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 Table of Contents  
Year : 2020  |  Volume : 32  |  Issue : 3  |  Page : 315-319

Diagnostic dilemma of a silent tumor

1 Department of Oral Medicine and Radiology, Karpaga Vinayaga Institute of Dental Sciences, Kanchipuram, India
2 Department of Periodontics and Implantology, Karpaga Vinayaga Institute of Dental Sciences, Kanchipuram, India
3 Department of Oral Medicine and Radiology, Rajas Dental College and Hospital, Tirunelveli, India
4 Department of Oral Medicine and Radiology, Sri Venkateshwara Dental College, Puducherry, India

Date of Submission26-Aug-2019
Date of Decision26-Feb-2020
Date of Acceptance11-Jun-2020
Date of Web Publication29-Sep-2020

Correspondence Address:
Dr. Anisa Noorulla
Department of Oral Medicine and Radiology, Karpaga Vinayaga Institute of Dental Sciences, G. S. T. Road, Chinnakolambakkam, Palayanoor Post, Madhurandagam Taluk, Kanchipuram District, Kanchipuram – 603 308, Tamil Nadu
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jiaomr.jiaomr_153_19

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Ameloblastoma is a true neoplasm of odontogenic epithelium. It is a benign, persistent, aggressive, locally invasive tumor, capable of increasing in size and eroding bone. Unicystic ameloblastoma (UA) is a rare odontogenic tumor, which has unique clinical, radiographic, and histologic features of jaw tumors. The lesion histologically shows typical ameloblastomatous epithelium lining part of the cystic cavity with or without and/or mural tumor growth. This article reports a rare case of UA presenting as a multilocular lesion of a mandible in a 60-year-old female patient.

Keywords: Multilocular radiolucencies, odontogenic cyst/tumor, unicystic ameloblastoma

How to cite this article:
Noorulla A, Ramakrishna H, Murugan K, Paneerselvam D. Diagnostic dilemma of a silent tumor. J Indian Acad Oral Med Radiol 2020;32:315-9

How to cite this URL:
Noorulla A, Ramakrishna H, Murugan K, Paneerselvam D. Diagnostic dilemma of a silent tumor. J Indian Acad Oral Med Radiol [serial online] 2020 [cited 2020 Dec 3];32:315-9. Available from: https://www.jiaomr.in/text.asp?2020/32/3/315/296576

   Introduction Top

Dormant tumors are always found to be concealed by an impacted tooth. Ameloblastoma is a true neoplasm of the odontogenic epithelium (remnants of the dental lamina or dental organs).[1] It is a locally invasive tumor that originates from remnants of the dental lamina and odontogenic epithelium; accounts for only 1% of all oral tumors.[2],[3] Robinson defined ameloblastomas “usually unicentric, nonfunctional, intermittent in growth, anatomically benign and clinically persistent.”[4] Based on the World Health Organisation (WHO) classification of head and neck tumors, ameloblastoma has been classified into four types as multicystic, desmoplastic, unicystic, and peripheral.[5] The term Unicystic ameloblastoma (UA) refers to cystic lesions that show clinical, radiographic, and gross features of jaw cyst, but on histological examination shows a typical ameloblastomatous epithelium lining part of the cystic cavity with or without luminal and/or mural tumor growth.[6] UA was first described as a distinct entity by Robinson and Martinez in the year 1977.[7] Among ameloblastomas, the occurrence of UA is only about 6% and 50% of the cases occur in the second and third decade of life, predominantly in the posterior region of mandible.[8] Robinson and Martinez initially recommended conservative (enucleation and curettage) treatment, as it was thought to be different from solid and multicystic. Yet, its aggressive nature is explained in the recent emerging clinical evidences.[9] A brief review of UA is presented along with an interesting occurence of UA in a 60-year old female in posterior mandible as a multilocular radiolucency.

