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 Table of Contents  
Year : 2016  |  Volume : 28  |  Issue : 3  |  Page : 305-309

Extensive Type III unicystic ameloblastoma: A case report with conservative management

1 Department of Oral Medicine and Radiology, Faculty of Dental Sciences, Shree Guru Gobind Singh Tricentenary University, Gurgaon, Haryana, India
2 Department of Oral Medicine and Radiology, Vokkaligara Sangha Dental College and Hospital, Bengaluru, Karnataka, India
3 Department of Oral Medicine and Radiology, Lenora Institute of Dental Sciences, Rajahmundry, Andhra Pradesh, India

Date of Submission06-Oct-2015
Date of Acceptance30-Nov-2016
Date of Web Publication13-Dec-2016

Correspondence Address:
Dr. Astha Chaudhry
House No. 617, 1st Floor, Sector-9, Gurgaon - 122 001, Haryana
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0972-1363.195658

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Unicystic ameloblastoma is a distinct type of ameloblastoma that clinically and radiographically resembles a dentigerous cyst; however, on three-dimensional evaluation, it shows tumorous behavior and histopathologically shows ameloblastic epithelium. Compared to conventional ameloblastoma, it has a low recurrence rate after conservative treatment. We report a case of extensive unicystic ameloblastoma of mandible in a young male patient that showed tumorous characteristics on computed tomography (CT) and was treated conservatively by decompression. CT follow-up after 3 months showed significant bone formation. The lesion was then enucleated. Follow up at 8 months showed tremendous bone healing.

Keywords: Ameloblastoma, carnoy's solution, computed tomography

How to cite this article:
Chaudhry A, Muniraju M, Koduri S, Tanwar R. Extensive Type III unicystic ameloblastoma: A case report with conservative management. J Indian Acad Oral Med Radiol 2016;28:305-9

How to cite this URL:
Chaudhry A, Muniraju M, Koduri S, Tanwar R. Extensive Type III unicystic ameloblastoma: A case report with conservative management. J Indian Acad Oral Med Radiol [serial online] 2016 [cited 2022 Dec 3];28:305-9. Available from: http://www.jiaomr.in/text.asp?2016/28/3/305/195658

   Introduction Top

Ameloblastoma represents 13–54% of all jaw tumors.[1] It is a locally aggressive benign odontogenic neoplasm of epithelial origin. The source of epithelium may be enamel organ, remnants of dental lamina or Hertwig's epithelial root sheath, lining of odontogenic cysts or basal epithelial cells of oral mucosa. Ameloblastoma may present as three biologic variants, namely, solid/multicystic, unicystic, and peripheral.[2]

The unicystic variant was described by Robinson and Martinez in 1977.[3] It arises as a de novo neoplasm and not following secondary cystic changes in the solid counterpart.[4] The pathogenesis of completely cystic lesion is explained by epithelial dysadhesion i.e., defective desmosomes or due to the intrinsic production of enzymes such as metalloproteinase and serine proteinase that degrade the central zone of the enamel organ after tooth development.[5] Unicystic ameloblastoma radiographically appears similar to dentigerous cyst. However, the two can be differentiated following three-dimensional evaluation by computed tomography (CT) scan. In addition, CT helps in delineating the exact extent into the hard and soft tissues, guiding the best treatment. Histopathologically, unicystic ameloblastoma is categorized into three subtypes with distinct prognostic and therapeutic implications.[6]

This article presents a case of extensive unicystic ameloblastoma in the mandible of a young male patient, which on conventional radiography appeared to be a dentigerous cyst, but on CT and histopathologic examination, turned out to be unicystic ameloblastoma Type III. Usually, Type III lesions are treated aggressively, however, this case was treated conservatively by decompression, thus preventing esthetic and functional complications for the patient. The article also emphasizes the importance of CT in the diagnosis and follow-up of such lesions.

