Cyst or tumor in the buccomaxillary region: Review of literature and a case report.

Odontogenic tumors (OTs) include entities of a hamartomatous nature, such as odontoma, benign neoplasms like an adenomatoid odontogenic tumor (AOT), some benign neoplasms are aggressive as in the case of ameloblastoma. The AOT is a rare odontogenic tumor constituting only 3% of all the OT and very often misdiagnosed as an odontogenic cyst. We report a case of an intra-osseous type of AOT occurred in a young 16-year-old female located in the anterior maxilla along with the clinical, radiological, histological features, and literature review related to the tumor affecting the patient.

Neoplasms occurring in the buccomaxillary region affecting children and adolescents are most frequently benign.[1] Odontogenic tumors (OTs) comprise a large heterogenous group of lesions originating from the oral epithelium or from the odontogenic ectomesenchyme and their remains.[2] OT include entities of a hamartoma, such as odontoma, benign neoplasms some of which are aggressive as in the case of ameloblastoma and myxoma. Malignant neoplasms are capable of metastasis.[34] According to few studies OT account for only (1%) of oral lesions, whereas to others they account for (28%).[5]

Establishing comparisons among the reported data, the difference is due to the differences in the classification, criteria applied to diagnose and group of lesions, the upper age limit, and racial-ethnic origin of the population. Ameloblastoma, myxoma, ameloblastic fibro odontoma, cementoblastoma, ameloblastic fibroma, and calcifying epithelial OT were more frequently located in the posterior region of the mandible. Odontoma and adenomatoid odontogenic tumor (AOT) were more frequently located in the anterior region of the maxilla, whereas calcifying cystic odontogenic tumor was most frequently encountered in the posterior section of maxilla.[6]

According to the gender and age, OT like odontoma, myxoma, AOT, calcifying cystic OT, and calcifying epithelial OT showed equal or similar distribution according to the gender. All tumors types were more frequent in the second decade of life and some types such as cementoblastoma and calcifying epithelial OT, only presented in the second half of this decade.[6]

Case Report

A 16-year-old female patient had reported to the Department of Oral Medicine and Radiology with a chief complaint of a swelling and deformity associated with the right side of the face from past 1-week. The swelling was asymptomatic unnoticed earlier but had gradually increased in size from past 3 months.

On C/E - The swelling was painless nontender bony hard in consistency and immobile. The surface was smooth with well-defined edges. Intra oral - The swelling presented in the right maxillary region of buccal vestibule showing buccal cortical expansion, and missing right maxillary canine was noted [Figure 1]. On palpation the swelling was nontender, firm to hard in consistency with obliteration of buccal vestibule, positive crepitation was felt over palpating the posterior region of the swelling in relation to the teeth 14 and 15. Topographic right lateral maxillary occlusal projection revealed buccal cortical expansion associated with well-defined thin ostotic border in relation to the teeth [Figure 2]. Orthopantomogram showed obliteration of right maxillary sinus, root divergence,[78] and a well-defined radiolucent lesion with hyperostotic border associated with impacted canine[9] [Figure 3].

Figure 1

Cortical expansion and missing canine

Figure 2

Impacted canine with buccal cortical expansion associated with well-defined thin ostotic border

Figure 3

Impacted canine with obliteration of right maxillary sinus

Based on the clinical findings and radiological findings a provisional diagnosis of dentigerous cyst associated with an impacted tooth was given. Differential diagnosis such as AOT, odontoma, globulomaxillary cyst, calcifying epithelial odontogenic cyst, calcifying epithelial OT, unicystic ameloblastoma, central giant cell granuloma, and fibrous dysplasia were given.

A red color fluid resembling blood and blood products was obtained on aspiration. After routine blood examination like Hg, bleeding time, and clotting time, the lesion was approached under local anesthesia. The buccal flap was raised, thin cortical border was exposed and the tumor was excised along with the tooth and sent for histopathological examination [Figures 4 and 5].

Figure 4

Tumor excision with elevation of the thin cortical border

Figure 5

The excised tumor associated with the tooth (Canine)

The Hematoxylin and eosin stained section (×4) revealed cuboidal to columnar tumor cells arranged in the form of rosettes pattern. Cystic component were evident at the periphery of the lesion. The major part of tumor was solid demonstrating whorled arrangement of cells, at places the lesional tumor cells were arranged in strand like configuration in plexiform pattern [Figure 6]. However, the ductular pattern though the present was minimal [Figure 7]. Foci of dense extravasated red blood cell were seen in few areas and some amount of homogenous eosinophilic material (tumor droplets) was also present which confirms the diagnosis of AOT.

Figure 6

Tumor cells showing rosettes pattern, plexiform pattern and the cystic components present at the periphery of the lesion

Figure 7

Tumor cells proliferating in form of ductal pattern

Discussion

An uncommon distinct odontogenic neoplasm by name AOT was first described by Steensland[10] in 1905. In 1907, Driebladt[11] described AOT as a pseudoadenoma adamantinoma. The term cystic adamantinoma was reported by Harbitz[12] in 1915, where he linked this terminology to AOT. Stafne[13] in 1948 considered it as a distinct entity and not associated with ameloblastoma.

