Adenomatoid Odontogenic Tumor Associated with an Impacted Maxillary Lateral Incisor: A Case Report with Five-Year Follow-Up

Adenomatoid odontogenic tumor (AOT), a benign (hamartomatous) lesion of odontogenic origin, is an uncommon tumor which affects mainly females in the second decade. This lesion is most commonly associated with an impacted maxillary canine. This paper reported a case of AOT, in a 16-year-old female, associated with an impacted maxillary left lateral incisor. The evolution of this tumor was followed over 36 months and 24 months after excision.


Introduction
Dreibaldt in 1907 was the rst to describe adenomatoid odontogenic tumor (AOT), which is an uncommon benign epithelial lesion of odontogenic origin known as a pseudoadenoameloblastoma [1]. e term "adenomatoid odontogenic tumor" proposed by Philipsen et al. [2] indicates that it was not a variant of ameloblastoma [2,3]. In the World Health Organization classi cation of odontogenic tumors established in 1971, AOT was mentioned [1,4] as a mixed odontogenic neoplasm, in other words, an epithelial tumor with an inductive e ect on the odontogenic mesenchyme [1,5].
It represents 3-7% of all odontogenic tumors, and over 750 examples have been reported in the literature. Some authorities feel that, given the slow growth and circumscription of the lesion, it is best classi ed as a hamartoma rather than a true neoplasm [3]. e adenomatoid odontogenic tumor is mostly limited to younger patients between 10 and 30 years [3,6,7], and two-thirds of all cases are diagnosed when the patient is 10-19 years old. is tumor is uncommon in a patient older than 30 years. It has a striking tendency to occur in the anterior portion of the jaws (95%) and is found twice as often in the maxilla (65%) than in the mandible. Females are a ected about twice as often as males [3,6,8].
Most AOTs are relatively small. ey seldom exceed 3.0 cm in greatest diameter, although a few large lesions have been described with a greater diameter of 7 cm [6]. Peripheral (extraosseous) forms of the tumor are also encountered but are rare [3,8,9].
AOT is frequently asymptomatic and is revealed during a routine radiographic examination or when radiographs are made to determine why a tooth has not erupted [3,10]. A delayed eruption of a permanent tooth or a swelling of the jaws may be the rst symptom [7]. Larger lesions cause a painless expansion of the bone [3,8].
ere are three variants of AOT. Follicular type (73%) has an intrabony lesion (central) associated mostly with an impacted tooth and is usually misdiagnosed as a dentigerous cyst or follicular cyst. Extrafollicular type (24%) has an intrabony lesion and no connection with the tooth. It is usually presented as a well-de ned unilocular radiolucent image above or superimposed on the roots of the erupted teeth and often resembling a residual globulomaxillary or lateral periodontal cyst. Peripheral type (3%) usually presents as a gingival swelling and often appears as small, sessile masses on the buccal maxillary gingiva. Clinically, these lesions cannot be di erentiated from the common gingival brous lesion [3,4].
In about 75% of cases, the tumor appears as a circumscribed, well-de ned unilocular radiolucency that involves the crown of an unerupted tooth, most often a canine which represents approximately 60% of cases. Permanent incisors, premolars, molars, and deciduous teeth are rarely involved [8,10]. is follicular type of AOT may be impossible to di erentiate radiographically from the more common dentigerous cyst. e radiolucency associated with the follicular type of AOT sometimes extends apically along the root past the cementoenamel junction. is feature may help to distinguish an AOT from a dentigerous cyst [3,9,10].
Microscopically, the tumor is composed of spindleshaped epithelial cells that form sheets, strands, or whorled masses of cells in a scant brous stroma. e epithelial cells may form rosette-like structures around a central space, which may be empty or contain a small amount of eosinophilic material. is material may stain for amyloid [3,10].
AOTs are benign and present a very low recurrence, making it unnecessary to carry out extensive and aggressive surgery [2,3]. e surgical management of this lesion would be enucleation along with the associated impacted tooth because of its capsule; it enucleates easily from the bone [3].  In this paper, a case of AOT in the anterior maxillary region associated with a permanent lateral incisor will be reported. e evolution of this tumor was followed for 36 months before enucleation and 24 months after.

