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Ameloblastoma arising in a dentigerous cyst: Report of three cases
Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology 26 (2014) 233–237
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Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology journal homepage: www.elsevier.com/locate/jomsmp
Case Report
Ameloblastoma arising in a dentigerous cyst: Report of three cases P.V. Nimonkar a,∗ , S.V. Nimonkar a , G.P. Mandlekar a , R.M. Borle b , A.R. Gadbail b a b
VSPM Dental College & Research Centre, Nagpur, India Sharad Pawar Dental College, Sawangi, Wardha, India
a r t i c l e
i n f o
Article history: Received 11 May 2011 Received in revised form 19 June 2012 Accepted 17 July 2012 Available online 10 September 2012 Keywords: Unicystic ameloblastoma Dentigerous cyst Dentigerous varient of unicystic ameloblastoma
a b s t r a c t We report three cases of ameloblastoma arising in the wall of dentigerous cysts. All the three cases had clinical and radiographic appearance similar to that of dentigerous cyst and were histologically proven to be dentigerous cyst on incisional biopsies. Intraoral enucleation and chemical cauterization was performed for all the three. Postoperative excisional biopsy revealed mural changes in the cystic lining of all the three cases. There was no further evidence of tumor over the following 7 years. The purpose of this paper is to highlight the fact that the lesions which appear as dentigerous cyst may have component of ameloblastic changes in the lining. © 2012 Asian AOMS, ASOMP, JSOP, JSOMS, JSOM, and JAMI. Published by Elsevier Ltd. All rights reserved.夽
1. Introduction The dentigerous cyst (DC) is often considered to be a docile lesion but possess an unusual ability to undergo metaplasia [1]. True neoplasms are known to develop in the cystic lining of dentigerous cyst such as ameloblastoma and adenomatoid odontogenic tumor. However, malignant transformation is considerably less common probably the rarest transformation is to ameloblastic carcinoma [2]. The malignancy most often associated with dentigerous cysts is squamous cell carcinoma and mucoepidermoid carcinoma [1]. Cahn in 1933 was the first to report a case of ameloblastoma originating in the wall of a dentigerous cyst [3]. Since then the development of an ameloblastoma in the wall of cyst has been the subject of number of publication. Although Vickers and Gorlin [4] has given a criteria to delineate histopathologically the transformation of cystic lining into the neoplasm, opinion differ among researchers regarding occurrence of this type of ameloblastoma. Three cases of ameloblastoma apparently arising in the walls of dentigerous cyst are presented to support this concept. 2. Case 1 A 12-year-old boy presented with a 2 week history of painful swelling in left mandibular region. He had history of incisional
夽 AsianAOMS: Asian Association of Oral and Maxillofacial Surgeons; ASOMP: Asian Society of Oral and Maxillofacial Pathology; JSOP: Japanese Society of Oral Pathology; JSOMS: Japanese Society of Oral and Maxillofacial Surgeons; JSOM: Japanese Society of Oral Medicine; JAMI: Japanese Academy of Maxillofacial Implants. ∗ Corresponding author at: Department of Oral & Maxillofacial Surgery, Faculty of Dentistry, VSPM Dental College & Research Centre, Nagpur, MS, India. Tel.: +91 9923800897 (mobile); fax: +91 9923800897. E-mail address: [email protected] (P.V. Nimonkar).
biopsy showing dentigerous cyst 13 months ago (Fig. 1). Intraoral examination showed a bony enlargement at the left buccal region extending from 33 to 36 region. The overlying mucosa was clinically normal (Fig. 2). Radiographic examination revealed a large unilocular radiolucency with well corticated margins involving impacted 33 (Fig. 3). Buccal decortication, enucleation of cyst and chemical cauterization of the defect with Carnoy’s solution was done. The tissue was sent for pathologic examination which revealed intramural proliferation of ameloblastous epithelium suggestive of unicystic ameloblastoma (UCA) type 1.3 (Fig. 4).
3. Case 2 A 25-year-old man reported to our Department for treatment of painful swelling of left side of face with approximately 2½ months of duration. Pain was dull, intermittent and was aggravated on mastication. Two years back incisional biopsy of the lesion from the same area revealed dentigerous cyst (Fig. 5 ). He could not undergo excision at that time due to personal reasons. No cervical lymphadenopathy was detected. Hypoesthesia was present on lower lip on left side. Intraoral examination revealed absence of 38 and ulceration on left retromolar region (Fig. 6). Radiographically a large unilocular radiolucency extending from 37 region to sigmoid notch with a thin margin of bone both on posterior border and inferior border of ramus of mandible. The radiolucency was well defined involving distoangularly impacted 38 (Fig. 7). Intraoral enucleation of cyst and chemical cauterization of the defect with Carnoy’s solution was done. Histopathology revealed ameloblastoma in the cystic lining with no evidence of infiltration in cortical bone suggestive of UCA type 1 (Fig. 8).
