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 Table of Contents  
CASE REPORT
Year : 2014  |  Volume : 4  |  Issue : 2  |  Page : 84-88

Extensive ameloblastic fibroma of the mandible: Report of a case with a special reference to its aspiration cytologic findings


1 Department of Oral Pathology and Microbiology, Subharti Dental College, Meerut, Uttar Pradesh, India
2 Department of Oral Medicine and Radiology, Subharti Dental College, Meerut, Uttar Pradesh, India

Date of Web Publication11-Sep-2015

Correspondence Address:
Suhasini Palakshappa Gotur
Department of Oral Pathology and Microbiology, Subharti Dental College, Meerut, Uttar Pradesh
India
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Source of Support: Nil., Conflict of Interest: There are no conflicts of interest.


DOI: 10.4103/2231-6027.165107

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  Abstract 

Ameloblastic fibroma (AF) is an extremely rare benign odontogenic tumor with a relative frequency between 1.5% and 4.5%, which usually occurs in the first two decades of life. AF is a true mixed tumor, in which the epithelial and the ectomesenchymal elements are neoplastic. There are two variants of AF: Neoplastic and hamartomatous. Although the histopathology of hamartomatous and neoplastic variants of AF are indistinguishable, clinical, and radiologic features can be of some help to distinguish between them. Asymptomatic small unilocular lesions with no or minimal bone expansion in young individuals are likely to be developing odontomas, and large, expansile lesions with extensive bone destruction are neoplasms. We herein describe a massive AF involving mandible in a 12-year-old female patient, suggestive of the neoplastic variant, with a special reference to its aspiration cytologic findings. Fine-needle aspiration cytologic smears showed two different types of cellular elements: A gland like epithelial component, arranged in well-outlined clusters of basaloid cells with palisading of the columnar cells at the borders of those clusters, and a mesenchymal component that consisted of loosely arranged fusiform cells. These cytologic features appear to be sufficiently characteristic to suggest a diagnosis of AF by fine-needle aspiration. However, the confirmatory diagnosis was made on the basis of histopathology, which proved it to be an AF.

Keywords: Ameloblastic fibroma, cytopathology, fine-needle aspiration, mandible


How to cite this article:
Gotur SP, Aggarwal P, Wadhwan V, Kamarthi N. Extensive ameloblastic fibroma of the mandible: Report of a case with a special reference to its aspiration cytologic findings. Int J Oral Health Sci 2014;4:84-8

How to cite this URL:
Gotur SP, Aggarwal P, Wadhwan V, Kamarthi N. Extensive ameloblastic fibroma of the mandible: Report of a case with a special reference to its aspiration cytologic findings. Int J Oral Health Sci [serial online] 2014 [cited 2019 Jul 21];4:84-8. Available from: http://www.ijohsjournal.org/text.asp?2014/4/2/84/165107


  Introduction Top


Ameloblastic fibroma (AF) is defined by WHO as "neoplasm composed of proliferating odontogenic epithelium embedded in cellular ectomesenchymal tissue, that resembles the dental papilla and epithelial strands and varying degrees of inductive changes and dental hard tissues formation." The nature of AF is controversial. The 1992 WHO classification does not include a definition of AF as an entity. AF is a relatively uncommon, slow-growing benign neoplasm of odontogenic origin, which is characterized by simultaneous proliferation of both epithelial and mesenchymal tissues without the formation of enamel or dentin.[1]


  Case Report Top


A 12-year-old female reported with a chief complaint of large swelling in her left lower third of the face of 3 months duration [Figure 1]a: Inset], swelling was hard in consistency with diffuse borders, nonfluctuant, non compressible, and nontender on palpation. Intraoral examination revealed swelling extending from 33 up to the anterior border of the ramus of the mandible, causing vestibular obliteration. On lingual aspect, swelling was mildly perceptible. The overlying mucosa was intact and normal in color and consistency. All the teeth present were vital with grade I mobility with respect to 36 and grade III mobility with respect to 75.
Figure 1: ( a) (inset) Clinical picture of patient showing swelling in left lower third of the face. (b) Panoramic radiograph showing an extensive multilocular radiolucent lesion extending from 33 tooth bud, up to coronoid and condylar process, with involvement of entire ramus of the left mandible, missing 35 tooth bud, displacement of the 37, and pathological fracture on posterior aspect of mandibular ramus (arrow)