   Case Report Top

A 60-year-old female patient came with the chief complaint of pain and swelling in the left lower back teeth region of 3 months. Her history reveals that she had a toothache in the same region 3 months ago following which she developed swelling, for which she visited a private physician and had taken medication (unknown). Pain and swelling did not subside even after the medication. The swelling started insidiously as a peanut size and reached up to the present size. History revealed dull, continuous pain radiating to the ear. There was no history of trauma, fever, weight loss was reported. No history of bleeding or pus discharge or paraesthesia. Her medical and surgical histories were noncontributory. On clinical examination [Figure 1], asymmetry toward the left lower one-third of the face could be well appreciated. Presence of single diffuse swelling was evident with the left lower one-third of the face, measuring approximately 5 × 4 cm, extending superiorly from an imaginary line joining the corner of the mouth to the pinna of the ear inferiorly till the inferior border of the mandible. Anteriorly, it extended upto 1 cm from the left corner of the mouth till the angle of the mandible posteriorly. There was no color change on the surface of the swelling, the border appears to be diffused. No other secondary changes are evident. On palpation, all inspectory. findings such as site, size, shape, extent were confirmed. The swelling was bilobed, tender, with diffuse borders, firm to hard in consistency, compressible but not reducible. The skin over the swelling was pinchable. No parasthesia elicited.
Figure 1: Extraoral swelling on the left mandible

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On intraoral examination [Figure 2], there was a there is a single diffuse swelling seen to the left buccal vestibule measuring approximately 1.5 × 0.5 cm, that extended anteriorly from the mesial aspect of 36 to distal aspect of 38 posteriorly. The mucosa was intact with no sinus formation and borders were diffuse. There were no other secondary changes evident. On palpation, all inspectory findings were confirmed like site, size, shape, and extent. The lesion had diffuse borders, soft in consistency, tender on lingual aspect, and fluctuant concerning 36, 37 and egg shell cracking was present on the posterior aspect to 38. A provisional diagnosis of benign odontogenic cyst was made based on clinical findings. Differential diagnosis included odontogenic keratocystic tumor, ameloblastoma, central giant cell granuloma, and giant cell lesion of hyperparathyroidism.
Figure 2: Buccal cortical expansion on lower left molars

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On clinical investigations like electrical pulp testing of 34, 35, 36, 37, 38, a response in 38 was delayed and was nonvital. The lesion was aspirated, a 5 ml of straw color fluid was obtained from the lesion [Figure 3], which was sent to protein analysis, and the protein content of the cystic fluid was estimated to be 3.6 mg%. On radiographic examination [Figure 4]a IOPA revealed, well defined periapical radiolucencies concerning 36, 37, that has two distinct radiolucencies with complete loss of lamina dura and trabecular bone pattern with root resorption till one-third of the length of root apically, which gives the appearance of floating teeth and surrounded by sclerotic borders [Figure 4]b. The occlusal radiograph reveals the expansion of the lingual cortical plate concerning 36, 37, and 38 and thinning of the cortical plate with loss of trabecular bone pattern. OPG reveals bilocular radiolucency with loss of trabecular pattern and lamina dura with well-defined sclerotic borders and displacing the inferior alveolar canal inferiorly concerning the left angle of the mandibular region, suggestive of benign odontogenic tumor [Figure 5]. CBCT revealed multilocular hypodense areas with Hounsfield unit values between −70 to −176 corresponding to soft tissue density with perforation of buccal and lingual cortex and inferior displacement of mandibular canal but has intact cortical margins around it on the left side in favor of a benign lesion [Figure 6]a, [Figure 6]b, [Figure 6]c; these findings were suggestive of benign odontogenic tumor possibly either keratocystic odontogenic tumor or solid multicystic ameloblastoma.
Figure 3: FNAC showing 5 ml of straw color clear aspirate

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Figure 5: Orthopantomogram shows that bilocular well-defined radiolucency has multiple different shades of radiolucency with loss of trabecular pattern and lamina dura, root resorption surrounded by well-defined sclerotic borders with thinning of cortical bone posteriorly and displacing the inferior alveolar canal inferiorly

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Figure 6: (a-c) Axial, coronal, and 3D reconstruction images of CBCT showing multiple hypodense areas at the periapical region of 36, 37 with Hounsfield unit corresponding to soft tissues and has buccal and lingual cortical perforation

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Followed by incisional biopsy, H and E staining [Figure 7] a and [Figure 7]b showed areas of nonkeratinized stratified squamous epithelium with fibrovascular connective tissue. The epithelium is thin and uniform with intercellular edema. Focal areas show epithelium exhibiting tall columnar cells with reversal polarity and stellate reticular like cells. The underlying connective tissue shows hyalinized collagen fibers with fibroblasts and infiltrations of lymphocytes. Vascularity is moderate. These histopathological findings were suggestive of UA. Later the lesion was surgically excised and bone grafting was done. The excised specimen was also subjected to histopathological analysis, which confirmed the diagnosis of UA. The patient is under follow-up and no recurrence has been reported so far.
Figure 7:(a and b) Nonkeratinized stratified squamous epithelium with fibrovascular connective tissue, tall columnar cells with reversal polarity, and stellate reticular like cells. The underlying connective tissue shows hyalinized collagen fibers with fibroblasts