   Case Report Top

A 27-year-old male patient reported with a complaint of pain and swelling in the lower third of the face on the right side since 4 months. Swelling preceded the pain with associated history of occasional pus discharge from the mouth and reduction in mouth opening. No contributing medical history was reported. On extraoral examination, diffuse swelling was noted in the right middle and lower third of the face, with a smooth overlying surface, hard consistency, and tenderness on palpation, along with movable overlying skin. Mouth opening was 30 mm. Buccal cortical plate expansion was noted in the region of 44, 45, 46, and 47. Pus discharge was noted from the distal pocket of 47. Retromolar mucosa was tender on palpation. However, no lingual cortical plate expansion was noted.

A clinical diagnosis of an infected dentigerous cyst in relation to 48 was made. The patient was subjected to panoramic radiograph (OPG), CT, fine-needle aspiration cytology (FNAC) and routine blood investigations. OPG revealed a well-defined unilocular radiolucency surrounded by corticated borders associated with impacted 48 involving the right body, angle, ramus of the mandible that extended till the condylar process, sigmoid notch and coronoid process approximately measuring 6 × 9 cm. 48 was displaced apically and posteriorly to the angle of mandible. Cortical expansion and thinning was seen at the inferior border of mandible, sigmoid notch, ramus and the anterior border of ramus. External root resorption was seen in 45, 46, and 47 [Figure 1].
Figure 1: Orthopantomogram: Showing well-defined unilocular radiolucency in the right side of the mandible associated with impacted and displaced 48 and cortical expansion at the ramus, sigmoid notch, coronoid process, and inferior border of the mandible

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Axial section of the CT scan showed a unilocular lesion in association with impacted 48. The expansion of buccal as well as lingual cortex was appreciated. Cortical thinning and perforation was seen in the region of 46 [Figure 2]. The sagittal and coronal section showed the extent of the lesion in the angle, ramus, sigmoid notch, and coronoid process, along with expansion of the inferior border as well as cortical perforation in the inferior part. The apical and backward displacement of 48 was seen [Figure 3].
Figure 2: Computed tomography (axial section): Showing well-defined unilocular radiolucency with bicortical expansion and attachment of the lesion below the cementoenamel junction of 48

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Figure 3: Computed tomography (Sagittal and coronal sections): Showing the extent of ameloblastoma, cortical expansion, and perforation in the inferior part (arrow)

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Blood investigations showed values within normal limits. Aspiration yielded a cheesy material, and on microscopic examination, showed abundant mixed inflammatory cells consisting predominantly of neutrophils and few epithelial squames. Cytopathological features were suggestive of infected keratocyctic odontogenic tumor (KCOT) [Figure 4]a.
Figure 4: (a) Cytological smear: Showing inflammatory cells and epithelial squames (arrow). (b) Photomicrograph: Showing ameloblastic epithelium with hyperchromatic nuclei and stellate reticulum-.like cells

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The patient was subjected to conservative management. Envelope incision was given in the region of 45, 46, and 47; full thickness mucoperiosteal flap was reflected and 45, 46, and 47 were extracted under local anesthesia. The interradicular bone in the region of 45, 46, and 47 was trimmed and the extraction socket was curetted and a minute amount of cystic lining was excavated. A plastic suction tube was placed in the bony cavity and secured with stainless steel wire in relation to 44. Irrigation into the bony cavity [Figure 5] was performed with saline and betadine every alternate day under antibiotics and analgesics. Three-month follow-up CT scan revealed significant bone formation at the inferior border of mandible, at the inner surfaces of cortices, above the impacted tooth, and anteriorly in 44 region. The cortical perforations were repaired [Figure 6]. The lesion was then enucleated and carnoy's solution was applied for few minutes, followed by irrigation of the bony cavity.
Figure 5: Orthopantomograph: Showing the drain placed inside the lesion for decompression

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Figure 6: Follow up at 3rd month: Showing bone formation around the impacted tooth, thickening of the cortices, and repair of perforation at the inferior border (arrow)

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The enucleated specimen showed cystic epithelium comprising of tall columnar cells mimicking ameloblasts with hyperchromatic nuclei and stellate reticulum-like cells. Focal areas showed luminal proliferation of the epithelium in a plexiform pattern. Outer fibrous wall showed multiple ameloblastic islands with cystic degeneration, squamous metaplasia and areas of hyalinization. The histologic picture was suggestive of unicystic ameloblastoma Type III [Figure 4]b. The follow-up radiograph after 8 months showed significant bone formation anteriorly in the region of 45, at the angle, and inferior border of mandible, with significant reduction in the expansion of the inferior border [Figure 7]. The patient is on continued follow-up with continued irrigation of the bony cavity.
Figure 7: Follow up orthopantomograph at 8th month: Showing significant bone formation and reduction in cortical expansion