Bernier and Tiecke[14] were first to report a case on adenoameloblastoma. Philipsen and Birn[7] in 1969 coined the term AOT, and made it clear that the tumor is not related to any variety of ameloblastoma. Later in the year 1971, the WHO[9] accepted AOT in the category of first WHO classification of OT.

Unal et al.[8] listed a variety of nomenclatures for AOT. Earlier the tumor was known as adenoameloblastoma, ameloblastic adenomatoid tumor, adamantinoma, epithelioma adamantinum, and lastly teratomatous odontoma.

The current WHO[15] classification of OT related to histological typing in 2005, defines AOT as being composed of odontogenic epithelium in a variety of histoarchitectural patterns, embedded in a mature connective tissue stroma, and characterized by slow but progressive growth. The lack of evidence over the histogenesis of AOT, it is still not clear whether the AOT represents a hamartomatous growth or a true benign neoplasm.

The tumor appears as an intraoral-extraoral swelling in the maxilla, thus, sometimes known as “two third tumor.” Because, most of the two out of three cases involve maxilla, frequently affected gender were young females, always associated with unerupted tooth, and most commonly affected teeth are, the canines.[16]

The origin of AOT is still a debatable issue. However, few authors admit that the tumor could be derived from epithelial remnants of the dental lamina complex system. Thus, making the statement more complex with lack of clarity.[16]

According to Philipsen et al.[17] Follicular type is the most common (78%) associated with an unerupted or impacted tooth (basically canine), mimicking dentigerous cyst. The extrafollicular variant (24%) might occur intedentally or periapical to the teeth. The third and most infrequent (3%) is the peripheral form, generally affect the gingiva and quit frequently confused with fibrous epulis or gingival fibroma.

Females are affected by AOT more than males with a ratio of (1.9:1). Highest female incidence of AOT observed in Asian population such as Sri Lanka (3.2:1) and Japan (3:1).[18]

Clinically, AOT presents as a slow growing symptom free lesion and is frequently discovered during routine radiographic examination. AOT can occur in both intraosseous and extra osseous forms.

The follicular (intraosseous) type is the most frequent growth type of AOT. In this type, the tumor is localized around the crown of a retained tooth and additionally may cover the upper part of the distal root. In our case, the cyst like tumor covered the tooth completely giving access to the hard tissues after intended incision of the excised specimen.[17]

The gross appearance of the tumor is in accordance with former definitions of the entity recommended by the WHO.[15] The AOT may be “party cystic and in some cases the solid lesion may be present only as masses in the wall of a large cyst.”

On radiographs, the intraosseous follicular variant of AOT shows a well-defined, unilocular radiolucency surrounding the crown of a retained tooth. Indeed, the radiological findings in our case share similarities of other odontogenic lesions like a dentigerous cyst, unicystic ameloblastoma, or any periapical disease.

Minute radiopacities around the retained tooth may be found in AOT and are considered a characteristic but not pathognomonic finding, about two out of three AOT show distinct radiopaque calcifications on a radiograph.[19] These minute radiopacities are often seen better with periapical radiographs, as in our case no such features were noticed.

The extrafollicular variant shows well-defined radiolucent lesion located between, above or superimposing the root of an unerupted tooth. Finally, slight erosion of the underlying alveolar bone cortex might be detected in the gingival with peripheral or extra osseous type of AOT.[20]

WHO has described the histological features of the tumor as “a tumor of odontogenic epithelium” with duct-like structures and with varying degree of inductive changes in the connective tissue. The tumor may be partly cystic and in some cases the solid lesion may be present only as masses in the wall of a large cyst. It is generally believed that the lesion is not a “neoplasm.” Moreover, eosinophilic, uncalcified, amorphous material can be found and is called “tumor droplets.”[1617]

The histological association of AOT and dentigerous cyst was reported by Murali et al. He listed a case of AOT being developed in the fibrous capsule of the dentigerous cyst. Garcia-Pola et al. listed on one case, and reported the proliferation of adenomatoid odontogenic cyst in the epithelial border of a dentigerous cyst.[21]

Treatment and prognosis

Conservative approach by means of surgical enucleation or curettage is the treatment of choice. Giansanti et al. reported after he followed a number of cases from 1 to 10 years, showed the absence of recurrence after local curettage of the tumor.[19]

For periodontal intrabony defects caused by AOT, guided tissue regeneration with membrane technique is suggested after complete removal of the tumor. Recurrence rate of AOT is rare, but only a few cases from Japan were noted.[22]

Conclusion

Adenomatoid odontogenic tumor is relatively an uncommon benign odontogenic lesion that affects young patients in second decade, with a female predominance. AOT frequently mimick other odontogenic lesions such as dentigerous cyst or unicystic ameloblastoma. Radiographically when compared with dentigerous cyst, the radiolucency in AOT involves the entire length of the tooth and associated with minute radiopacities. The availability of modern research studies of DNA microarray analysis, in situ hybridization, genetic analysis, and other molecular biological techniques, the ways are opening up to solve the remaining confusions regarding the origin of AOT.