Case Report
A 16-year-old female consulted with a chief complaint of an asymptomatic swelling mass persistent from approximately 12 months on the left maxillary anterior region which increased gradually and achieved the present size of 1.5 cm.
e history revealed an orthodontic treatment started in December 2011 with a treatment plan involving extraction of teeth #34, 44, 23, and 14. e extraction of the impacted left maxillary canine was recommended due to its buccal position and absence of the vestibular cortical bone as shown on a Cone Beam Computerized Tomography (CBCT) (Figure 1). A surgical exposition of the crown and bonding of a bracket on the maxillary left lateral incisor were also planned a coronoplasty of the rst premolar to a canine shape. A radiolucency cyst-like was noted on the lateral incisor ( Figure 1) and was diagnosed as a dentigerous cyst. e extraction of the tooth #23 was done in April 2012, with surgery to bond a bracket on tooth #22, but it failed due to lack of the localization and the consistency of the tissues around the impacted tooth.
Her medical observation was noncontributory.
On extraoral examination (Figure 2(a)), facial asymmetry was noted. A solitary well-de ned swelling on the left side of the face in the region of the nasal ala was palpable. e swelling was roughly oval, measuring approximately 2.5 cm in diameter, extending superoinferiorly from 0.5 cm above the ala of the nose to the midpart of the upper lip, mediolaterally from 0.5 cm lateral to the corner of the mouth to the nasolabial fold, causing mild asymmetry of the face. e skin over the swelling appeared normal. On palpation, the swelling was nontender, hard in consistency, and xed to the underlying bone.
Intraoral examination (Figure 2(b)) revealed a solitary smooth circumscribed swelling of 1.5 cm × 2 cm in size, with well-demarcated margins in the left maxillary region lling buccal vestibule. Anteroposteriorly, it extended from the mesial margin of the rst premolar up to the distal margin of the second premolar. e buccal cortex was expanded, and the surface of the swelling was smooth with a normal color of overlying mucosa. e consistency was bony hard and non uctuant. On palpation, mild tenderness was present at one point. e swelling was slow growing; it gradually increased in size and led to the dis gurement of the face.
Teeth examination revealed that teeth #22 and 23 are missing, and teeth #21 and 24 are positive at cold sensitivity test without mobility. e axial slides of CBCT ( Figure 3) showed a wellcircumscribed radiolucent lesion with well-de ned radiopaque border extending horizontally from maxillary midline to the distal margin of the second premolar and vertically from the nasal base to the midpart of the roots of teeth #21 and 24. It is associated with an impacted lateral incisor. is radiolucency covers all crowns, and it overlaps the root of tooth #22.
Di erential diagnosis of this image revealed a rst dentigerous cyst, an adenomatoid odontogenic tumor, and a calcifying odontogenic cyst.