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   Discussion Top

Unicystic ameloblastoma accounts for approximately 10–15% of all ameloblastomas and presents as sharply demarcated monolocular radiolucency with a corticated border. At times, this monolocular radiolucency may show septae, and is usually associated with an impacted tooth in a pericoronal position. This appearance is similar to dentigerous cyst, adenomatoid odontogenic tumor (AOT), and KCOT. In our case, the same appearance was seen, and provisionally it was considered to be dentigerous cyst associated with impacted 48. However, with the CT scan it was appreciated that the pericoronal radiolucency was not attached to the cementoenamel junction (CEJ) of the involved tooth and was extended much lower down. The buccal cortex was expanded in tumorous fashion as the expanded cortex was making a smooth obtuse angle with normal cortex anteriorly and an abrupt acute angle with the unexpanded cortex posteriorly. The CT also showed bicortical expansion, which ruled out the possibility of dentigerous cyst. KCOT is classically known to run in anteroposterior direction, without causing significant cortical expansion, and rarely causes root resorption.[7] In our case, the FNAC report suggested the diagnosis of KCOT due to the presence of epithelial squames. However, that could be the result of squamous metaplasia seen in the cystic lining of ameloblastoma. AOT is uncommon in the posterior region.

The extent of the lesion and aspiration results in the present case demanded aggressive surgical treatment in the form of hemimandibulectomy. However, such aggressive treatment would result in loss of teeth, esthetics, and function, contributing to the reduced quality of life of patient. Considering these facts in addition to the patient's request and young age, conservative treatment was planned. The treatment options included enucleation, enucleation followed by carnoy's solution, marsupialization followed by enucleation, and marginal resection.[8] Because the lesion was extremely large, it was decided to reduce the lesion size by decompression followed by enucleation.

The patient responded well and CT showed good bone formation at third month. The lesion was enucleated and final diagnosis of unicystic plexiform ameloblastoma Type III was made. Type I lesions show unilocular cystic lesion with epithelium exhibiting features of ameloblastoma. Type II shows intraluminal extension of the epithelial nodules from cystic lining. In Type III, there is invasion of connective tissue wall of the cyst by islands of ameloblastomatous epithelium. Curettage is acceptable for luminal and intraluminal unicystic ameloblastoma because the tumor does not extend beyond the basement membrane of the cyst. Once the tumor invades into the wall of the cyst, it has a solid component which needs to be treated aggressively.[4]

In the present case, the type III lesion was treated conservatively by enucleation followed by carnoy's solution application for few minutes to minimize recurrence. Carnoy's solution (chloroform 3 ml, absolute alcohol 6 ml, glacial acetic acid 1 ml, ferric chloride 1 g) was initially described as a sclerozing agent for the treatment of cysts and fistulae.[9] Stoelinga and Bronkhorst in 1987 advocated its use after conservative treatment of unicystic ameloblastoma.[10] Lee et al.[11] also showed that use of carnoy's solution after enucleation of type III unicystic ameloblastoma results in lower recurrence rate.

The architectural pattern of ameloblastoma is such that the tumor extends into the cancellous bone beyond its apparent macroscopic surface and radiographic boundaries.[12] Marx et al.[13] showed that ameloblastoma cells penetrated approximately 2–8 mm into the trabecular spaces of bone beyond the apparent radiographic margin. Carnoy's solution has been shown to penetrate cancellous bone to a depth of 1.5 mm,[14] thereby fixing the residual ameloblastomatous tissue after enucleation diminishing the risk of recurrence. The prognosis of ameloblastoma is also dependent on the histologic type. The follicular, granular cell, and acanthomatous types have been shown to have a relatively high likelihood of recurrence, whereas the desmoplastic and plexiform types show a low potential for recurrence.[15],[16] In our case, plexiform type was noted, favoring conservative management.

