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Year : 2020  |  Volume : 9  |  Issue : 5  |  Page : 2524-2527  

Mural Unicystic Ameloblastoma mimicking Odontogenic Cyst

1 Department of Oral Pathology and Microbiology, Karpaga Vinayaga Institute of Dental sciences, Kanchipuram, Tamilnadu, India
2 Department of Oral and Maxillofacial Pathology, Meenakshi Ammal Dental College and Hospital, Chennai, Tamilnadu, India
3 Department of Oral and Maxillofacial Surgery, S.R.M. Dental College and Hospital, Chennai, Tamilnadu, India
4 Oral and Maxillofacial Surgery, Meenakshi Ammal Dental College and Hospital, Chennai, Tamilnadu, India

Date of Submission29-Jan-2020
Date of Decision13-Mar-2020
Date of Acceptance08-Apr-2020
Date of Web Publication31-May-2020

Correspondence Address:
Dr. Karthika Panneerselvam
Karpaga Vinayaga Institute of Dental sciences, Chinna Kolambakkam, Kanchipuram, Madurantagam, Tamil Nadu 603 308
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jfmpc.jfmpc_178_20

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Unicystic ameloblastoma is considered a less aggressive variant of ameloblastoma with clinical and radiographic features mimicking a cyst. Herein, we present a case of unicystic ameloblastoma in a 20-year-old female who was clinically and radiographically diagnosed as an odontogenic cyst. Unicystic ameloblastoma and its subtypes are reviewed with special emphasis on the mural variant. The main aim of this case report is to highlight (1) the need of including an odontogenic tumor in the differential diagnosis of the unilocular, well-circumscribed radiolucent lesion by the clinicians (2) importance of serial sectioning of the specimen to identify the mural component if any present, and (3) following resection as the mode of treatment.

Keywords: Mural ameloblastoma, odontogenic cyst, unicystic ameloblastoma

How to cite this article:
Panneerselvam K, Kavitha B, Panneerselvam E, Parameswaran A. Mural Unicystic Ameloblastoma mimicking Odontogenic Cyst. J Family Med Prim Care 2020;9:2524-7

How to cite this URL:
Panneerselvam K, Kavitha B, Panneerselvam E, Parameswaran A. Mural Unicystic Ameloblastoma mimicking Odontogenic Cyst. J Family Med Prim Care [serial online] 2020 [cited 2021 Mar 7];9:2524-7. Available from: https://www.jfmpc.com/text.asp?2020/9/5/2524/285084

  Introduction Top

Unicystic ameloblastoma (UA) is an odontogenic tumor but resembles a cyst clinically and radiographically. Its gross specimen features also resemble a cyst. Histologically, it exhibits ameloblastic epithelium lining a cystic cavity. The lining epithelium is accompanied with or without luminal and/or mural tumor growth.[1] UA was categorized as a separate group by Martinez and Robinson.[2] The lesion UA arises from reduced enamel epithelium or a dentigerous cyst or from solid ameloblastomas that undergo cystic degeneration.[3] UA was grouped by Philipsen and Reichart as luminal (subgroup 1); luminal and intraluminal (subgroup 1.2.); luminal, intraluminal, and intramural (subgroup 1.2.3); luminal and intramural (subgroup 1.3).[4]

  Case Presentation Top

A 20-year-old female patient came to the outpatient clinic with a chief complaint of painful swelling inside the mouth in the right lower back tooth region for about 3 months. History revealed that the swelling was initially small in size and had gradually increased to the present size. The pain was intermittent and dull and the patient was under medication.

On extraoral examination, no swelling was noticed and the mouth opening was normal. There were no signs of paresthesia in the lower lip. On intraoral examination, a swelling measuring 4 × 3 cm was noticed in the buccal aspect of 45 to 47 region obliterating the gingivobuccal sulcus with lingual cortical expansion. There was no associated discharge. Tooth 48 was clinically not present. On palpation, the swelling was tender with eggshell crackling. On fine-needle aspiration, blood-tinged fluid was obtained.

Orthopantomogram [Figure 1] revealed a unilocular well-circumscribed radiolucency with sclerotic border measuring 3 × 3.5 cm extending from the mesial root of 46 till the mesial root of 47. Inferiorly, the lesion extended 0.5 cm above the lower border of the mandible while 48 was absent. Absence of impacted tooth (48) and features like buccolingual cortical expansion, unilocular radiolucency together with the absence of cheesy, yellow aspirate ruled out the possibility of the dentigerous cyst, and odontogenic keratocyst.
Figure 1: Panoramic radiograph representing well-defined unilocular radiolucent lesion in the right mandible concerning 46 and 47

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An incisional biopsy on histopathological examination exhibited cystic lining epithelium associated with the connective tissue wall. The basal cells of the cystic lining epithelium were hyperchromatic with stellate reticulum like cells superficially. The lesion was histologically diagnosed as cystic ameloblastoma.

The patient was planned for a segmental resection with continuity defect and reconstruction with non-vascularized iliac crest bone graft under general anesthesia.

