|Year : 2015 | Volume
| Issue : 2 | Page : 50-54
An aggressive presentation of adenomatoid odontogenic tumor associated with calcifying epithelial odontogenic tumor: A hybrid variant
Shubhangi Mhaske1, Swapnil Moghe2, Monal Yuwanati1, Nikita Bhatnagar1, Mudita Rawal3
1 Department of Oral Pathology and Microbiology, Peoples Dental Academy, Bhopal, Madhya Pradesh, India
2 Department of Oral and Maxillofacial Surgery, Peoples Dental Academy, Bhopal, Madhya Pradesh, India
3 Department of Oral Medicine and Radiology, Peoples Dental Academy, Bhopal, Madhya Pradesh, India
|Date of Web Publication||22-Dec-2015|
Department of Oral Pathology and Microbiology, Peoples Dental Academy, Peoples Campus, Bhanpur, Bhopal - 462 037, Madhya Pradesh
Source of Support: None, Conflict of Interest: None
The adenomatoid odontogenic tumor (AOT) was formerly considered to be a variant of the ameloblastoma and was designated as adenoameloblastoma. It represents 3-7% of all odontogenic tumor and over 750 cases have been reported in the literature. Though this lesion shows pathognomic histological features, few overlapping patterns of the odontogenic tumors may be seen. AOT may infrequently show additional areas resembling to calcifying epithelial odontogenic tumor. Long-term follow-up research is need of the hour for such hybrid histological combination effect on the locally aggressive nature of the lesion. We present a case of a follicular variant of AOT in a 22 years male presenting with swelling on anterior maxilla associated with impacted canine.
Keywords: Adenomatoid odontogenic tumor, amyloid-like, calcification, calcifying epithelial odontogenic tumor, hybrid odontogenic tumor
|How to cite this article:|
Mhaske S, Moghe S, Yuwanati M, Bhatnagar N, Rawal M. An aggressive presentation of adenomatoid odontogenic tumor associated with calcifying epithelial odontogenic tumor: A hybrid variant. J Oral Res Rev 2015;7:50-4
|How to cite this URL:|
Mhaske S, Moghe S, Yuwanati M, Bhatnagar N, Rawal M. An aggressive presentation of adenomatoid odontogenic tumor associated with calcifying epithelial odontogenic tumor: A hybrid variant. J Oral Res Rev [serial online] 2015 [cited 2019 Jul 22];7:50-4. Available from: http://www.jorr.org/text.asp?2015/7/2/50/172494
| Introduction|| |
Adenomatoid odontogenic tumor (AOT) is an uncommon pathology of odontogenic origin. It was first described by Steensland and reported by Harbitz as a cystic adamantinoma.  Philpsen and Birn proposed the term "AOT" which is currently in use, adenomatoid odontogenic tumor. It is also considered as a hamartoma because of its limited size, minimal growth potential, and lack of recurrence. , It has a greater tendency to occur in anterior maxilla involving an unerupted permanent tooth, usually lateral incisor and canine and has a young female predilection.  AOT usually appears as a well-defined radiolucent area, sometimes with a variable amount of radio-opacity of mineralization indicative of calcified areas within tumor tissue.  The incidence of combined AOT with calcifying epithelial odontogenic tumor (CEOT) is uncommonly seen as documented in literature [Table 1]. AOT and CEOT are clearly defined entities as different lesions in the category of odontogenic epithelial tumors. 
|Table 1: Adenomatoid odontogenic tumor cases showing calcifying epithelial odontogenic tumor-like areas reported in literature|
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| Case Report|| |
A 22-year-old male patient presented with a bony expansile swelling in right maxilla [Figure 1]. The swelling had gradually increased in size (5 cm × 4 cm × 4 cm approximately) in the period of 3-4 months. The swelling was extended superioinferiorly from right infraorbital rim to level of angle of mouth and mediolateraly from right zygomatic buttress to ala of nose causing obliteration of nasolabial fold. Intraorally, obvious labial and palatal cortical plate expansion were noted adjacent to right first premolar (#14) and first molar (#16). The vestibular obliteration was seen though the overlying mucosa was normal [Figure 2]. Right, maxillary lateral incisor (#12) was grade II mobile. The lesion was asymptomatic. The orthopantograph and intraoral periapical X-rays were taken. Radiographs showed a large, ill-defined radiolucent area extending from permanent lateral incisor to mesial aspects of a maxillary second molar. The impacted canine was seen within the radiolucent area in close approximation to the floor of the orbit. Central incisor (#11), premolars (#14, #15) and first molar (#16) tooth root resorption [Figure 3]. Contrast computed tomography scan showed an expansile lytic lesion, with intact cortex seen in right side mandible body, just reaching midline, and lesion shows internal mildly inhomogeneously enhancing soft tissue [Figure 4]. With a provisional diagnosis of a cystic lesion, aspiration was done which yielded aspiration of 4.3 ml clear straw colored fluid. The biochemical investigation revealed the presence of 4.9 g protein/100 ml.
|Figure 2: Intramurally missing #13 and over-retained #57, 14 palatally angulated|
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|Figure 3: Orthopantomogram showing cystic radiolucency with impacted canine associated with #11, impacted #13 can be seen lying close to the floor of orbit (black arrow)|
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|Figure 4: Computed tomography scan showing heterogeneous soft tissue density with right buccal and palatal bony expansion|
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Clinical and radiographic findings indicated dentigerous cyst associated with an impacted permanent maxillary right canine. Complete surgical excision was carried out with the extraction of permanent right maxillary lateral incisor (due to poor prognosis) and the involved impacted permanent maxillary right canine. Rest of all the teeth was conserved with apical seal and apisectomy. The excised specimen was solid compressible soft tissue, spherical in shape, and brownish in color. It measured approximately about 5 cm × 4 cm × 3.5 cm in size. The canine was enclosed within the ovoid mass. The cut surface revealed soft tissue attached to cervical part of canine and a large cystic cavity with the thick wall was enclosing the crown of the tooth. Irregular nodular thickenings from the wall of lesional tissue were protruding within the cystic lumen.
