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 Table of Contents  
CASE REPORT
Year : 2018  |  Volume : 30  |  Issue : 1  |  Page : 78-81

Rare variant of ameloblastoma: A case report


Department of Oral Medicine and Radiology, Tamil Nadu Govt. Dental College, Affiliated to The Tamil Nadu Dr MGR Medical University, Chennai, Tamil Nadu, India

Date of Submission13-Oct-2017
Date of Acceptance03-Mar-2018
Date of Web Publication23-Apr-2018

Correspondence Address:
Dr. Bhaumik Joshi
Department of Oral Medicine and Radiology, Tamil Nadu Govt. Dental College, Affiliated to The Tamil Nadu Dr MGR Medical University, Chennai, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jiaomr.jiaomr_67_17

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   Abstract 


Ameloblastoma is second most common odontogenic tumor of jaws that presents with typical clinical, radiological, and histopathological appearances. Provisional diagnosis of this tumor is based on clinical and radiological features; however, final diagnosis is made by histopathological examination which classifies it in to various types, i.e. follicular, plexiform, acanthomatous, granular cell, desmoplastic, and basal cell type. Follicular and plexiform patterns are most common. Hybrid ameloblastoma (HA) is rare entity in which conventional types (follicular and plexiform) of ameloblastoma co-exist with desmoplastic ameloblastoma (DA). Its radiological appearance differs from conventional ameloblastomas and sometimes resembles fibro-osseous lesions (FOL). There are only 35 cases of HA reported in literature. We present a novel case of hybrid desmoplastic/follicular ameloblastoma of anterior mandible with emphasis on its radiologic features. Differential diagnosis of the lesion from conventional ameloblastomas and FOL are discussed.

Keywords: Ameloblastoma, cone-beam computed tomography, desmoplastic, differential diagnosis, fibro-osseous lesion, follicular, hybrid


How to cite this article:
Paramasivam R, Sadaksharam J, Joshi B. Rare variant of ameloblastoma: A case report. J Indian Acad Oral Med Radiol 2018;30:78-81

How to cite this URL:
Paramasivam R, Sadaksharam J, Joshi B. Rare variant of ameloblastoma: A case report. J Indian Acad Oral Med Radiol [serial online] 2018 [cited 2021 Dec 9];30:78-81. Available from: https://www.jiaomr.in/text.asp?2018/30/1/78/230897




   Introduction Top


Desmoplastic ameloblastoma (DA) accounts for only 4–13% amongst all types of ameloblastomas.[1] Co-existence of conventional (follicular or plexiform) pattern of ameloblastoma with DA is called hybrid ameloblastoma (HA). DA differs in radiological presentation from conventional ameloblastomas, and in some instances, it may give impression of fibro-osseous lesions (FOL). According to PubMed database, there are only 35 cases of HA reported till date.[2],[3] Here we have presented a novel case of HA with focus on its unique radiological presentation and differential diagnosis.


   Case Report Top


A 48-year-old male presented with a swelling over left anterior mandibular teeth region. Patient noticed the swelling 4 months back, that gradually increased to reach the present size. On clinical examination, the swelling was sessile, hard, and non-tender [Figure 1].
Figure 1: Intraoral picture of a swelling present in relation to left mandibular incisors and canine. Note obliteration of labial vestibule caused by swelling

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Mandibular occlusal radiograph revealed a lesion in relation to left incisors and canine with buccal cortical plate expansion and thinning. The lesion showed mixed radiolucent-radiopaque appearance with honey-comb trabecular pattern and totally radiolucent internal structures [Figure 2].
Figure 2: Mandibular occlusal radiograph shows buccal cortical plate expansion and thinning. Note internal structure showing honeycomb trabecular pattern laterally (arrow) and complete radiolucency medially (arrowhead)

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Orthopantomograph (OPG) revealed evidence of an ill-defined, mixed radiolucent-radiopaque lesion extending from mandibular left central incisor to mandibular canine. It showed distal and mesial tipping of mandibular left lateral incisor and left canine respectively [Figure 3].
Figure 3: Orthopantomograph showing of an ill-defined, mixed radiolucent-radiopaque lesion present in anterior mandible. Tipping of left mandibular lateral incisor and canine is evident

