii:104630.  Back to cited text no. 9
10.Sassi LM, Stramandinoli RT, Dissenha JL, Zanferrari FL, Schussel JL. Large ameloblastic fibro-odontoma in a 3 year-old child: Case report. Revista Sul-Brasileira de Odontologia 2011;8:114-6.  Back to cited text no. 10
11.Yan-Ping H, Bing L, Tong S, Wen-Feng Z, Yi-Fang Z. A huge ameloblastic fibro-odontoma of the maxilla. Oral Oncol EXTRA 2006;42:160-2.  Back to cited text no. 11
12.Neville B, Damm D, Allen C, Bouquot J. Oral and maxillofacial pathology. 3 rd ed. Philadelphia, PA: Saunders; 2011. p. 722.  Back to cited text no. 12
13.Furst I, Pharoah M, Phillips J. Recurrence of an ameloblastic fibro-odontoma in a 9-year-old boy. J Oral Maxillofac Surg 1999;57:620-3.  Back to cited text no. 13
14.Kumar PP, Sridhar BS, Vinod T. Ameloblastic fibro-odontoma in a 5-year-old girl- A case report. Journal of Indian Academy of Dental Specialists 2011;2:57-9.  Back to cited text no. 14
15.Howell RM, Burkes EJ Jr. Malignant transformation of ameloblastic fibro-odontoma to ameloblastic fibrosarcoma. Oral Surg Oral Med Oral Pathol 1977;43:391-401.  Back to cited text no. 15


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]


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