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 Table of Contents  
CASE REPORT
Year : 2019  |  Volume : 10  |  Issue : 1  |  Page : 147-153  

Hybrid ameloblastoma of anterior maxilla: A rare and puzzling pathologic entity – Case report with systematic review


Department of Oral Medicine and Radiology, Institute of Dental Studies and Technologies, Modinagar, Uttar Pradesh, India

Date of Web Publication17-Dec-2019

Correspondence Address:
Dr. Shalu Rai
Department of Oral Medicine and Radiology, Institute of Dental Studies and Technologies, Modinagar, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ccd.ccd_341_18

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   Abstract 

Hybrid ameloblastoma has a variable clinical, radiological, and histopathological presentation. They contain two or more different histologic types and their biologic comportment is still arguable. We herein present a case of a hybrid variant of desmoplastic ameloblastoma which is the first of its kind to have ever been reported due to its unusual location in the maxillary anterior region, along with systematic review of clinicopathologic features of reported cases immunohistochemical markers may act as an adjunct in the accurate diagnosis of these lesions.

Keywords: Desmoplastic ameloblastoma, hybrid ameloblastoma, immunohistochemistry, odontogenic tumor, systematic review


How to cite this article:
Rai S, Misra D, Prabhat M, Jain A, Jain P. Hybrid ameloblastoma of anterior maxilla: A rare and puzzling pathologic entity – Case report with systematic review. Contemp Clin Dent 2019;10:147-53

How to cite this URL:
Rai S, Misra D, Prabhat M, Jain A, Jain P. Hybrid ameloblastoma of anterior maxilla: A rare and puzzling pathologic entity – Case report with systematic review. Contemp Clin Dent [serial online] 2019 [cited 2020 Jan 18];10:147-53. Available from: http://www.contempclindent.org/text.asp?2019/10/1/147/273151


   Introduction Top


Ameloblastomas are the odontogenic tumors generally present in the jaw bones. They begin as a painless swelling of the jaws and gradually cause facial deformity, mobility, displacement, and root resorption of the involved teeth.[1] Most of the lesions occur in mandible ascending ramus and cause grotesque deformities. Radiologically, it appears as a mixed radiopaque-radiolucent lesion with well- or ill-defined margins having unilocular or multilocular appearance.[2]

The most common types of ameloblastomas are the follicular and plexiform types also called the “classic/conventional types,” followed by acanthomatous and granular cell types. In 1987, Waldron and El-Mofty presented a distinctive variant of ameloblastoma, which was called hybrid ameloblastoma displaying capricious combination of the histological features of desmoplastic ameloblastoma along with conventional ameloblastoma.[3] Being a rare entity, only a few cases of hybrid ameloblastomas have been reported globally, accounting for about 1.1%–4.3% of ameloblastomas. The literature also reports clinically and histologically different benign and locally invasive malignant lesions with some similar radiological features, thereby mimicking each other.[4],[5],[6] This diagnostic dilemma can be simplified by detailed three-dimensional imaging modalities such as cone-beam computed tomography (CBCT). Our case of hybrid ameloblastoma is by far the first of its kind owing to its inimitable combination of follicular, plexiform, and desmoplastic variants and involvement of anterior maxilla which is a very unusual site for ameloblastoma of any kind. The objective of this paper is to report histologically established hybrid ameloblastoma with areas of misdiagnosed as periapical cyst. It further reviews the clinicoradiological features and immunohistochemical markers of hybrid ameloblastoma and presents a systematic review of clinicopathologic features of hybrid ameloblastoma.


   Methodology Top


The present systematic review was conducted according to the guidelines provided by the PRISMA statement. A bibliographic search was performed in the main databases: PUBMED (www.pubmed.gov); ScIELO (www.scielo.org), Google Scholar (www. scholar.google.com.br), BVS (http://bvsalud.org/) e LILACS (http://lilacs.bvsalud.org), which we collected papers along with cross-references that were published from 1984 to 2018. It included laboratory studies, case reports, and systematic reviews as well as literature that were developed in the human species. Articles with cases of peripheral, malignant, metastatic, and recurrent ameloblastoma were excluded from the study. Through the bibliographic research, 85 articles were selected, all of which were extracted from: PUBMED (www.pubmed.gov); ScIELO (www.scielo.org), Google Scholar (www.scholar.google.com.br), BVS (http://bvsalud.org/) e LILACS (http://lilacs.bvsalud.org), previously reported. Keywords included a combination of “hybrid ameloblastoma” and/or “hybrid odontogenic tumours” ([MeSH Terms]).