Grossly, a cut section across the resected specimen of bone revealed a unicystic lesion [Figure 2]. Histopathology revealed cystic lining epithelium in association with connectives tissue wall [Figure 3], [Figure 4], [Figure 5]. The lining epithelium exhibited hyperchromatic basal cells and loose stellate reticulum-like cells on the surface. In the connective tissue wall, and ameloblastic follicle with tall columnar peripheral cells exhibiting subnuclear vacuolization and central stellate reticulum with areas of cystic degeneration was seen. Correlating the clinical, radiographic, gross, and histopathology features, the lesion was concluded as UA of mural type. (Subtype 1.3).
Figure 2: Gross specimen of the lesion

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Figure 3: Photomicrograph showing cystic lining epithelium with connective tissue wall. (H and E staining, 4×)

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Figure 4: Photomicrograph shows ameloblastic island as follicle in the connective tissue. (H and E staining, 10×)

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Figure 5: Photomicrograph showing peripheral cells exhibiting reversal of polarity, hyperchromatic nuclei with stellate reticulum in the islands. Areas of cystic degeneration also present (H and E stain, 40×)

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  Discussion and Literature Review Top

UA subgroups with mural component are considered as the most aggressive type.[5]

It represents 10%–15% of ameloblastomas[2] and manifests commonly from 11 to 30 years of age with equal gender predilection.[2] Majority of the lesions are associated with an impacted tooth (dentigerous type) and others are non-dentigerous type. Smaller lesions are asymptomatic while larger lesions result in facial asymmetry and in some cases ulceration of the overlying mucosa.[6] The most frequent site of occurrence is the posterior mandible.[1],[2] The ratio of occurrence in maxilla and mandible is 1: 7 (dentigerous type) and 1: 4.7 (non-dentigerous type).[7]

Rarely UA mural type has been associated with varied histological features. UA (subgroup 1.2.3) with mural proliferation exhibiting follicular and acanthomatous patterns along with desmoplastic type have been recorded.[5] Though on incisional biopsy the case was diagnosed as cystic ameloblastoma the lesion was typed as UA only after excisional biopsy.[2] The segmentally resected mandible on gross examination encompassed a unicystic lesion signifying the importance of gross examination before typing the lesion as unicystic as some solid-multicystic ameloblastomas can also have areas of cystic degeneration.

It is important to note that in this case only upon histological examination of the excisional specimen the ameloblastic follicle was seen in the connective tissue wall and the lesion was identified as subgroup 1.3. Since the subgroups with the mural component are aggressive and their recurrence is 35.7%,[4],[5] it is suggested that unless UA lesions are extensive and pose esthetic problems in young patients, resection can be employed as the line of treatment than enucleation and marsupialization to prevent recurrence and second surgery.

The subtypes with the mural component are the most aggressive type of UA.[5] Increased expression of CD 34, MMP 2, and MMP 9 in the mural variant than in luminal and the intraluminal type explains the proliferative potential and the aggressiveness of the variant along with the necessity of radical treatment for the lesions.[8]

UA is treated by different methods like enucleation, marsupialization, and resection. Lower recurrence rate (3.6%) is observed with the resection method and highest (30.5%) with procedures employing enucleation.[9]

In a study of 116 cases of UA, recurrence associated with marsupialization was 12%. The study indicated that presence of mural histology in ameloblastoma, cortical bone resorption, or root resorption can imply aggressiveness of lesion which would result in recurrence following marsupialization in the early stage.[10]

  Conclusion Top

The main aim of the article is to emphasize that UA resembles a cyst clinically and radiographically, thus warranting its inclusion in the differential diagnosis of odontogenic cysts by the clinicians. Similarly, incisional and excisional biopsy specimens of UA should be subjected to periodic sampling and serial sectioning to determine the presence or absence of mural component. This will enable precise diagnosis of the lesion and will also facilitate the surgeons to decide on the treatment plan. Aggressive treatment like resection should be considered to prevent repeated surgeries. Post surgically, cases of mural UA should be reviewed periodically for recurrences.

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.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Paikkatt VJ, Sreedharan S, Kannan VP. Unicystic ameloblastoma of the maxilla: A case report. J Indian Soc Pedod Prev Dent 2007;25:106-10.  Back to cited text no. 1
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Singh A, Shaikh S, Samadi FM, Shrivastava S, Verma R. Maxillary unicystic ameloblastoma: A review of the literature. Natl J Maxillofac Surg 2011;2:163-8.  Back to cited text no. 2
[PUBMED]  [Full text]  
Figueiredo NR, Meena M, Dinkar AD, Malik S, Khorate M. Unicystic Ameloblastoma Presenting as a Multilocular Radiolucency in the Anterior Mandible: A Case Report. J Dent Res Dent Clin Dent Prospect 2015;9:199-204.  Back to cited text no. 3
Chaudhary Z, Sangwan V, Pal US, Sharma P. Unicystic ameloblastoma: A diagnostic dilemma. Natl J Maxillofac Surg 2011;2:89-92.  Back to cited text no. 4
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Mahadesh J, Rayapati DK, Maligi PM, Ramachandra P. Unicystic ameloblastoma with diverse mural proliferation – A hybrid lesion. Imaging Sci Dent 2011;41:29-33.  Back to cited text no. 5
Nagalaxmi V, Sangmesh M, Maloth KN, Kodangal S, Chappidi V, Goyal S. Unicystic mural ameloblastoma: An unusual case report. Case Rep Dent 2013;2013:957418.  Back to cited text no. 6
Nadendla LK. Unusual imaging appearance of unicystic ameloblastoma. Contemp Clin dent 2012;3:475-7.  Back to cited text no. 7
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Sah P, Menon A, Kamath A, Chandrashekar C, Carnelio S, Radhakrishnan R. Role of Immunomarkers in the clinicopathological analysis of unicystic ameloblastoma. Dis Markers 2013;35:481-8.  Back to cited text no. 8
Ramesh RS, Manjunath S, Ustad TH, Pais S, Shivakumar K. Unicystic ameloblastoma of the mandible – An unusual case report and review of literature. Head Neck Oncol 2010;2:1.  Back to cited text no. 9
Zheng CY, Cao R, Hong WS, Sheng MC, Hu YJ. Marsupialisation for the treatment of unicystic ameloblastoma of the mandible: A long term follow up of 116 cases. Br J Oral Maxillofac Surg 2019;57:655-2.  Back to cited text no. 10


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]


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