Journal of Indian Academy of Oral Medicine and Radiology

: 2019  |  Volume : 31  |  Issue : 2  |  Page : 188--192

Plexiform ameloblastoma arising from the dentigerous cyst – A rare case report

Durga Okade, Tejavathi Nagaraj, IP Mahalakshmi, Swati Saxena 
 Department of Oral Medicine and Radiology, Sri Rajiv Gandhi College of Dental Sciences, Bengaluru, Karnataka, India

Correspondence Address:
Dr. Durga Okade
Department of Oral Medicine and Radiology, Sri Rajiv Gandhi College of Dental Sciences, Bengaluru - 560 032, Karnataka


Ameloblastoma, a benign epithelial odontogenic tumor, is locally aggressive. This tumor comprises about 1% of tumors and cysts arising in the jaws. It appears most commonly in the third to fifth decades and with equal frequency between sexes. They are usually benign in growth pattern but frequently invade locally and occasionally metastasize. Ameloblastoma prevalently occurs in the mandibular molar and the ramus areas. Recurrence frequently appears after inadequate treatment. Therefore, an appropriate diagnosis and treatment planning should be done to prevent the complications and for better prognosis. In this study, a case of plexiform ameloblastoma was presented with its clinical, radiological, histological features, and treatment modalities.

How to cite this article:
Okade D, Nagaraj T, Mahalakshmi I P, Saxena S. Plexiform ameloblastoma arising from the dentigerous cyst – A rare case report.J Indian Acad Oral Med Radiol 2019;31:188-192

How to cite this URL:
Okade D, Nagaraj T, Mahalakshmi I P, Saxena S. Plexiform ameloblastoma arising from the dentigerous cyst – A rare case report. J Indian Acad Oral Med Radiol [serial online] 2019 [cited 2019 Oct 21 ];31:188-192
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The term ameloblastoma was coined by Churchill in 1933, and the first detailed description of this lesion was given by Falkson in 1879. In the mandible (80% of ameloblastomas), 70% are located in the area of the molars or the ascending ramus, 20% in the premolar region, and 10% in the anterior region. Ameloblastoma is a true neoplasm of odontogenic epithelium.[1] It represents about 1% of all oral ectodermal tumors and 9% of odontogenic tumors.[2] Ameloblastoma is an aggressive neoplasm that arises from remnants of the dental lamina and odontogenic epithelium.[3],[4] Although most commonly it occurs in the third to fifth decades but the lesion can be seen in any age group including children.[5]

The common histopathological variants of ameloblastoma are follicular and plexiform types, followed by acanthomatous and granular cell types.[5] Ameloblastoma can be radiologically unilocular or multilocular radiolucency with a honeycomb/soap bubble appearance. Plexiform pattern is less aggressive and has a significantly lower recurrence rate.[6]

 Case Report

A 12-year-old girl reported to the Department of Oral Medicine and Radiology in 2016 with complaint of swelling on lower left back tooth region since last 6–7 months, which gradually increased in size. On extraoral examination [Figure 1], on inspection, solitary diffuse swelling seen on the left lower third of face, measuring ~2 × 3 cm in size, extending anteriorly from left corner of the mouth to 3 cm away from the left angle of the mandible, superio-inferior extent was 4 cm below the left ala-tragal line to inferior border of the mandible and on palpation, the swelling was hard in consistency and nontender. Intraoral soft tissue examination [Figure 2] revealed on inspection a diffuse solitary swelling on the buccal mucosa measuring ~2 × 4 cm in size, extending from mesial aspect of 41 to distal aspect of 75, crossing the midline, causing obliteration of labial and buccal vestibule. On palpation, buccal and lingual cortical plate expansion, the swelling was firm to hard in consistency and nontender. Intraoral hard tissue examination revealed the presence of overretained deciduous teeth 73 and 74. No physiological mobility was evident, and 33 and 34 were unerupted. The aspiration [Figure 3] was done under an aseptic condition at the site of swelling and straw colored fluid was obtained with spontaneous regression of the swelling [Figure 4]. On the basis of the clinical findings and aspiration, a provisional diagnosis of dentigerous cyst was given and clinical differential diagnosis given was ameloblastoma and central giant cell granuloma. OPG [Figure 5] revealed a well-defined large unilocular radiolucency, measuring ~4 × 5 cm in size on the left side of symphysis/ body region of the mandible surrounded by sclerotic border on the superior aspect of the radiolucency and in the inferior aspect of the lesion, scalloping was evident with 1 mm of inferior border of the mandible spared. The lesion was extending mediolaterally from distal aspect of 42, crossing the midline up to distal aspect of 75 and there was horizontal displacement of the 33 and 34 toward the lower border of the mandible. Radiographic diagnosis of dentigerous cyst was given and radiographic differential diagnosis was given as unicystic ameloblastoma.{Figure 1}{Figure 2}{Figure 3}{Figure 4}{Figure 5}

She had undergone marsupialization and the cystic lining was sutured. The histopathological examination revealed secondarily infected dentigerous cyst.