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   Discussion Top

The neoplasm was first described by Cusack in 1827.[6] Etymologically, the name derives from the old French word “amel,” which means enamel, and the Greek word “blastos,” meaning germ or bud. Over time, this tumor has been referred to by different names including “cystosarcoma,” “adamantine epithelioma,” “adamantinoma,” and finally “ameloblastoma.”[7] Ameloblastoma shows variable geographic prevalence, being the most common benign odontogenic tumor in China[8] and Africa,[9] while it is the second most common in the United States and Canada.[10] African Americans have an overall fivefold increased risk of disease as compared to Caucasians.[11] Global incidence has been estimated at 0.5 cases per million person-years, the neoplasm was first described by Cusack in 1827. The dilemma of concluding a UA is found to be high because of its profound and similar features of differential diagnosis. The UA mimics that of radicular cyst, dentigerous cyst, and odontogenic keratocyst. Detailed investigations must be done to rule out misdiagnosis. In both UA and dentigerous cyst, they are found to be involving the impacted tooth with unilocular radiolucencies. The occurrence of most of the odontogenic cyst and tumors is in the mandibular region involving the ramus and body of the mandible as slow-growing lesions. The commonest among these lesions are the radicular cyst, dentigerous cyst, odontogenic keratocyst (OKC), ameloblastomas, central giant cell granuloma (CGCG), and giant cell lesions of hyperparathyroidism. Radicular cyst presents usually as unilocular radiolucencies; in some cases, it appears as multilocular radiolucencies, especially involving anterior region; radiographic features are identical to those of other periapical multilocular radiolucencies. If untreated, the lesion slowly enlarges and expands the cortical plates.[10] Dentigerous cyst is associated with an unerupted tooth with unilocular radiolucencies and uniform loss of trabecular bone pattern, whereas in OKC multilocular radiolucencies contain curved/scalloped septa and tend to grow along with the bone with cortical expansion.[11] CGCG also appears as multilocular radiolucencies with cortical expansion leading to teeth migration and root resorption in 43% cases but occurs most commonly in young individuals.[10] Giant cell lesions of hyperparathyroidism occur as both unilocular and multilocular and found in patients with primary, secondary, and tertiary hyperparathyroidism which appear as poorly demarcated borders because of rarefied surrounding bone, and diagnosis depends on serum chemistry test.[10] The pathogenesis of cystic ameloblastoma is not clear. The reason why some ameloblastomas become completely cystic may be related to epithelial dysadhesion (e.g., defective desmosomes) or, more likely to the intrinsic production of proteinases, enzymes that normally degrade the central zone of enamel organ after tooth development.[11] The unicystic type of ameloblastoma is rare among ameloblastoma accounting for about 10%–15%.[12] Unicystic type appears more frequently in a younger population (third decade) than its solid counterpart.[13] In our case, the patient was 60 years old, which is uncommon for UA. The most common site of UA is posterior mandible followed by parasymphysis region, anterior maxilla, and posterior maxilla.[13] Based on histological examination, to diagnose a lesion as UA, the minimum criterion is the demonstration of the presence of a single cystic sac lined by odontogenic ameloblastomatous epithelium which is seen only in focal areas. There are different classifications of UA. Based on 57 cases of UA, Ackerman's classification into three histologic groups is as follows:

I. Luminal UA (tumor confined to the luminal surface of the cyst);

II. Intraluminal/plexiform UA (nodular proliferation into lumen without infiltration of tumor cells into connective tissue wall); and

III. Mural UA (invasive islands of ameloblastomatous epithelium in the connective tissue wall not involving the entire epithelium).[14]

According to this classification, our case study belongs to Group III.

There is another grouping by Philipsen and Reichart which describes the forms of UA as follows:

Subgroup 1. Luminal UA;

Subgroup 1.2. Luminal and intraluminal;

Subgroup 1.2.3. Luminal, intraluminal and intramural; and

Subgroup 1.3. Luminal and intramural.