   Results Top


The paper reviews a total of 49 cases. Clinical, radiological, and histopathological characteristics of each reported case have been identified and analyzed from papers published in the English Medical literature. These clinicoradiological and histopathological features are described in [Table 1] and [Table 2].
Table 1: Clinicoradiological and pathological features of hybrid ameloblastoma

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Table 2: Summary of data on 36 compiled cases of hybrid ameloblastoma

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   Case Report Top


A 35-year-old female patient reported to our department of Oral Medicine and Radiology complaining of pain in the upper front tooth region for the past six months. Patient revealed a past history of trauma in the same region 10 years back. Her previous medical and familial history was noncontributory. Extraorally, no swelling, no facial deformity, or expansion of cortical bone was observed. Cervical lymph nodes were not palpable. Intraoral hard tissue examination revealed intact maxillary anterior teeth. Soft-tissue examination revealed vestibular obliteration and tenderness present in relation to left maxillary anterior teeth; however, overlying mucosa was intact with no signs of infection and sinus tract formation [Figure 1]. Based on history and clinical features a provisional diagnosis of radicular cyst was given and the patient was subjected for chairside investigations such as tooth vitality and fine-needle aspiration cytology (FNAC). Pulp vitality tests were performed for 21, 22, and 23 and the teeth did not respond to electric and thermal stimuli and were found to be nonvital. FNAC was nonproductive. Hematological findings were within normal limits.
Figure 1: Clinical preoperative picture showing vestibular obliteration in the left maxillary anterior region

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Patient was advised for panoramic radiograph to visualize the extent of the lesion before surgical management could be planned. The panoramic radiograph revealed well-defined radiolucency extending from mesial to 21 involving 22 up to distal of 23. The border of the radiolucency was not corticated and internal structure revealed unclear radiolucency. There was no resorption of involved teeth with the radiolucency and no involvement of maxillary sinus on the left side [Figure 2]. A nonproductive FNAC, unclear superioinferior margins of the lesion and unclear internal structure of the lesion, raised doubts overdiagnosis of lesion, and patient was subjected for CBCT to uncover these doubts.
Figure 2: Panoramic radiograph with well-defined radiolucency extending from 21, 22, and 23

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CBCT multiplanar and axial sections [Figure 3], with three-dimensional reconstructed image [Figure 4], revealed solitary, oval, ill-defined, unilocular, complete radiolucency, with nonsclerotic border, surrounding the apical aspect of root of 21, 22, 23 causing complete destruction of labial plate at coronal aspect extending toward alveolar crest in 21, 22 region and superiorly leading to destruction of nasal floor, medially up to nasal septum, and distally till the distal aspect of root of 23. The lesion is measuring about 19.8 mm mesiodistally, 13.6 mm superioinferiorly and 15 mm buccolingually. Blunting or root of 21 and 22 was noted. Thinning of mesial aspect of the nasopalatine canal was also noted. The radiographic diagnosis of infected radicular cyst of 21 and 22 was given. Surgical enucleation of the lesion was performed and the surgical specimen was sent to histopathological examination.
Figure 3: Multiplanar view illustration in sagittal, coronal, and axial sections from cone-beam computed tomography

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Figure 4: Three dimensional illustration of pathology present from different views in different aspects

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Microscopic examination of the hematoxylin and eosin-stained slides reveal mature densely collagenized connective tissue stroma showing odontogenic epithelial cells forming a network of interconnecting strands [Figure 5]. These strands are bounded by a layer of columnar cells resembling ameloblast-like cells in the periphery with nuclei arranged away from the basal region of the cell showing reverse nuclear polarity. Between these layers, stellate reticulum-like cells are present. Fibrous stoma along with blood vessels is enclosed between the network of odontogenic cells and appears to be compressing or squeezing the odontogenic cell network [Figure 6] and [Figure 7]. In another section, small-to-medium-sized discrete compressed follicles of tumor cells with few areas of cystic degeneration can also be seen. The compressed follicles are surrounded by hyalinized stroma in various areas [Figure 8] and [Figure 9]. Myxomatous degeneration is also appreciable in certain areas. These findings were consistent with desmoplastic-plexiform-follicular (hybrid) ameloblastoma.
Figure 5: Interlacing strands of odontogenic epithelium in the connective tissue stroma showing plexiform pattern (H and E, ×4)