She reported back to us after 2 years (2018) with chief complaint of a similar swelling in the same region [Figure 6] since 3–4 months. On extraoral examination, there was minimal facial asymmetry. On intraoral soft tissue examination [Figure 7], the presence of solitary diffuse swelling on the left lower back tooth region, measuring ~2 × 5 cm in size, causing vestibular obliteration and extending from the distal aspect of 32 to the retro molar region. The swelling was partially covering the occlusal aspect of 35 and 37. On palpation, the swelling was nontender, firm to hard in consistency with expansion of buccal and lingual cortical plates. A working provisional diagnosis of ameloblastoma was given owing to the significant amount of the cortical plate expansion. Differential diagnosis of recurrent dentigerous cyst and panoramic radiography [Figure 8] showed a large multilocular radiolucent area occupying the left body of the mandible extending from mesial aspect of 44 crossing the midline up to the distal aspect of 34. There was a displacement of 33 and 34 near the left inferior border of the mandible and thinning of the inferior border of mandible sparing 1 mm of cortex. On the basis of the radiographic findings, a diagnosis was given as ameloblastoma.{Figure 6}{Figure 7}{Figure 8}

The histopathological examination revealed nonkeratinized stratified squamous odontogenic epithelium showing growth and projections into the cystic lumen. Epithelium also showed proliferation into the connective tissue capsule in a plexiform pattern with peripheral ameloblast-like cells and central stellate reticulum-like cells with positive margins at periphery. The final diagnosis was given as plexiform ameloblastoma with cystic changes.

The tumor mass was removed under general anesthesia with extraction of these teeth, i.e., 31, 32, 33, 34, 35, 41, 42, 43, and 44 [Figure 9], [Figure 10], [Figure 11]. She was recalled after 3 months for re-evaluation [Figure 11]. The wound healing was satisfactory. No recurrence has been reported till date.{Figure 9}{Figure 10}{Figure 11}


A dentigerous cyst is the most common cause of pericoronal radiolucency, which is associated with impacted teeth.[7] Because they are asymptomatic, dentigerous cysts are usually diagnosed on routine dental radiographs. The diagnosis of a dentigerous cyst is based on a combination of radiographic and histopathological features.[8] Dentigerous cysts form within the lining of the dental follicles when fluid accumulates within the follicular epithelium and the crown of developing or unerupted tooth.[9]

Dentigerous cyst most commonly manifests in teenage years as seen in our case, often developing around the crowns of unerupted teeth, but in our case, there was no pericoronal radiolucency rather there was a downward displacement of the permanent canine and the first premolar toward the lower border of the mandible showing the aggressiveness of the lesion. Till date, very few cases of ameloblastoma arising in the wall of dentigerous cyst have been reported similar to our case that was reported in a 12-year-old female patient.

An ameloblastoma is a benign and a locally aggressive tumor that arises from the mandible or less commonly, from the maxilla. Unicystic ameloblastomas are variants of ameloblastomas, which were first described by Robinson and Martinez. They refer to those cystic lesions that show clinical and radiological characteristics of odontogenic cysts, but in histological examination, and show typical ameloblastomatous epithelium that lies in a part of the cyst cavity, with or without a luminal or mural tumor proliferation.[10]

Ameloblastoma is a benign epithelial odontogenic tumor but it is often aggressive and destructive, with the capacity to attain great size, erode bone, and invade adjacent structures.[11] About 10%–15% of ameloblastomas are associated with a nonerupted tooth. In our case, a large plexiform ameloblastoma was found in the lower anterior region of the mandible crossing the midline and it was associated with a nonerupted tooth.

Worth (1963) divided ameloblastoma into 4 possible radiologic manifestations:

First category, there is a cyst-like cavity with some deficiency of the wall, and faint septa are observed within the lesion.

Second category has a gross caricature of a spider, which may be seen in some cases, i.e. pathognomonic of ameloblastoma.

Third pattern has a multilocular cystic appearance and is seen in the posterior portion of mandible and ramus.

Fourth category is associated with the solid variety of tumor. Normal bone is replaced with a honeycomb appearance in which cavities are relatively small and fairly uniform in size.

Our case falls into the first category of Worth's radiological manifestations.

According to World Health Organization, ameloblastomas can be classified into 4 groups: solid/multicystic, extraosseous/peripheral, desmoplastic, and unicystic.[12] Histopathologically, it occurs in 6 patterns: follicular, plexiform, acanthomatous, granular cell, basal cell, and desmoplastic type.[13]

Ameloblastoma appears equal frequency between sexes, although a higher frequency in females than in males has been described.[14] In our case, the patient was female and was in second decade of her life. Ameloblastoma frequently manifests as a painless swelling clinically, which can be accompanied by facial deformity, ulceration, malocclusion, periodontal disease, and paresthesia of the affected area. In our case, the clinical examination revealed a large expansile swelling in the anterior region of the mandible crossing the midline and extending posteriorly. The swelling was hard, covered by normal mucosa and painless to palpation. After the histopathological study, the tumor found in our patient was an ameloblastoma of the plexiform type. The term “plexiform” refers to the appearance of anastomosing islands of odontogenic epithelium in contrast to a follicular pattern. In a clinicopathological study done on 57 cases of unicystic ameloblastomas, Ackerson classified this entity into three histological groups: luminal unicystic ameloblastoma, intraluminal/plexiform unicystic ameloblastoma, and mural unicystic ameloblastoma. According to the above-mentioned entities, our case falls under the category of plexiform unicystic ameloblastoma.

In the second decade of life, various entities of similar radiographic features such as ameloblastic fibroma and unicystic or plexiform can be seen commonly, but the differentiation can only be made by the histopathological examination, which in our case finally reported as plexiform ameloblastoma with cystic changes, which is rare as compared to conventional unicystic ameloblastoma.[15]


Ameloblastoma is an aggressive tumor of odontogenic origin. Ameloblastoma should be studied carefully owing to the higher prevalence among odontogenic tumors with their biological behavior to detect the subtle changes in histology that may predict its aggressive behavior.

Treatment in our case was carried out only after biopsy results indicated plexiform ameloblastoma. The decisions regarding the treatment plan for ameloblastoma are based upon the patient's situation and the best judgment of the surgeon.

Early diagnosis of ameloblastoma should be done by oral physicians for a better treatment plan and good prognosis.

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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