Case Reports in Dentistry
An enucleation was done. e tumor was well encapsulated, and the lateral incisor was easily removed with the lesion (Figure 4). e histopathologic examination conrmed the diagnosis of a follicular AOT type.
Microscopically, the tumor is composed of spindleshaped epithelial cells that form sheets, strands, or whorled masses of cells in a scant brous stroma. e epithelial cells may form rosette-like structures around a central space, which may be empty or contain a small amount of eosinophilic material ( Figure 5). is material may stain for amyloid. e healing was controlled for three weeks ( Figure 6). e control orthopantomogram on the third month ( Figure 7) followed by other on six months later showed normal bone trabeculation at the lesion site without recurrence. An orthopantomogram and CBCT were realized two years after for control, and placing an implant at the level of tooth #22 showed a reduction in the bone width in this region with complete bone healing (Figure 8).
A well-demarcated radiolucent lesion associated with the crown of impacted teeth like in this case ruled out the apical cyst, calcifying odontogenic cyst, odontogenic keratocyst, and central giant cell granuloma [10,11,14]. An apical cyst is usually associated with an endodontic-treated or morti ed pulp tooth, but in this case, the teeth #21 and 24 were positive to cold sensitivity test. Calcifying odontogenic cyst, odontogenic keratocyst, and giant cell granuloma were ruled out because usually they are mostly not related to the crown of an impacted tooth, and they are mostly multilocular.
Dentigerous cyst, unicystic ameloblastoma, ameloblastoma, and ameloblastic broma are most frequent in the posterior region of the mandible and are associated in most cases with the third molar. However, adenomatoid odontogenic tumor occurs mostly in the anterior maxillary region and is associated in 60% of cases with a canine [3,10,14,15].
A possible di erential diagnosis for the lesion described in this case report is a dentigerous cyst and an adenomatoid odontogenic tumor.
Adenomatoid odontogenic tumor (AOT) is an odontogenic epithelial tumor [5,14,15] that is more commonly found in young female patients between 10 and 19 years of age. e maxilla is more commonly a ected than the mandible. e size of the lesion ranges from 2 to 7 cm with a slow growing pattern which results in a painless expansion of the jaws. e canine is the most commonly impacted tooth [6,10,16]. In this case, a 16-year-old female presented with a well-demarcated radiolucent lesion of 2.5 cm diameter in the anterior maxillary region associated with an impacted permanent lateral incisor. e tumor was slowly growing within sixteen months; it lled the canine socket after extraction and expanded buccally to ll the buccal fold.
Mostly, AOTs are the central follicular type and appear as well-demarcated radiolucent lesions. AOT usually surrounds an unerupted tooth, and it looks as a corticated radiolucency with small radiopacities, but there are cases where the lesion has no radiopaque component, and in such cases, a dentigerous cyst is the preferred di erential diagnosis. However, an AOT often appears to envelop the crown as well, where we divided the specimen to show the relation of the lesion to the tooth, unlike the dentigerous cyst which does not surround the roots [1,3,14,16]. In this case, the lesion surrounded the entire crown and overlapped the root of the lateral incisor. Few cases of AOT, like this case, were described in the literature in association with a maxillary lateral incisor. e histological typing of the WHO de ned the AOT "like a tumor of odontogenic epithelium with duct-like structures and with varying degrees of inductive change in the connective tissue. e tumor is well encapsulated and shows an identical benign behavior" [1,9,16]. e treatment of choice was a surgical management of this tumor. It should be enucleated along with the associated impacted tooth and simple curettage [2,6]. Conservative treatment is adequate because the tumor is not locally invasive, is well encapsulated, and can be easily separated from the bone. e surgical specimen may be solid or cystic. e recurrence rate is as low as 0.2%. However, in exceptional cases of large tumors or risk of bone fracture, partial resection, in a block of the mandible or maxilla, has been indicated. Also, the use of lyophilized bone and guided tissue regeneration are recommended in extended osseous cavities. e prognosis is excellent in the majority of the cases [2,3,10]. In this case, as described, enucleation was done with the impacted lateral incisor, which was removed with the lesion. e tumor is well encapsulated and covered the entire crown and overlapped the root of the lateral incisor. Follow-up 12-24 months after surgery was performed, and no recurrence was noted.

Conclusion
AOTs are usually asymptomatic lesions that sometimes may cause cortical expansion and displacement of the adjacent teeth; the slow growing nature of the lesion may cause the patient to tolerate the swelling for years until it produces an obvious facial deformity. Early diagnosis of this by the dental surgeon is mandatory when a clinical sign is mentioned, and early enucleation prevents an excessive destruction of bone. In this case, AOT was associated with the lateral maxillary incisor. e growth was slow over 18 months, which favors an early enucleation.

Conflicts of Interest
e authors declare that they have no con icts of interest.