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In contrast to OPG [Figure 3], the panoramic reconstruction done in cone-beam computed tomography (CBCT) revealed a well-defined lesion with evidence of internal structure showing multilocular - honeycomb pattern [Figure 4].
Figure 4: Panoramic reconstruction in cone-beam computed tomography showing well-defined lesion with honeycomb pattern internal structure

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Axial, coronal, and sagittal multiplanar reconstruction of CBCT revealed buccal cortical plate expansion with thinning and perforation [Figure 5]a. Thinning and perforation of lingual cortical plate without expansion also was noted [Figure 5]c. The internal structure of the lesion showed mixture of two patterns – a multilocular honeycomb pattern and completely hypodense interior [Figure 5]b and [Figure 5]c. Lesion had well-defined peripheral margins.
Figure 5: Cone-beam computed tomography (CBCT) axial, coronal, and sagittal sections showing (a) Buccal cortical plate expansion, thinning, and perforation. (b) Hybrid internal structure having a multilocular pattern and a completely hypodense cystic pattern. (c) Buccal cortical plate expansion, thinning, and perforation; and hybrid internal structure. Also note thinning and perforation of lingual plate

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Patient's serum calcium, phosphorous, and alkaline phosphatase levels were within normal limit. Based on these findings, diagnosis of DA of anterior mandible was made with differential diagnosis of FOL. The lesion was surgically resected. Microscopic sections showed compressed strands and cords of odontogenic epithelium in a densely hyalinized and hypocellular stroma along with presence of follicles of odontogenic epithelium with peripheral tall columnar ameloblast like cells with reversal of polarity and central stellate reticulum like cells suggestive of hybrid lesion of DA and follicular ameloblastoma [Figure 6].
Figure 6: A photomicrograph showing evidence of epithelial cell islands and cords in a densely hyalinized connective stroma (desmoplastic ameloblastoma) and follicles of odontogenic epithelium with peripheral tall columnar ameloblast like cells and central stellate reticulum like cells (follicular ameloblastoma)

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The patient is kept under regular follow-up and an 8-month follow-up has showed a satisfactory healing and bone formation in excised lesion site with no evidence of recurrence [Figure 7].
Figure 7: An 8-month postoperative radiograph showing healing of lesion site with filling of trabecular bone

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   Discussion Top


Ameloblastoma is second most common odontogenic tumor. In India it is reported to be the most common odontogenic tumor.[4] It has peak incidence in third to fourth decade of life with no gender predilection. It is most often found in the posterior body and angle of the mandible. Radiologically, ameloblastoma can have a multilocular or unilocular pattern. The multilocular pattern can have soap-bubble, spider-web, or honeycomb appearances. Periphery of the lesion can be smooth or scalloped. Usually bicortical expansion and thinning along with perforation in advanced stages is seen.[5],[6]

DA is the latest addition in WHO Classification of Ameloblastoma. It accounts for only 4–13% amongst all types of ameloblastomas. In contrast to conventional ameloblastomas, it is more common in female and has a predilection for the anterior and premolar regions of the maxilla and mandible.[1] Tumor growth factor beta (TGF-β) plays a part tumor modulation in DA, and not in conventional ameloblastomas.[7] DA has unique radiological features. On plain radiography it may present as mixed radiolucent/radiopaque lesion with ill-defined borders resembling FOL. However, three-dimensional (3D) examination shows the lesion to be having well-defined borders as 3D images can avoid the tissue superimposition to provide more accurate and clearer borders. This feature helps in differentiating this lesion from FOL. Characteristic CBCT feature of DA is the honeycomb-like appearance formed by coarse trabecular septa. Some lesions may have plenty of radiopaque flecks scattered around the radiolucent region or a “hybrid pattern” with a honeycomb-like area conjugated with a radiolucent cystic portion. The hybrid type may be concealed in OPG when the radiolucent cyst is located at the labial or lingual side of the lesion and completely overlaps with the honeycomb-like area. Another characteristic feature is the expansion of a lesion only on the labial side with partial cortical erosion as opposed to bicortical expansion caused by conventional ameloblastomas.[8] Our case presented with ill-defined borders on mandibular occlusal and OPG [Figure 2] and [Figure 3]; however, on CBCT images it had well-defined margins [Figure 5]b. CBCT images showed monocortical expansion with two distinct areas of the lesion comprising of: (1) honeycomb-like appearance formed by coarse trabecular septa present towards the lingual side of lesion and (2) a completely hypodense cystic appearance on labial side of the lesion, giving it a hybrid appearance [Figure 5]a and [Figure 5]c.