Histopathology revealed a cystic cavity with a thick collagenous cystic wall [Figure 5]. The cyst was lined by a variable thickness of the lining of dentigerous cyst in few areas. The lining showed luminal multinodular tumor proliferations composed of spindle cells, columnar and cuboidal preameloblast such as cells in the form of tubular, duct-like, and "rosette" patterns. The duct-like areas were showing eosinophilic lamellar material adjacent to the preameloblast like cells lining the lumen (Hyaline-ring) [Figure 6].
|Figure 5: Lesional tissue showing cellular multinodular odontogenic epithelial proliferation with peripheral fi brous capsule|
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|Figure 6: Luminal multinodular proliferations shows spindle-shaped cells in tubular and duct-like structures|
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Areas of polygonal shaped odontogenic cells were seen in sheets and islands with prominent intercellular bridges. Calcification in droplet form and in the form of Liesegang ring were present [Figure 7]. These findings are indicative of the presence of combination AOT and CEOT like areas in the same lesion. The final diagnosis was given as AOT. There was no recurrence observed in the period of 1-year follow-up.
|Figure 7: Calcifying epithelial odontogenic tumor-like basophilic calcified areas with liesegang ring pattern seen in epithelial cells with dark staining nuclei and prominent intercellular junctions are noted within the lesional tissue|
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| Discussion|| |
There are clinic-pathological variants of AOT, namely a follicular-dentigerous type, extrafollicular type, peripheral or extraossesous type. , Histologically, all three types show almost similar features diagnostic for AOT. A follicular variant shows nodular tumor proliferation in the cystic lining toward the lumen. These mural nodules grow and multiply to form a neoplastic solid mass. This clinically represents a central lesion associated with an impacted tooth. An extrafollicular variant is not related to unerupted tooth and presents as a de novo entity adjacent to the roots of erupted teeth. The peripheral variant appears as gingival fibroma or epulis.  Pathogenesis relates to the theory of follicular origin same as of dentigerous cyst, ameloblastoma, and other epithelial odontogenic tumors.
Radiologically, the tumor presents as a unilocular or multilocular radiolucency. There is a common misdiagnosis of a dentigerous cyst when this lesion is viewed radiologically. Dentigerous cyst shows enclosing of the crown of the tooth whereas the AOT may enclose entire tooth.  Irregular tooth resorption is common findings displacement of teeth may be seen with obvious mobility. Minute calcific deposits may be noted in 58% of AOTs. 
Histologically, AOT characteristically presents with a glandular or ductal pattern of preameloblast like cells in a multinodular arrangement of the stroma. The presence of eosiophilic amyloid-like material is seen within the stroma. Few calcific droplets are seen. The present case also showed an interesting finding of CEOT like areas. Though this has been reported as a "Hybrid tumor;" nowadays it is being documented as usual findings. 
The common say is that predominant areas like AOT and the lesion behave more like AOT. However, we would like to put forth a hypothesis that the aggressive behavior of the follicular variant of AOT and CEOT characteristics. This lesion presented as an aggressive lesion with resorption, displacement and mobility of teeth.
These CEOT areas were more evident in the periphery of the lesion mounting to the expansile growth of the lesion. These were approximately 25-30% of the lesion. These findings were initially supported by Damm et al. and Takeda and Kudo et al. had supported the mixed tumor concept with immunohistochemistry of keratin (TK and KL-1 keratin), lectin binding (concanavalin A, peanut agglutinin, soybean agglutinin, wheat germ agglutinin) was determined to show the features common to the lesions. ,
Recent concepts do accept the facts that like areas exist. However, even with countable numbers of similar cases reported in literature, they do not give an actual behavioral pattern of lesions with combined features of AOT and CEOT and AOT showing AOT features alone. ,, There could be a possibility of development of CEOT in an AOT, which may later the lesion progression.
Though these so-called hybrid lesions do not appear in the standard WHO classification of odontogenic tumors, this category having mixed or hybrid pictures should be given valid significance.
According to few authors, the tumors presenting as CEOT and AOT combinations are not considered as true hybrids; rather they should be identified simply as anomalous histodifferentiation and/or morphodifferentiation process. 
According to Melrose, the designation hybrid tumor serves no real purpose. It is probably due to the expression of the histomorphodifferentiation potential of the epithelium and the mesenchyme and their complex inductive interaction, from which these lesions are derived.  We propose that reconsideration of the fact of combined histological features giving rise to such actual findings need to be discussed thoroughly based on histogenesis and should not be ignored as being misnomers. Such lesions should be included in standard WHO classifications with distinctive criteria of diagnosis.
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.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]