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An Official Publication of the Indian Association of Oral and Maxillofacial Pathologists

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Year : 2023  |  Volume : 27  |  Issue : 5  |  Page : 60-63

Ameloblastic fibroma: A case report

1 Department of Oral and Maxillofacial Pathology and Oral Microbiology, Career Post Graduate Institute of Dental Sciences and Hospital, Ghaila, Lucknow, Uttar Pradesh, India
2 Department of Oral and Maxillofacial Surgery, Career Post Graduate Institute of Dental Sciences and Hospital, Ghaila, Lucknow, Uttar Pradesh, India

Date of Submission08-Aug-2022
Date of Decision14-Sep-2022
Date of Acceptance15-Sep-2022
Date of Web Publication04-Feb-2023

Correspondence Address:
Abdullah Nasir
504/59 Tagore Marg, Daliganj, Lucknow - 226 020, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jomfp.jomfp_337_22

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Ameloblastic fibroma is a rare mixed odontogenic benign tumor that can occur in either mandible or maxilla but mostly it is found in posterior region of mandible. It can present either peripherally or centrally with a majority of the cases predominantly occurring in first two decades of life and mostly affects male patients. It is characterized by epithelial islands and cords submerged in ectomesenchyme that bear resemblance to the dental papilla and enamel organ but without actual hard tissue formation. Ameloblastic fibroma is a rare odontogenic tumor consisting of neoplastic epithelial and mesenchymal tissues. Recent reports have suggested that this lesion has the potential for high recurrence (18%) and greater chances of recurrent Ameloblastic fibroma transforming into Ameloblastic fibrosarcoma (45%). A 34-year-old male patient presented with pain and swelling in right mandibular posterior region. Intraorally expansion of buccal cortical plate with tenderness over swelling was present. Extraoral examination revealed facial asymmetry on right side. In view of imaging and clinical findings, provisional diagnosis of Odontogenic Keratocyst or Recurrent Ameloblastoma was considered. After obtaining informed consent and general systemic evaluation, the lesion was enucleated under general anesthesia and biopsied which confirmed the diagnosis of Ameloblastic fibroma. Ameloblastic fibroma is a mixed odontogenic tumor composed of odontogenic ectomesenchyme resembling dental papilla with epithelial strands and nests similar to the dental lamina and enamel organ, but with no dental hard tissue formation. Odontogenic tumors, Ameloblasts, Ameloblastoma, Jaw neoplasm.

Keywords: Ameloblastic fibroma, ameloblastic fibrosarcoma, enucleation, odontogenic tumors

How to cite this article:
Nasir A, Khare A, Ali I, Khan MI. Ameloblastic fibroma: A case report. J Oral Maxillofac Pathol 2023;27, Suppl S1:60-3

How to cite this URL:
Nasir A, Khare A, Ali I, Khan MI. Ameloblastic fibroma: A case report. J Oral Maxillofac Pathol [serial online] 2023 [cited 2023 Mar 27];27, Suppl S1:60-3. Available from: https://www.jomfp.in/text.asp?2023/27/5/60/369177

   Introduction Top

Ameloblastic fibromas are one of the rare varieties of benign odontogenic tumors structured with proliferating odontogenic epithelium planted in a cellular ectomesenchymal tissue bearing resemblance to dental papilla.[1]

They are frequently found in the posterior region of mandible with 80% cases in the second deciduous molar or first permanent molar region[2] and 75% associated with an impacted tooth.[3] These tumors are frequently discovered between the 1st and 2nd decades of life with 75% of cases being diagnosed before the age of 20 and essentially considered a tumor of childhood and adolescence. Males are affected more than females in the ratio of 1.4:1.[4]