2212-5558/$ – see front matter © 2012 Asian AOMS, ASOMP, JSOP, JSOMS, JSOM, and JAMI. Published by Elsevier Ltd. All rights reserved.夽 http://dx.doi.org/10.1016/j.ajoms.2012.07.003
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P.V. Nimonkar et al. / Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology 26 (2014) 233–237
Fig. 1. Photomicrograph of incisional specimen showing features suggestive of dentigerous cyst (H&E ×400).
Fig. 4.
Fig. 2.
was referred to our unit. Past dental history revealed the evacuation of the contents of swelling and incisional biopsy. Microscopic diagnosis of the biopsy was dentigerous cyst performed 9 months ago (Fig. 9). Intraoral examination showed a bony hard swelling buccally in 37 region (Fig. 10). Radiographs revealed a large unilocular radiolucency involving distoangularly impacted 38 and causing expansion of ramus of mandible. The radiolucency was well defined extending from 37 region to sigmoid notch with thin rim of bone remaining on posterior border and inferior border of mandible (Fig. 11). Intraoral buccal decortication, enucleation of cyst and chemical cauterization of the defect with Carnoy’s solution was done and the tissue was sent for pathologic examination. Histopathology revealed proliferation of ameloblastoma in the cystic lumen suggestive of UCA type 1.2 (Fig. 12). Fig. 3.
5. Discussion 4. Case 3 A 25-year-old man, with a slow growing painless swelling of approximately 2 years’ duration over the left angle of mandible,
Fig. 5.
Unicystic ameloblastoma (UCA), a variant of ameloblastoma first described by Robinson and Martinez in 1977, refers to those cystic lesions that show clinical and radiographic characteristics of
P.V. Nimonkar et al. / Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology 26 (2014) 233–237
Fig. 6.
235
Fig. 10.
Fig. 11.
an odontogenic cyst but in histologic examination show a part of cystic cavity lined by typical ameloblastous epithelium, with or without luminal and/or mural tumor proliferations within the central type [5]. Also, tumors associated with an unerupted tooth are considered to be the dentigerous variant, whereas those lacking an association with an unerupted tooth were considered to be the non-dentigerous variant [5]. UCA is a rare type of ameloblastoma, accounting for about 6% of ameloblastomas. It usually occurs in a younger age group, with about 50% of the cases occurring in the second decade of life [6]. The dentigerous type occurs 8 years earlier on an average than the non dentigerous variant [7]. All our patients were below 30 years of age which is consistent with other studies. Stanley and Diehl, reviewed 641 cases of ameloblastoma, found that approximately 17% were definitely associated with an impacted tooth and/or a follicular cyst. They also noted a marked reduction in prevalence of such cases after the age of 30, presumably because of the loss of the ameloblastomatous potential of the odontogenic epithelium in the impacted tooth follicles and/or follicular cyst emphasizing the dangerous potential of the dentigerous cyst [8]. More than 90% of UCA are located in the mandible, with 77% located in the molar ramus region. They are most commonly encountered in the posterior mandible, followed by the
Fig. 7.
Fig. 8.
Fig. 9.
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P.V. Nimonkar et al. / Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology 26 (2014) 233–237
4. Subepithelial hyalinization.
Fig. 12.