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A panoramic radiograph [Figure 1]b revealed multilocular radiolucent lesion with sclerotic borders, extending from 33 tooth bud up to coronoid and condylar process, with the involvement of entire ramus. The lesion had caused root resorption of 36 and displacement of 37 to inferior border of the mandible. It also revealed missing 35 tooth bud and pathological fracture on the posterior aspect of the mandibular ramus (arrow). Straight and curved course septae were arranged tangentially giving a tennis racket appearance, suggestive of the odontogenic tumor.

Mandibular occlusal view [Figure 2]a showed multilocular radiolucent lesion. Intraoral periapical radiograph showed mesial root resorption of 36 [Figure 2]b.
Figure 2: (a) Mandibular occlusal view showing multilocular radiolucent lesion. (b) Intraoral periapical radiograph showing mesial root resorption of 36

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On fine-needle aspiration, a gelatinous material was retrieved. Smears obtained by aspiration from the lesion, stained with hematoxylin and eosin (H and E), and showed two different types of cellular elements: A gland like epithelial component and a mesenchymal component. The epithelial component showed well-outlined cohesive clusters of monomorphic cells with peripheral palisading by columnar cells, resembling the basaloid or ameloblast-like cells and central polygonal cells. At the edges of these clusters, the cells showed nuclear palisading. The palisading cells had eosinophilic cytoplasm with poorly defined cytoplasmic outlines. The nuclei were round to oval and possessed finely dispersed chromatin and indistinct nucleoli. The stromal fragments within the aspirate were composed of streaming spindle cells of relatively uniform appearance possessing indistinct cellular borders and hypochromatic spindle to ovoid nuclei. No cytologic atypia, necrosis, or mitotic activity was seen. Few desquamated squamous cells were also seen. These features were suggestive of a benign odontogenic tumor, most likely an AF [Figure 3]a and [Figure 3]b.
Figure 3: (a) Photomicrograph of the smear prepared with the aspirate showing clusters of basaloid cells in mesenchymal component consisting of loosely arranged fusiform cells (H and E, ×10). (b) Peripheral palisading by ameloblast-like tall columnar cells, showing nuclear hyperchromasia (H and E, ×40). (c) Cords and islands of odontogenic epithelium in a primitive connective tissue background resembling a dental papilla (H and E, ×10). (d) The peripheral cells resembling ameloblasts with central stellate reticulum like cells (H and E, ×40)

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An incisional biopsy was performed and sent for histopathological examination. Microscopically, H and E sections showed loose ectomesenchymal stroma, showing numerous fusiform cells in delicate collagenous matrix resembling dental papilla. Within the stroma, numerous sharply defined odontogenic islands were seen which were in the form of follicles and cords. These islands showed peripherally arranged tall columnar ameloblast-like cells showing hyperchromatism and reverse polarity, and the central cells were loosely arranged resembling stellate reticulum. Despite high cellularity, dysplastic features were not found [Figure 3]c and [Figure 3]d. The overall features confirmed the diagnosis of AF.

The tumor was resected under general anesthesia and was sent for histopathological examination, which once again confirmed the diagnosis of AF.


