|Year : 2014 | Volume
| Issue : 2 | Page : 93-96
Adenomatoid odontogenic tumor arising from dentigerous cyst: Report of a rare case
NT Geetha, Amarnath P Upasi, Kirthikumar Rai
Department of Oral and Maxillofacial Surgery, Bapuji Dental College and Hospital, Davangere, Karnataka, India
|Date of Web Publication||11-Sep-2015|
N T Geetha
Department of Oral, Maxillofacial and Reconstructive Surgery, Bapuji Dental College and Hospital, Davangere, Karnataka
Source of Support: None, Conflict of Interest: None
Adenomatoid odontogenic tumor (AOT) was described as a distinct odontogenic tumor by Stafne in 1948. It is the fourth most common odontogenic tumor which is benign, slowly growing and has three variants, follicular, extrafollicular, and peripheral. A follicular variety of AOT will be associated with an impacted tooth and most commonly gets confused with the dentigerous cyst. It is known fact that odontogenic cysts can be associated with odontogenic tumors. There are very few case reports of AOT arising within the dentigerous cyst. It's difficult to assess the behavior or treatment modifications for such type of lesions as the reported cases are less. They are treated conservatively by curettage and enucleation as both are benign in nature. Here, we report a case of AOT arising from the dentigerous cyst with an impacted canine in the anterior maxilla in a 14-year-old boy with emphasis placed on clinical, radiographic, and histological features in addition to its surgical management.
Keywords: Adenomatoid odontogenic tumor, dentigerous cyst, impacted canine
|How to cite this article:|
Geetha N T, Upasi AP, Rai K. Adenomatoid odontogenic tumor arising from dentigerous cyst: Report of a rare case. Int J Oral Health Sci 2014;4:93-6
|How to cite this URL:|
Geetha N T, Upasi AP, Rai K. Adenomatoid odontogenic tumor arising from dentigerous cyst: Report of a rare case. Int J Oral Health Sci [serial online] 2014 [cited 2019 Jul 21];4:93-6. Available from: http://www.ijohsjournal.org/text.asp?2014/4/2/93/165114
| Introduction|| |
The Adenomatoid odontogenic tumor (AOT) which was described initially as an adamantinoma in 1934, got the recognition as a distinct odontogenic tumor by Stafne in 1948. It is a benign, noninvasive lesion with a slow but progressive growth.  Until 1969, the tumor, which was called by many terms got its own identity and named as AOT thereafter. The credit goes to Philipsen and Birn who proposed that it is clearly distinguishable from ameloblastoma. AOT is the fourth most common odontogenic tumor. AOT can be divided into two variants, central (intraosseous) and peripheral (extraosseous). The central variant has follicular and extrafollicular subtypes. The follicular type will be associated with an impacted tooth and is the one which commonly gets confused with the dentigerous cyst. , There are reports of odontogenic cysts associated with odontogenic tumors. Combined features of odontogenic tumors with epithelial and mesenchymal components may arise within the odontogenic cysts because neoplastic and hamartomatous aberrations can occur at any stage of odontogenesis. 
| Case Report|| |
A 14-year-old boy reported to our unit with a complaint of a swelling on the left middle third of the face and also an intraoral swelling in the left maxillary vestibular region since 1-month. History of trauma was ruled out. Extraorally there was the obliteration of nasolabial fold and there was no bulging in the lateral wall of the nose. On intraoral examination, a firm, well-defined swelling extending from the left maxillary lateral incisor to first premolar was present. The permanent canine was missing and retained deciduous canine was evident. Mucosa over the swelling was erythematous. Swelling was non-tender. There was no history of oro antral or oronasal communication
Orthopantomogram revealed a well circumscribed, inverted pear shaped radiolucent lesion with a distinct radiopaque margin extending from the distal aspect of the root of lateral incisor to the mesial aspect of second premolar root associated with an impacted canine. Displacement of the roots of adjacent teeth and the lining of the maxillary sinus was evident [Figure 1]. Clinical diagnosis of a dentigerous cyst associated with an impacted canine was made.
Three milliliter of straw colored fluid was aspirated from the lesion and protein content was estimated to be 8.2 g/dl. Routine blood investigations were carried out. Surgery was planned in two stages. First stage: Marsupialization of the cystic lesion under general anesthesia (GA) was carried out. The prepared acrylic stent was placed in the created opening in the vestibule. Excised specimen's microscopy revealed cystic epithelium supported by a connective tissue wall. Epithelium was 2-3 layer in thickness resembled reduced enamel epithelium. Supporting connective tissue wall comprised of bundles of collagen fibers arranged parallel to the cystic epithelium. In some places, epithelial cells formed the rosette-like structures about a central space containing eosinophilic material. Few tubular or duct-like structures consisting of central space surrounded by a layer of cuboidal, columnar cells, nuclei of which are polarized away from the central space. Duplication of basal lamina can be appreciated in one field. Small foci of calcifications can be seen scattered at places. These were suggestive of AOT within the dentigerous cyst.