parasymphysis region, anterior maxilla, and the posterior maxilla [9]. Between 50 and 80% of cases are associated with tooth impaction, the mandibular third molar being most often involved [7]. Patients most commonly present with swelling and facial asymmetry, pain being an occasional presenting symptom. Lesions frequently become large and destructive. Mucosal ulceration is rare but may be caused by continued growth of the tumor [7]. In the most comprehensive study on the radiographic aspects of UCA, it was found that the unilocular:multilocular ratio was 13:3 for cases associated with impacted teeth, against an almost equal 8:7 for the non dentigerous type [10]. Based on the series of 33 cases of the dentigerous variant of UCA, it was suggested that the involved tooth crown is displaced by the cystic tumor rather than being projected into cyst lumen [11]. The cases we have reported were typical in terms of clinical and radiographic features and corroborate the existing data. Dentigerous cysts, adenomatoid odontogenic tumor and unicystic ameloblastomas can be the possible differential diagnosis for a unilocular lesion with a ‘dentigerous’ relationship occurring within the jaw. However, adenomatoid odontogenic tumor has a predilection for anterior maxilla. UCAs and DCs are known to have a similar clinical and radiographic appearance. It is difficult to establish diagnosis between UCA and DC unless a whole of the lesion is presented before histological examination [7]. Similar difficulty was faced by us while diagnosing all our 3 present cases. In these reported cases of dentigerous variant of UCA, the period of interval varies from 13 months, 2 years and 9 months between the incisional biopsy and excisional biopsy for case 1, case 2 and case 3 respectively. This may not influence the metaplastic changes in dentigerous cyst as there is possibility of taking the incisional biopsy from the inappropriate area of the lesion. Various studies report that between 15 and 30% of all ameloblastomas form in the wall of a dentigerous cyst [12]. However, it is not known whether they arise from a neoplastic transformation of cells from an otherwise non neoplastic dentigerous epithelium or arise de novo [9]. The only inconvertible proof that a UCA originated in DC is demonstration of mural changes in the cystic lining, which the current cases demonstrates. It could be difficult to distinguish UCA from DC because their lining tends to become flat, losing typical ameloblastic epithelia due to cystic expansion [13]. However, following are the points used to distinguish between UCA and DC given by Vickers and Gorlin [4]. 1. Epithelial lining – parts may show transformation to cuboidal or columnar basal cells with hyperchromic nuclei. 2. Nuclear palisading with polarization. 3. Cytoplasmic vacuolation with intercellular spacing.
Many attempts have been made to establish specific immunohistochemical markers for ameloblastomas. For example, it has been suggested that differences in the expression of cell surface carbohydrates with blood group specificity may distinguish ameloblastomas from odontogenic cyst [14], although this hypothesis was not confirmed by other authors. Ki-67 and PCNA (proliferating cell nuclear antigen) are used to check the proliferative index of the UCA and found significantly more PCNA-positive cells in UCA than in DC lining [11]. An immunohistochemical evaluation of Ki-67 in DCs, UCAs, and ameloblastomas arising in DCs confirmed the hypothesis that an ameloblastoma arising from a DC has a similar biological behavior to that of UCA [15]. It has been suggested that calretinin is a specific immunohistochemical markers for neoplastic ameloblastic epithelium and may serve as a diagnostic tool for differentiating cystic odontogenic lesions from ameloblastic tumor [16]. Tsuneki et al. [13] suggested that six immunohistochemical markers K10, K13, K17, perlecan, PCNA and Ulex europaeus agglutinin-I lectin binding (UEA) were useful for distinction of the five cystic jaw lesions [UCA, Keratocystic odontogenic tumor (KCOT), Lateral periodontal cyst (LPC), DC and Radicular cyst (RC)] when their evaluation was combined. UEA is considered to be more specific amongst this six markers to differentiate UCA from KCOT, RC, LPC and DC. Recently, Masloub et al. [17] recommended that high CD10 and osteopontin expression in DC might predict the neoplastic potentiality of the epithelial lining of this cyst. Also, high CD10 and osteopontin expression in UCA might be a useful tool to identify areas with locally invasive behavior and high risk of recurrence. However; up to date, no general recommendations exist. Moreover, currently unaided histologic assessment for UCA remains the gold standard for diagnosis, because of a variable response of UCA to tissue markers. Although, UCAs with islands of ameloblastomatous epithelium may be misdiagnosed as a DC if no more than two histologic sections are examined [18]. Treatment is decided by the clinical behavior and which in turn is dictated by the histological pattern of the ameloblastoma. Based on histologic subgrouping provided by Philipsen and Reichart [6], our cases fall in subgroup 1.3, 1 and 1.2 for case 1, case 2 and case 3 respectively. Our findings are consistent with one study which showed that the mural variety is seen to be more often associated with the ‘non-dentigerous’ type of these lesions, while the intraluminal proliferations are more than twice as frequent in UCAs of the ‘dentigerous’ type [19]. The management of the cystic ameloblastomas remains controversial. We believe that these lesions generally represent a less aggressive type of ameloblastoma and therefore should have a better prognosis. However, they may well be too destructive and infiltrative in their behavior to respond predictably to local enucleation or curettage. The UCAs diagnosed as subgroups 1 and 1.2 can be treated by careful enucleation and the jaw bones salvaged, provided it is salvageable, whereas subgroups 1.2.3 and 1.3 showing intramural growths require radical treatment like resection, as for a solid or multicystic ameloblastoma. Following enucleation, vigorous curettage of the bone should be avoided as it may implant foci of ameloblastoma more deeply into the bone [6]. Chemical cauterization with Carnoy’s solution is also advocated for subgroup 1 and 1.2. The use of Carnoy’s solution to decrease chances of recurrence after conservative surgical treatment of UCAs was initially suggested by Stoelinga and Bronkhorst in 1988 and later many reported the success rate with the same [20]. Late recurrence following treatment is commonly seen, the average interval for recurrence being seven years. The overall recurrence rate of UCAs for all cases was 15%, with some evidence to suggest that the mural histologic subtype has a greater recurrence rate of 35.7% than the others only 6.7% [21]. Recurrence rates are
P.V. Nimonkar et al. / Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology 26 (2014) 233–237
also related to the type of initial treatment. Lau et al. [22] reported recurrence rates of 3.6% for resection, 30.5% for enucleation alone, 16% for enucleation followed by Carnoy’s solution application, and 18% by marsupialization followed by enucleation (where the lesion reduced in size). It is often the case that surgeons perform enucleation or excisional biopsy for a presumed dental cyst only to be informed later of the diagnosis of cystic ameloblastoma. The surgeon is then faced with determining whether the patient should undergo more aggressive treatment or to be closely followed with serial radiographs and clinical examinations. However if there is slight suspicion of the lesion being UCA, enucleation followed by treatment with either Carnoy’s solution or liquid nitrogen cryotherapy should be done, so that no further treatment is needed in case of type 1 and 1.2 UCAs. Whenever facilities for frozen section are available an attempt should be made to detect the ameloblastic changes if any so as to modify the surgical margins immediately in an attempt to improve the prognosis. It is pertinent to mention that whole specimen needs to be actively screened for mural invasion in every case of UCA to determine the histological subtype and treatment subsequently. If the histology yields the diagnosis of type 1.2.3 or 1.3, again marginal or partial resection would most aptly reduce the chance of any recurrence. All of our cases were treated by enucleation and prophylactic chemical cauterization, which were therapeutically enough for case 2 and case 3. However, in our case 1 (subtype 1.3), the child was small and resection would cause lots of morbidity, so we preferred follow up than resection. References [1] Yasouka T, Yonemoto K, Kato Y, Tatematsu N. Squamous cell carcinoma arising in dental cyst. J Oral Maxillofac Surg 2000;58:900–5. [2] TajimaY, Sakamoto E, Yammamoto Y. Odontogenic cyst giving rise to an adenomatoid odontogenic tumor-report of a case with peculiar features. J Oral Maxillofac Surg 1992;50:190. [3] Cahn LR. The dentigerous cyst as a potential adamantinoma. Dent Cosmos 1993;75:889.
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[4] Vickers RA, Gorlin RJ, Ameloblastoma:. Delineation of early histopathological features of neoplasia. Cancer 1970;26:699–710. [5] Robinson L, Martinez MG. Unicystic ameloblastoma: a prognostically distinct entity. Cancer 1977;40:2278–85. [6] Philipsen HP, Reichart PA. Unicystic ameloblastoma, Odontogenic tumors and allied lesions. London: Quintessence Pub. Co. Ltd.; 2004, pp. 77–86. [7] Roos RE, Raubenheimer EJ, Van Heerden WF. Clinico-pathological study of 30 unicystic ameloblastomas. J Dent Assoc S Afr 1994;49:559–62. [8] Stanley HR, Diehl DL. Ameloblastoma potential of follicular cysts. Oral Surg 1965;20:260–8. [9] Ackermann GL, Altini M, Shear M. The unicystic ameloblastoma: a clinicopathologic study of 57 cases. J Oral Pathol 1988;17:541–6. [10] Eversole LR, Leider AS, Strub D. Radiographic characteristics of cystogenic ameloblastoma. Oral Surg Oral Med Oral Pathol 1984;57:572–7. [11] Li TJ, Wu YT, Yu SF, Yu GY. Unicystic ameloblastoma: a clinicopathologic study of 33 Chinese patients. Am J Surg Pathol 2000;24:1385–92. [12] Wood NK, Kuc IM. Pericoronal radiolucencies. In: Differential diagnosis of oral and maxillofacial lesion. 