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Figure 6: Connective tissue stroma undergoing desmoplastic changes (H and E, ×10)

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Figure 7: Desmoplastic changes at higher magnification (H and E, ×40)

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Figure 8: Desmoplastic stroma compressing the epithelial islands (H and E, ×10)

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Figure 9: Epithelial island showing desmoplasia (H and E, ×10)

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   Discussion Top


Clinical and histopathological features of hybrid ameloblastoma

According to Waldron and El-Mofty, hybrid ameloblastoma is a rare variant of ameloblastoma which shows a unique combination of the histological features of desmoplastic ameloblastoma along with conventional ameloblastoma.[7]

As per the reported cases, the mandible is the most common site for involvement of hybrid ameloblastomas as compared to the maxilla.[8],[9],[10] Moreover, if the tumor occurs in the maxilla, then the posterior region is the most affected.[11],[12] Whereas in the present case, the maxillary anterior region was found to be involved making it a highly unique entity.

Philipsen et al. proposed that the hybrid variant was a transitional form of the desmoplastic type, comprising the microscopic features of both desmoplastic and classic follicular or plexiform variants which is in accordance to the histological features present in this case.

Radiographically, it mimics fibro-osseous diseases and odontogenic cysts and tumors with mixed radiolucent-radiopaque internal structure such as ossifying fibromas, fibrous dysplasia, osteoblastomas, osteosarcomas, calcifying epithelial odontogenic tumors, and calcifying odontogenic cysts.[8],[9],[10]

The hybrid variant appears such as mixed radiolucent and radiopaque lesions with irregular borders similar to common radiological pattern observed in the desmoplastic variant or fibro-osseous lesions or malignant tumors owing to high infiltrative nature.[11],[12] While few cases of hybrid ameloblastomas exhibit a multilocular radiolucent pattern, which is similar to that of conventional ameloblastomas, as was seen in our patient.

The incidence of desmoplastic variant ranges from 4% to 13% making it an extremely rare entity.[13],[14] The intriguing relationship of the desmoplastic variant with the conventional variants is the center of interest of many researchers worldwide. The simultaneous occurrence of desmoplastic variant with an additional variant in the hybrid lesion is enigmatic.[15],[16] It is still unclear whether the already existing desmoplastic variant transforms into the conventional variant or vice versa. Few researchers even consider it to be a collision tumor.[17],[18]

However, the histopathological features shown in our case are in agreement with Waldron and El-Mofty's diagnostic criteria because it showed the synchronized occurrence of desmoplastic variant along with other variants such as follicular and plexiform.[19],[20]

Immunohistochemistry of hybrid ameloblastoma

As a result of tumoral modulation in hybrid lesions immunohistochemically, expressions of extracellular matrix proteins, tenascin, fibronectin, and type I collagen, in a hybrid ameloblastoma lesion, have been reported.[21]

Treatment

With limited understanding of its behavior and prognosis, the proper treatment strategies for hybrid ameloblastoma are not entirely defined so far. Based on the present knowledge, the WHO recommends to apply the same treatment modality as for solid ameloblastoma which includes complete resection as enucleation or curettage might result in its recurrence, however, small lesions can easily be enucleated in toto.[22],[23],[24]


   Conclusion Top


Hybrid ameloblastoma has a variable clinical, radiological, and histopathological presentation. The biologic comportment of the lesion is still arguable. Immunohistochemical markers may act as an adjunct in the accurate diagnosis of this lesion. Thus, many more clinical, radiological, and histopathological data are required to clearly demonstrate this pathologic entity.

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.
Eversole LR, Leider AS, Hansen LS. Ameloblastomas with pronounced desmoplasia. J Oral Maxillofac Surg 1984;42:735-40.  Back to cited text no. 1
    
2.
Waldron CA, el-Mofty SK. A histopathologic study of 116 ameloblastomas with special reference to the desmoplastic variant. Oral Surg Oral Med Oral Pathol 1987;63:441-51.  Back to cited text no. 2
    
3.
Higuchi Y, Nakamura N, Ohishi M, Tashiro H. Unusual ameloblastoma with extensive stromal desmoplasia. J Craniomaxillofac Surg 1991;19:323-7.  Back to cited text no. 3
    
4.
Philipsen HP, Ormiston IW, Reichart PA. The desmo- and osteoplastic ameloblastoma. Histologic variant or clinicopathologic entity? Case reports. Int J Oral Maxillofac Surg 1992;21:352-7.  Back to cited text no. 4
    