Radiographically, ameloblastic fibromas are seen as well-defined unilocular or multilocular radiolucencies with sclerotic radiopaque borders.[5] Unilocular lesions present as asymptomatic cases, while the multilocular cases are often presented as swelling of jaw.[6] most of the cases of ameloblastic fibromas are found incidentally upon routine examination.[7] Ameloblastic fibromas needs to be demarcated from ameloblastoma, dentigerous cyst, odontogenic keratocyst, central giant cell granuloma, and histiocytosis.[8] If any mitotic cells are present or atypical mitotis is seen malignant odontogenic tumor such as Ameloblastic fibrosarcomas should be considered in differential diagnosis.[9]

Histopathologically, ameloblastic fibromas are made up of both the epithelial and connective tissue components; the connective tissue component resembles dental papilla containing spindled and angular cells with delicate collagen, giving a myxomatous appearance. The epithelial derivative is arranged in thin branching cords or small nests with little cytoplasm and basophilic nuclei, while stellate reticulum like cells is mostly seen in larger nests.[10]

Ameloblastic fibromas, in general, is treated with traditional approach such as enucleation with curettage of the adjacent bone along with the extraction of the affected tooth.[11] Long-term follow-up is done to check for any recurrence.[9]

This report describes a case of Ameloblastic fibroma in a 34-year-old male patient who came to Department of Oral and Maxillofacial Surgery of our college with chief complain of pain and swelling in right lower back region of jaw since one month.

   Case Report Top

In October 2021, a 34-year-old male patient reported to Department of Oral and Maxillofacial Surgery with pain and swelling in right lower back region of jaw. Patient had identified swelling 1 month back. His dental history was of ameloblastoma which was operated upon 10 years back in the same region.

On intraoral examination, obliteration of the right lower buccal vestibule was seen due to the expansion of buccal cortical plate. The mucosa over the swelling was same as surrounding mucosa. The swelling measured approximately 3 × 4 cm extending anteroposteriorly from mandibular second premolar to retromolar area on right side. On palpation the swelling was bony hard in consistency and mild tenderness over the swelling was seen.

Extra oral examination revealed facial asymmetry with extraoral swelling on the right side of face. On palpation the swelling was tender with hard consistency and was fixed to the deeper tissues. There was no involvement of the lymph nodes.

Orthopantomograph revealed well defined multilocular radiolucency with sclerotic borders extending from mandibular right first molar to second molar. The patient gave history of Ameloblastoma in the same region which had been operated upon 10 years back.

In view of the imaging and clinical findings, the presumptive diagnostic hypothesis of recurrent Ameloblastoma or OKC was potentially considered. After obtaining prior consent, complementary examination of systemic conditions was done and in absence of any systemic conditions, the surgical procedure was done. The patient was given general anesthesia and the lesion was removed by enucleation and the tissue was sent to Department of Oral Pathology and Microbiology for histopathological diagnosis.

Macroscopically the tissue removed was brownish in color, soft in consistency measuring approx. (A) 2.5 cm × 1.8 cm × 1.5 cm (B) 1.5 cm × 1.1 cm × 1.0 cm

Microscopic examination revealed ameloblastic islands with keratinization, focal areas showing compressed epithelial strands and cords [Figure 1] and other areas showing epithelial islands lined by elongated ameloblast like cells. Few cells had clear cytoplasm resembling clear cells. Connective tissue stroma was moderately collagenous with few chronic inflammatory cell infiltrates chiefly composed of lymphocytes and plasma cells, few blood vessels lined by endothelial cells were also present [Figure 2]. In this sense, the characteristics investigated confirmed the diagnosis of ameloblastic fibroma.
Figure 1: Higher magnification reveals compressed strands of cuboidal to columnar odontogenic epithelium resembling ameloblasts with hyaline-like material surrounding the strands

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Figure 2: Moderately collagenous connective tissue stroma with few chronic inflammatory cells and few blood vessels lined by endothelial cells

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The case was continued and the control radiography 3 months after surgery revealed diffuse radiopacity in the operated area.