  Discussion Top


Ameloblastic fibroma was first described by Krause in 1891. AF is reported to occur at an age ranging 1-month – 57 years,[2] especially during the first two decades of life, with a slight male predilection. Mandible is the predominant site of occurrence, and the posterior mandible is affected more often than the maxilla by a factor of 3:1. Impacted, unerupted teeth are associated with AF in three-quarter of the cases. AF may develop in areas of congenitally missing teeth also. Radiographically, the tumor is characterized as a well-defined unilocular or multilocular radiolucency often with a sclerotic border.[3]

There are two variants of AF: Neoplastic and hamartomatous (the early state of a developing odontoma). Since the histopathology of these two variants is indistinguishable, only clinical and radiologic features can be of potential help to distinguish between them.[2] Cahn and Blum proposed the continuum concept based on the assumption that an AF will mature overtime and finally result in the formation of odontoma. Some points contradicting this theory were raised:[3]





  • Recurrent cases of AF have never shown further steps of differentiation into the dental hard tissue forming odontogenic tumor of more advanced histodifferentiation
  • Ameloblastic fibromas are known to occur at ages beyond completion of odontogenesis, that is, after the age of 20 years. Hence, it was proposed that AFs occurring after the age of 20 years are a true benign neoplasm. All cases of AF developing during the entire period of odontogenesis, however, may represent nonneoplastic hamartomatous lesion.[3]


Rapid extensive growth within 3 months, radiographically missing 35, displacement of the crown of 37 to the inferior border of the mandible, root resorption of 36, and pathological fracture on posterior aspect of mandibular ramus, suggest the present case to be of neoplastic subtype.

Granular cell AF and peripheral AF are the rare variants of AF.[4] Histologically, it is necessary to distinguish AF from ameloblastoma and ameloblastic fibrosarcoma since these two tumors can be locally invasive and have greater potential for recurrence than AF. Clinically, AF occurs at a younger age than ameloblastoma. Radiographic examination, however, does not contribute to the differential diagnosis because all these tumors may appear as unilocular or multilocular or circumscribed lesions.[5] In the present case, the aspiration cytology gave a definitive diagnostic hint, which was later confirmed by histopathology. Fine-needle aspiration cytologic smears from the present case showed two different types of cellular elements: A gland like epithelial component, arranged in well-outlined clusters of basaloid cells with palisading of the columnar cells at the borders of those clusters, and a mesenchymal component that consisted of loosely arranged fusiform cells. These cytologic features appear to be sufficiently characteristic to suggest a diagnosis of AF by fine-needle aspiration, which were consistent with previous case reports.[6],[7]

There have been limited cases reported on the cytologic findings of histologically verified AF. The cases, the age of occurrence, and cytopathological findings, together with the current case are summarized in [Table 1].[6],[7],[8],[9]
Table 1: Reported cases of ameloblastic fibromas with aspiration cytologic findings

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On occasions, aspiration cytologic findings of AF can raise differential diagnostic problems with ameloblastoma (another odontogenic tumor with radiological features on occasions similar to those of AF) and with tumors of the salivary gland,[10] that are rare.

Aspirates from AFs closely resemble those of ameloblastoma. The presence of ragged-edged aggregates of hypercellular stroma distinguishes the two lesions.[11] In the present case also, the cytosmear showed a mixture of complex branching epithelial structures as well as irregularly edged aggregates of the hypercellular stroma, which were in favor of AF than the ameloblastoma. These findings, in conjunction with the clinical and radiological information, were sufficient for a correct cytologic diagnosis of AF.

Some authors suggested the use of proliferating indices such as AgNOR, proliferating cell nuclear antigen, and Ki-67 for the evaluation of cellular proliferative activity and could be of help in understanding tumor aggressiveness and in selecting appropriate surgical procedure and possibly, to suggest the malignant development.[12]

AF is treated by enucleation and curettage of the surrounding bone and removal of the affected teeth. Some authors advocate a more aggressive therapy, that is, modified block resection of the mandible with the placement of an immediate autologous bone graft for an extensive tumor and/or multiple recurrences. Recurrence commonly results from incomplete removal of the tumor. Because of its high recurrent rate and a possibility of malignant transformation, the term "benign tumor" in case of AF should not falsely impart a simultaneous designation of "nonaggressive." Complete excision with close follow-up is highly recommended.[12] Considering the extensiveness of the lesion and the presence of a pathological fracture, resection was done in the present case.