Regression of the lesion was observed after 2 months of stage one procedure in the radiograph, but the canine was not showing any evidence of eruption [Figure 2].
|Figure 2: Orthopantomogram after 2 months of stage one surgery showing regression of the lesion|
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The second stage was planned after 2 months, where enucleation of the cyst along with the removal of impacted permanent canine and over retained deciduous canine were carried out under GA. The postoperative course was uneventful, and patient is on regular follow-up [Figure 3].
Specimen was sent for histopathologic examination. Macroscopy showed a cystic structure surrounding the crown of the tooth measuring 2 cm × 1.5 cm × 1.2 cm [Figure 4]. The cyst wall is thickened and shows gray brown granular material attached to the inner surface. Microscopy revealed a fibrous wall lined partly at few places by flattened stratified epithelium and at few places by cords of small cells with eosinophilic hyaline material and calcified areas. The lumen of focal areas are composed of a solid nodule of cuboidal epithelial cells, duct-like structure lined by a row of columnar cells and occasional convoluted structures of tall columnar cells. Calcified areas and several dilated vascular channels. These were suggestive of AOT arising from the dentigerous cyst [Figure 5].
|Figure 4: Enucleated specimen showing dentigerous adenomatoid odontogenic tumor attached to the cementoenamel junction of canine|
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|Figure 5: H and E stained section showing Dentigerous cyst lining and the typical appearance of AOT with tubules, spindle cells and plexiform cords|
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| Discussion|| |
It has been estimated that the AOT accounts for 2.2-7.1% of all odontogenic tumors. The age range varies between 3 and 82 years. 68.6% occur in the second decade with more than half of the cases seen in teens. This age distribution with a very tall peak in the second decade makes it unique among odontogenic tumors. AOT is a slowly growing odontogenic tumor with a predilection for anterior maxilla of young females. The central variant of AOT accounts for approximately 96% of all AOTs of which 71% are of the follicular type. The central variant is more commonly found in the maxilla than in the mandible. The follicular type shows a well-defined, unilocular radiolucency associated with the crown and often part of the root of an unerupted tooth, thus mimicking a dentigerous or follicular cyst. In fact, 77% of follicular AOT are initially diagnosed as dentigerous cysts.  The clinical findings of our case were matching with the clinical findings of the other published literature.
Very few cases of AOT associated with dentigerous cysts are reported in the literature [Table 1]. , This tumor in association with the dentigerous cyst is reported to occur in the anterior as well as the posterior maxilla and even in the angle of the mandible. , In our case, it was in the anterior maxilla. The origin of AOT is controversial. As the tumor can arise anywhere in the jaw, the dental lamina complex is reported to play a major role in its origin. Philipsen et al. have strongly argued in favor of the concept of AOT being derived from the complex system of dental laminae or its remnants embedded in the gubernacular dentis. Gubernacular dentis consists of a fibrous band called gubernacular cord within the gubernacular bony canal, which connects the pericoronal tissue of the developing permanent tooth with the overlying gingiva. It guides the course of an erupting permanent tooth. The proliferation of epithelial remnants within the canal stimulated by still unknown mechanism results in the formation of the tumor. When the proliferation takes place close to the dental sac the initial tooth eruption may lead to the fusion between the tumor and the reduced enamel epithelium of the erupting tooth, resulting in embracement of tooth by the tumor. This explains the "envelopmental theory," which is responsible for the development of a pericoronal variant of AOTs. 96% of AOTs arise from this mechanism. , In case of an AOT arising within the cyst, we can think that the dentigerous cyst would develop initially from the unerupted tooth and then from unknown stimulation the epithelial rests in the cyst lining might give rise to AOT.  As the number of reported cases of AOT arising from the dentigerous cyst are very less, the stimulus responsible for the development of AOT from dentigerous cyst needs further research.
|Table 1: Data on reported cases of adenomatoid odontogenic tumor arising from a dentigerous cyst till now in the literature |
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As per the surgical management of these lesions is concerned, both these lesions have very less recurrent rates, so are treated conservatively. However, there are some reports of aggressive behavior of AOT where there has been an intracranial extension from the maxilla and also report of a case that had recurred after almost 7 years. ,, So in such cases treatment also needs to be aggressive, and we feel regular follow-up is mandatory. In some cases after surgical exposure, the impacted tooth associated with AOT begins to erupt spontaneously, and tumor tissue tends to regress. Even the impacted tooth can be moved orthodontically into its position. , Tooth associated with these lesions can be salvaged by the orthodontic movement itself, if the position and supporting structures favor it. Hence, we feel that regular follow-up is required in these cases to study their behavioral pattern.
We would like to thank Dr. Chatura KR, Professor, Department of Pathology, J. J. M. Medical College, Davangere, Karnataka for histopathological guidance.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]