   Discussion Top

Ameloblastic fibroma was first described by Kruse in 1892, later on it was characterized as benign neoplasia by Thoma and Goldman in 1946, and in 1992 it was included in mixed neoplasms by the World Health Organization.[12]

Ameloblastic fibroma is a true mixed odontogenic tumor and comprise of both epithelial and mesenchymal constituents occurring mostly in young patients in first or second decades of life.[2],[13] The lesion is mostly seen in the posterior region of mandible.[3] Ameloblastic fibromas are more common in males than females.[4]

As epithelial and mesenchymal components are seen in ameloblastic fibromas, it is considered as true biphasic tumor. The epithelium and connective tissue epitomize the cap and the bell stages of odontogenesis. Frequency of occurrence of Ameloblastic Fibroma is between 1.5 and 4.5%. According to Reichart and Philipsen, male-to-female predilection was 1.4:1. The average age of occurrence is around 14 years with a wide range of 2 to 62 years. It is a slow developing tumor which is usually located in the mandibular posterior region and is mostly associated with an impacted tooth. In cases of tumor near the surface of bone, slight buccal and lingual cortical plate expansion may be seen.[11]

Ameloblastic fibromas are usually unilocular lesions radiographically, larger lesions may be multilocular, with smooth well-defined borders. Expansion of cortex may not be evident on radiographic film. They may be confused as dentigerous cyst as these lesions are usually associated with unerupted teeth.[9] Ameloblastoma, odontogenic myxoma, KCOT, central granular cell tumor, and histiocytoma are the differential diagnosis radiologically.[14]

The pathogenesis of ameloblastic fibromas is not clear exactly. The tall columnar ameloblast-like cells in the epithelial component are too primeval to influence the cells of the ectomesenchyme, and very less is known about their interactions. It is also not clear why induction of odontoblastic differentiation is lacking in Ameloblastic Fibroma.[15] Positive staining of odontogenic epithelium for cytokeratin is seen in Immunohistochemical analysis, tenascin for staining of mesenchymal tissue, vimentin for staining of basement membrane. These findings suggest that ameloblastic fibromas mostly develop at an early stage of odontogenesis.[11]

Histological variants of ameloblastic fibromas are granular cell Ameloblastic Fibroma, Papilliferous Ameloblastic Fibroma,[15] Ameloblastoma in association with Ameloblastic Fibroma, and Cystic Ameloblastic Fibroma. Granular cell variant has predominantly granular cell in ectomesenchyme, Papilliferous variant shows marked proliferation of epithelium with plexiform arrangement.[16] The shape and direction of enlargement of the epithelial follicle was found to be affected by the density of collagen fibers in Ameloblastic Fibroma. Enlargement of epithelial follicle is restricted in areas of dense collagen fibers leading to its growth in planes of less resistance.[11] In the current case, there was no hard tissue formation, thus eliminating ameloblastic fibro odontoma or fibrodentinoma. In our case atypical features and mitotic activity were also not observed.[18]

Microscopically, Ameloblastic Fibroma comprises strands and islands of odontogenic epithelium in a loose and primitive connective tissue stroma resembling dental papilla. Tiny islands resembling the follicular stage of the developing enamel organ may be observed.[11],[17],[19] Recurrent cases of Ameloblastic Fibroma show dentin formation with or without enamel structure and they may differentiate into odontomas.[11],[19] The presence of mitosis should suggest the differential diagnosis of malignant lesions like ameloblastic fibrosarcoma. In cases undergoing malignant transformation, there are unambiguous changes in the mesenchymal component and the odontogenic epithelium is completely disappeared.[11],[19]

MIB-1, a monoclonal antibody against proliferation associated nuclear antigen, in Ameloblastic Fibroma ranged from 2.9 to 7.5% and from 1.5 to 13.5% in the epithelial and mesenchymal components, respectively. These indices were higher in recurrent Ameloblastic Fibroma and Ameloblastic fibroma sarcoma.[20]

   Conclusion Top

Ameloblastic Fibroma is a benign odontogenic mixed tumor, with a very good prognosis. Treatment is usually conservative, enucleation and curettage of the surrounding tissue is done under local anesthesia. Recurrence of the lesion is common after excision, so long term follow up is necessary after the removal of the lesion.