The treatment should be in correlation with the histologic and clinical behavior of the lesion. UA is considered to be a less aggressive form of ameloblastomas that can be successfully removed by simple enucleation or other less aggressive surgery.[15] The growth pattern, the jaw in which the tumor is found, the age of the patient, and histopathologic subtypes are the most important factors when considering treatment options. Furthermore, the recurrence of UA may be delayed, and a long-term postoperative follow-up is essential for the proper management of these patients.

   Conclusion Top

Though ameloblastoma is benign in nature, it is aggressive in pathogenesis, locally invasive odontogenic tumors with a high rate of recurrence. Hence, whenever we come across multilocular radiolucencies, prudence to arrive at a correct diagnosis is important arrive at a correct diagnosis and prevent the complications at the earliest, as in our case we initially thought it to be ameloblastoma (less recurrence), later confirmed as unicystic (high recurrence) due to tumor penetration into adjacent tissue from the wall of the cyst. Very rarely, we come across multilocular and unicystic type in the same patient. This lesion was successfully treated with marsupialization and subsequent enucleation and this approach can be considered as an alternative to resection. Long-term follow-up is mandatory because of the recurrence risk of UA, which may occur after a long time.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Karjodkarn FR. Essentials of Oral and maxillofacial Radiology, First Edition. Jaypee Publication. p. 345.  Back to cited text no. 1
Piscevic A, Gavric M, Sjerobabin I. Maksilofacialna Hirurgija, Izdavacka Agencija “Draganic”, Beograd; 1995. p. 344-6.  Back to cited text no. 2
Li TJ, Kitano M. Reviewing the unicystic ameloblastoma: A clinicopathologically distinct entity. Oral Med Pathol 1997;2:61-8.  Back to cited text no. 3
Gerzenshtein J, Zhang F, Caplan J, Anand V, Lineaweaver W. Immediate mandibular reconstruction with microsurgical flap transfer following wide resection for ameloblastoma. J Craniofac Surg 2006;17:178-82.  Back to cited text no. 4
Kramer IRH, Pindborg JJ, Shear M. The World Health Organization histological typing of odontogenic tumors. A commentary on the 2nd Edition. Cancer 1992;70:2988-94.  Back to cited text no. 5
Li TJ, Wu YT, Yu SF, Yu GY. Unicysticameloblastoma: A clinicopathological study of 33 Chinese patients. Am J Surg Pathol 2000;24:1385-92.  Back to cited text no. 6
Robinson L, Martinez MG. Unicysticameloblastoma: A prognostically distinct entity. Cancer 1977;40:2278-85.  Back to cited text no. 7
Philipsen HP, Reichard PA. Unicysticameloblastoma. A review of 193 cases from the literature. Oral Oncol 1998;34:317-25.  Back to cited text no. 8
Lau SL, Samman N. Recurrence related to treatment modalities of unicystic ameloblastoma. A systematic review. Int. J. Oral Maxillofac Surg 2006;35:681-90.  Back to cited text no. 9
Wood NK, Goaz PW. Differential Diagnosis of Oral and Maxillofacial Lesions. 5th ed.. Elsevier Pub. p. 256-7.  Back to cited text no. 10
Olaitan AA, Adekeye EO. Clinical features and management of ameloblastoma of the mandible in children and adolescents. Br J Oral Maxillofac Surg 1996;34:248-51.  Back to cited text no. 11
Meetkamal KP. An unusual case of unicystic ameloblastoma involving the anterior of the maxilla. J Clin Diagn Res 2010;4:3659-63.  Back to cited text no. 12
Rosenstein T, Pogrel MA, Smith RA, Regezi JA. Cystic ameloblastoma – Behavior and treatment of 21 cases. J Oral Maxillofac Surg 2001;59:1311-6.  Back to cited text no. 13
Ackermann GL, Altini M, Shear M. The unicystic ameloblastoma: A clinicopathological study of 57 cases. J Oral Pathol 1988;17:541-6.  Back to cited text no. 14
Handa H, Bailoor DN, Naidu G, Shrivastava K, Raghuvanshi V. UnicysticAmeloblastoma of the mandible. Aggressive treatment A myth or a need. Case report and extensive review of the literature. IOSR J Dent Med Sci 2013;12:6-31.  Back to cited text no. 15


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]


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