HA is characterized by areas of follicular or plexiform ameloblastoma coexisting with areas of DA.[2],[7] It remains unknown if in HA, DA develops from conventional ameloblastoma, vice versa or HA is a kind of collision tumor.[1] Immunohistochemistry suggests that tenascin and fibronectin may participate in tumoral modulation.[9] A review of literature done in 2017, based on database of PubMed, revealed only 35 cases of HA being reported in literature. HA appears to be more common females with majority of cases occurring in age group of 30–59 years. It is more common in mandible.[3]

DA exhibits more aggressive behaviour than other types of ameloblastoma and it is apparent from frequent histological detection of bone invasion. DA displays a significantly higher recurrence after enucleation than after resection and should be kept under observation.[10]


   Conclusion Top


DA has specific clinical and radiological features and should be included as differential diagnosis for any FOL or neoplastic growth of anterior maxilla or mandible. We have presented a unique case of HA with unique radiological features. Detailed 3D examination with CBCT helps in differentiating it from FOL. It has high recurrence rate and hence should be followed-up at regular intervals.

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.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Philipsen HP, Reichart PA, Takata T. Desmoplastic ameloblastoma (including “hybrid” lesion of ameloblastoma). Biological profile based on 100 cases from the literature and own files. Oral Oncol 2001;37:455-60.  Back to cited text no. 1
[PUBMED]    
2.
Waldron CA, el-Mofty SK. A histopathologic study of 116 amelobastomas with special reference to the desmoplastic variant. Oral Surg Oral Med Oral Pathol 1987;63:441-51.  Back to cited text no. 2
[PUBMED]    
3.
Iwase M, Fukuoka A, Tanaka Y, Saida N, Onaka E, Bando S, et al. Hybrid desmoplastic/follicular ameloblastoma of the mandible: A case report and review of the literature. Case Rep Pathol 2017;2017:7031414.  Back to cited text no. 3
[PUBMED]    
4.
Sriram G, Shetty RP. Odontogenic tumors: A study of 250 cases in an Indian teaching hospital. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;105:e14-21.  Back to cited text no. 4
    
5.
More C, Tailor M, Patel HJ, Asrani M, Thakkar K, Adalja C. Radiographic analysis of ameloblastoma: A retrospective study. Ind J Dent Res 2012;23:698.  Back to cited text no. 5
    
6.
Jayachandran S, Singh K. Imaging analysis of ameloblastoma of mandible – 5 cases. J Analytical Oncol 2012;1:164-8.  Back to cited text no. 6
    
7.
Angadi PV, Kale A, Hallikerimath S, Kotrashetti V, Mane D, Bhatt P, et al. 'Hybrid' desmoplastic ameloblastoma: An unusual case report with immunohistochemical investigation for TGF-β and review of literature. Eastern J Med 2011;16:9-17.  Back to cited text no. 7
    
8.
Luo J, You M, Zheng G, Xu L. Cone beam computed tomography signs of desmoplastic ameloblastoma: Review of 7 cases. Oral Surg Oral Med Oral Pathol Oral Radiol 2014;118:126-33.  Back to cited text no. 8
    
9.
dos Santos JN, De Souza VF, Azevêdo RA, Sarmento VA, Souza LB. “Hybrid” lesion of desmoplastic and conventional ameloblastoma: Immunohistochemical aspects. Braz J Otorhinolaryngol 2006;72:709-13.  Back to cited text no. 9
    
10.
Mintz S, Velez I. Desmoplastic variant of ameloblastoma: Report of two cases and review of the literature. J Am Dent Assoc 2002;133:1072-5.  Back to cited text no. 10
[PUBMED]    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]


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1 Clinico-Radiological assessment of Unicystic Ameloblastoma of mandible a case report
Sadakshram Jayachandran, A.V. Annapoorni
Clinical Dentistry. 2020;
[Pubmed] | [DOI]



 

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