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.

   References Top

Kramer RH, Pindborg JJ, Shear M. The WHO histological typing of odontogenic tumours. Cancer 1992;70:2988-94.  Back to cited text no. 1
Reichart PA, Philipsen HP. Ameloblastic fibroma. In Odontogenic Tumors and Allied Lesions. London, UK: Quintessence Publishing Co. Ltd.; 2004. p. 121.  Back to cited text no. 2
Takeda Y. Ameloblastic fibroma and related lesions: Current pathologic concept. Oral Oncology, 1999;35:535-40.  Back to cited text no. 3
Cohen DM, Bhattacharyya I. Ameloblastic fibroma, ameloblastic fibro-odontoma, and odontoma. Oral Maxillofac Surg Clin North Am 2004;16:375-84.  Back to cited text no. 4
Slootweg PJ. An analysis of the interrelationship of the mixed odontogenic tumors—amelobastic fibroma, ameloblastic fibroodontoma, and the odontomas. Oral Surg Oral Med Oral Pathol 1981;51:266-76.  Back to cited text no. 5
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. 6
Barnes L, Eveson JW, Reichart PA, Sidransky P. Pathology and Genetics of Tumours of the Head and Neck: World Health Organization Classification of Tumours: International Histological Classification of Tumors. 3rd ed. Lyon, France: IARC Press; 2005.  Back to cited text no. 7
Regezi JA, Sciubba JJ, Jordan RC. Oral Pathology Clinical Pathologic Correlations. Amsterdam, The Netherlands: Elsevier; 4th ed; 2003.  Back to cited text no. 8
Nelson BL, Folk GS. Ameloblastic fibroma. Head Neck Pathol 2009;3:51-3.  Back to cited text no. 9
Kobayashi K, Murakami R, Fujii T, and Hirano A. Malignant transformation of ameloblastic fibroma to ameloblastic fibrosarcoma: Case report and review of the literature. J Craniomaxillofac Surg 2005;33:352-355.  Back to cited text no. 10
Gupta S, Tandon A, Mehrotra D, and Gupta OP. Ameloblastic fibroma: Report of 3 cases and literature review. Int J Oral Maxillofac Pathol 2011;2:59-63.  Back to cited text no. 11
Sanadi A, Shah SJ, Golgire S, Shetti S. Highly proliferative ameloblastic fibroma: A rare entity. Contemp Clin Dent 2018;9:656-8.  Back to cited text no. 12
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Tuna EB, AK Gulsum, Genacy K. Ameloblastic fibroma: A case report with five years follow up. Acta Stomatol Croat 2008;4:185-91.  Back to cited text no. 14
Peter AR, Hans PP. Odontogenic Tumors and Allied Lesions. 1st ed. Hanover Park, Ill, USA: Quintessence Publishing; 2004.  Back to cited text no. 15
McGuinness NJ, Faughnan T, Bennani F, Connolly CE. Ameloblastic fibroma of the anterior maxilla presenting as a complication of tooth eruption: A case report. J Orthod 2001;28:115-8.  Back to cited text no. 16
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Pitak – Arnnop P, Chaine A, Dhanuthai K, Charles Bertrand J, Bertolus C. Extensive ameloblastic fibroma in an adolescent patient: A case report with a follow up of 4 years. Eur J Dent 2009;3:224-8.  Back to cited text no. 19
Sano K, Yoshida SI, Ninomiya H, Ikeda H, Ueno K, Sekine J, et al. Assessment of growth potential by MIB-1 immunohistochemistry in ameloblastic fibroma and related lesions of the jaws compared with ameloblastic fibrosarcoma. J Oral Pathol Med 1998;27:59-63.  Back to cited text no. 20


  [Figure 1], [Figure 2]


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