   Conclusion Top

Unicystic ameloblastoma, despite being a low grade variant of ameloblastoma, may show aggressive behavior, especially the type III. Hence, this lesion should always be included in the differential diagnosis of swellings of the maxillofacial region. A thorough clinical, radiological, and histopathological evaluation must be performed to diagnose such lesions and plan the treatment accordingly. CT scan is indispensable in progressing toward an accurate diagnosis, to determine the extension, and to subsequently adapt the best treatment plan. It also helps in monitoring of bone formation and early diagnosis of recurrences. The choice of correct treatment should include consideration of age, type, anatomic extent, and histology of ameloblastoma. Conservative treatment should be the first choice in young patients for better quality of life. However, long-term follow up should be done for early diagnosis of recurrences and their management.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Reichart PA, Philipsen HP, Sonner S. Ameloblastoma: Biological profile of 3677 cases. Eur J Cancer B Oral Oncol 1995;31B: 86-99.  Back to cited text no. 1
Neville BW, Damm DD, Allen CM, Bouquot JE. Oral and Maxillofacial Pathology. 2nd ed. USA: W.B. Saunders; 2002. p. 611.  Back to cited text no. 2
Robinson L, Martinez MG. Unicystic ameloblastoma: A prognostically distinct entity. Cancer 1977;40:2278-85.  Back to cited text no. 3
Black CC, Addante RR, Mohila CA. Intraosseous ameloblastoma. Oral Surg Oral Med Oral Pathol Oral Radio Endod 2010;110:585-92.  Back to cited text no. 4
Rosenstein T, Pogrel MA, Smith RA, Regezi JA. Cystic ameloblastoma- Behaviour and treatment of 21 cases. J Oral Maxillofac Surg 2001;59:1311-6.  Back to cited text no. 5
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. 6
Langlais RP, Langland OE, Nortje CJ. Diagnostic Imaging of the Jaws. 2nd ed. Baltimore: Williams & Wilkins; 1995. p. 37, 331.  Back to cited text no. 7
Sampson DE, Pogrel MA. Management of mandibular ameloblastoma: The clinical basis for a treatment algorithm. J Oral Maxillofac Surg 1999;579:1074-7.  Back to cited text no. 8
Cutler EC, Zollinger R. Sclerosing solution in the treatment of cysts and fistulae. Am J Surg 1933;19:411-8.  Back to cited text no. 9
Stoelinga PJ, Bronkhorst FB. The incidence, multiple presentations and recurrence of aggressive cysts of the jaws. J Craniomaxillofac Surg 1988;16:184-95.  Back to cited text no. 10
Lee PK, Samman N, Ng IO. Unicystic ameloblastoma- Use of Carnoy's solution after enucleation. Intl J Oral Maxillofac Surg 2004;33:263-7.  Back to cited text no. 11
Ghandhi D, Ayoub AF, Pogrel MA, MacDonald G, Brocklebank LM, Moos KF. Ameloblastoma: A surgeon's dilemma. J Oral Maxillofac Surg 2006;64:1010-4.  Back to cited text no. 12
Marx RE, Smith BH, Smith BR. Swelling of the retromolar region and cheek associated with limited opening. J Oral Maxillofac Surg 1993;51:304-9.  Back to cited text no. 13
Voorsmit RA. The incredible keratocyst: A new approach to treatment. Dtsch Zahnarztl Z 1985;40:641-4.  Back to cited text no. 14
Hong J, Yun PY, Chung IH, Myoung H, Suh JD, Seo BM, et al. Long-term follow up on recurrence of 305 ameloblastoma cases. Intl J Oral Maxillofac Surg 2007;36:283-8.  Back to cited text no. 15
Ueno S, Mushimoto K, Shirasu R. Prognostic evaluation of ameloblastoma based on histologic and radiographic typing. J Oral Maxillofac Surg 1989;47:11-5.  Back to cited text no. 16


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

This article has been cited by
1 Role of Carnoy's solution as treatment adjunct in jaw lesions other than odontogenic keratocyst: a systematic review
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[Pubmed] | [DOI]


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