Malignant transformation of AF was found to be associated with oncogenic aberrations in tumor-related genes. Mesenchymal proliferation within the tumor resulting in a loss of an epithelial component is a usual presentation of sarcomatous changes of AF. Hence, the histological distinction between ameloblastic fibrosarcoma arising from preexisting AF and conventional (true) ameloblastic fibrosarcoma seems to be difficult. Reviewing the previous histopathological slides when the tumor recurs is beneficial. If malignant changes occur in both epithelial and stromal components, the tumor is dubbed "ameloblastic carcinosarcoma."[12]


  Conclusion Top


Fine-needle aspiration is not usually the first diagnostic method in odontogenic tumors, probably due to the fact that an incisional biopsy is easily and rapidly carried out. Nevertheless, the cytological study can be very useful in cases of metastatic disease or in the follow-up of possible recurrences. However, it should always be supplemented with the histopathological diagnosis. Fine-needle aspiration apart from being fairly accurate, safe, and minimally invasive, has also added the benefit of the lack of need for anesthesia except in selected cases. The cytologic features in the present case appeared to be sufficiently characteristic to suggest a diagnosis of AF by fine-needle aspiration, confirmed by histopathological examination.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Chen Y, Wang JM, Li TJ. Ameloblastic fibroma: A review of published studies with special reference to its nature and biological behavior. Oral Oncol 2007;43:960-9.  Back to cited text no. 1
    
2.
Buchner A, Vered M. Ameloblastic fibroma: A stage in the development of a hamartomatous odontoma or a true neoplasm? Critical analysis of 162 previously reported cases plus 10 new cases. Oral Surg Oral Med Oral Pathol Oral Radiol 2013;116:598-606.  Back to cited text no. 2
    
3.
Jindal C, Bhola RS. Ameloblastic fibroma in six-year-old male: Hamartoma or a true neoplasm. J Oral Maxillofac Pathol 2011;15:303-5.  Back to cited text no. 3
[PUBMED]  Medknow Journal  
4.
Takeda Y. Ameloblastic fibroma and related lesions: Current pathologic concept. Oral Oncol 1999;35:535-40.  Back to cited text no. 4
    
5.
Munde AD, Karle RR, Kale UB. Ameloblastic fibroma in one-year-old girl. J Oral Maxillofac Pathol 2013;17:149.  Back to cited text no. 5
[PUBMED]  Medknow Journal  
6.
Carrillo R, Cuesta C, Rodríguez-Peralto JL, Marín J. Ameloblastic fibroma. Report of a case with fine needle aspiration cytologic findings. Acta Cytol 1992;36:537-40.  Back to cited text no. 6
    
7.
Bocklage TJ, Ardeman T, Schaffner D. Ameloblastic fibroma: A fine-needle aspiration case report. Diagn Cytopathol 1997;17:280-6.  Back to cited text no. 7
    
8.
Kumar N, Jain S. Aspiration cytology of ameloblastic fibroma: A diagnostic challenge. Diagn Cytopathol 2003;29:101-4.  Back to cited text no. 8
    
9.
Alam K, Khan R, Jain A, Maheshwari V, Agrawal S, Chana RS, et al. The value of fine-needle aspiration cytology in the evaluation of pediatric head and neck tumors. Int J Pediatr Otorhinolaryngol 2009;73:923-7.  Back to cited text no. 9
    
10.
Artes-Martínez MJ, Prieto-Rodríguez M, Navarro-Hervás M, Peñas-Pardo L, Camañas-Sanz A, Vaquero de la Hermosa MC, et al. Ameloblastoma. Diagnosis by means of FNAB. Report of two cases. Med Oral Patol Oral Cir Bucal 2005;10:205-9.  Back to cited text no. 10
    
11.
Gnepp DR. Fine needle aspiration biopsy. Diagnostic Surgical Pathology of the Head and Neck. 2nd ed., Ch. 15. Philadelphia: Elsevier Inc.; 2009. p. 1106-7.  Back to cited text no. 11
    
12.
Pitak-Arnnop P, Chaine A, Dhanuthai K, Bertrand JC, 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. 12
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
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