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Louis PJ, Fugler RC, August M. Mixed radiolucent/radiopaque lesion of the maxilla. J Oral Maxillofac Surg 2000;58:86-90.  Back to cited text no. 5
    
6.
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. 6
    
7.
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. 7
    
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Madiyal A, Babu GS, Ajila V, Madi M, Castelino R, Rao K. Desmoplastic ameloblastoma masquerading as a fibro-osseous lesion. Cukurova Med J 2017;42:575-8.  Back to cited text no. 8
    
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Takata T, Miyauchi M, Ogawa I, Zhao M, Kudo Y, Sato S, et al. So-called 'hybrid' lesion of desmoplastic and conventional ameloblastoma: Report of a case and review of the literature. Pathol Int 1999;49:1014-8.  Back to cited text no. 9
    
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Angadi PV, Kale A, Hallikerimath S. “Hybrid” desmoplastic ameloblastoma: An unusual case report with immunohistochemical investigation for TGF-β and review of literature. East J Med 2011;16:9-17.  Back to cited text no. 10
    
11.
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. 11
    
12.
Yamazaki M, Maruyama S, Abé T, Babkair H, Fujita H, Takagi R, et al. Hybrid ameloblastoma and adenomatoid odontogenic tumor: Report of a case and review of hybrid variations in the literature. Oral Surg Oral Med Oral Pathol Oral Radiol 2014;118:e12-8.  Back to cited text no. 12
    
13.
Rai R, Reddy SP, Shaik JA. Hybrid lesion of ameloblastoma: A perplexing pathological entity. J Oral Health Dent Manage 2014;13:998-1002.  Back to cited text no. 13
    
14.
Chaitanya B, Chhaparwal Y, Pai KM, Kudva A, Cariappa KM, Acharya S, et al. Hybrid ameloblastoma: An amalgam of rare and conventional ameloblastoma. Contemp Clin Dent 2016;7:90-4.  Back to cited text no. 14
[PUBMED]  [Full text]  
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Rastogi R, Jain H, Mohan C, Rastogi V, Rastogi K. Hybrid ameloblastoma – An unusual combination of desmoplastic and conventional ameloblastoma. J Int Med Sci Acad 2010;23:237-8.  Back to cited text no. 15
    
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Brooks JK, Al-Mubarak H, Ribera MJ, Cohen PD, Ross DS, Scheper MA, et al. Diminutive, interradicular “hybrid” desmoplastic/acanthomatous ameloblastoma. Quintessence Int 2010;41:209-12.  Back to cited text no. 16
    
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Joshi P, Golgire S, Majati S. Hybrid desmoplastic ameloblastoma: A case report of rare entity and review of literature. J Dent Alli Sci 2014;3:47-51.  Back to cited text no. 17
    
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Mukhopadhyay S, Thomas CT, Bali K, Koshy S, Gaikwad P. Hybrid variant of desmoplastic ameloblastoma, a rare histomorphological entity – A case report and review of literature. J Oral Maxillofac Surg Med Pathol 2016;28:182-4.  Back to cited text no. 18
    
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Mahadesh J, Rayapati DK, Maligi PM, Ramachandra P. Unicystic ameloblastoma with diverse mural proliferation – A hybrid lesion. Imaging Sci Dent 2011;41:29-33.  Back to cited text no. 19
    
20.
Bavle RM, Thambiah LJ, Paremala K, Sudhakara M, Srinath N. Desmoplasia and osteoplasia in a hybrid ameloblastoma: A case report. Int J Oral Maxillofac Pathol 2013;4:42-5.  Back to cited text no. 20
    
21.
Gupta A, Jindal C. Hybrid ameloblastoma: Report of a rare case and review of literature. Int J Oral Maxillofac Pathol 2011;2:68-72.  Back to cited text no. 21
    
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Hirota M, Aoki S, Kawabe R, Fujita K. Desmoplastic ameloblastoma featuring basal cell ameloblastoma: A case report. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;99:160-4.  Back to cited text no. 22
    
23.
Feinberg SE, Steinberg B. Surgical management of ameloblastoma. Current status of the literature. Oral Surg Oral Med Oral Pathol 1996;81:383-8.  Back to cited text no. 23
    
24.
Sampson DE, Pogrel MA. Management of mandibular ameloblastoma: The clinical basis for a treatment algorithm. J Oral Maxillofac Surg 1999;57:1074-7.  Back to cited text no. 24
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9]
 
 
    Tables

  [Table 1], [Table 2]



 

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