5th ed. St. Louis: Mosby; 1997. [13] Tsuneki M, Yamazaki M, Cheng J, Maruyama S, Kobayashi T, Saku T. Combined immunohistochemistry for the differential diagnosis of cystic jaw lesions: its practical use in surgical pathology. Histopathology 2010;57:806–13. [14] Vedtofte P. Distribution of type 1 and 2 blood group chains in normal and pathological odontogenic epithelium defined by monoclonal antibodies specific for Lea and H type 2. Acta Pathol Microbiol Immunol Scand (A) 1985;93:265–76. [15] Piattelli A, Lezzi G, Fioroni M, Santinelli A, Rubini C. Ki-67 Expression in dentigerous cysts, unicystic ameloblastomas, and ameloblastomas arising from dental cyst. J Endod 2002;28:55–8. [16] Coleman H, Altini M, Ali H, Doglioni C, Favia G, Maiorano E. Use of calretinin in the differential diagnosis of unicystic ameloblastomas. Histopathology 2001;38, 408-312-7. [17] Masloub SM, Abdel-Azim AM, Abd Elhamid ES. CD10 and osteopontin expression in dentigerous cyst and ameloblastoma. Diagn Pathol 2011;6:44. [18] Dunsche A, Babendererde O, Luttges J, Springer ING. Dentigerous cyst versus unicystic ameloblastoma differential diagnosis in routine histology. J Oral Pathol Med 2003;32:486–91. [19] Philipsen HP, Reichart PA. Unicystic ameloblastoma. A review of 193 cases from the literature. Oral Oncol 1998;34:317–25. [20] Stoelinga PJW, Bronkhorst FB. The incidence, multiple presentation and recurrence of aggressive cysts of the jaws. J Craniomaxillofac Surg 1988;16:184–95. [21] Li TJ, Wu YT, Yu SF, Yu GY. Clinicopathological features of unicystic ameloblastoma with special reference to its recurrence. Zhonghua Kou Qiang Yi Xue Za Zhi 2002;37:210–2. [22] Lau SL, Samman N. Recurrence related to treatment modalities of unicystic ameloblastoma: a systematic review. Int J Oral Maxillofac Surg 2006;35:681–90.
Contents lists available at ScienceDirect
Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology journal homepage: www.elsevier.com/locate/jomsmp
Case Report
Ameloblastoma arising in a dentigerous cyst: Report of three cases P.V. Nimonkar a,∗ , S.V. Nimonkar a , G.P. Mandlekar a , R.M. Borle b , A.R. Gadbail b a b
VSPM Dental College & Research Centre, Nagpur, India Sharad Pawar Dental College, Sawangi, Wardha, India
a r t i c l e
i n f o
Article history: Received 11 May 2011 Received in revised form 19 June 2012 Accepted 17 July 2012 Available online 10 September 2012 Keywords: Unicystic ameloblastoma Dentigerous cyst Dentigerous varient of unicystic ameloblastoma
a b s t r a c t We report three cases of ameloblastoma arising in the wall of dentigerous cysts. All the three cases had clinical and radiographic appearance similar to that of dentigerous cyst and were histologically proven to be dentigerous cyst on incisional biopsies. Intraoral enucleation and chemical cauterization was performed for all the three. Postoperative excisional biopsy revealed mural changes in the cystic lining of all the three cases. There was no further evidence of tumor over the following 7 years. The purpose of this paper is to highlight the fact that the lesions which appear as dentigerous cyst may have component of ameloblastic changes in the lining. © 2012 Asian AOMS, ASOMP, JSOP, JSOMS, JSOM, and JAMI. Published by Elsevier Ltd. All rights reserved.夽
1. Introduction The dentigerous cyst (DC) is often considered to be a docile lesion but possess an unusual ability to undergo metaplasia [1]. True neoplasms are known to develop in the cystic lining of dentigerous cyst such as ameloblastoma and adenomatoid odontogenic tumor. However, malignant transformation is considerably less common probably the rarest transformation is to ameloblastic carcinoma [2]. The malignancy most often associated with dentigerous cysts is squamous cell carcinoma and mucoepidermoid carcinoma [1]. Cahn in 1933 was the first to report a case of ameloblastoma originating in the wall of a dentigerous cyst [3]. Since then the development of an ameloblastoma in the wall of cyst has been the subject of number of publication. Although Vickers and Gorlin [4] has given a criteria to delineate histopathologically the transformation of cystic lining into the neoplasm, opinion differ among researchers regarding occurrence of this type of ameloblastoma. Three cases of ameloblastoma apparently arising in the walls of dentigerous cyst are presented to support this concept. 2. Case 1 A 12-year-old boy presented with a 2 week history of painful swelling in left mandibular region. He had history of incisional
夽 AsianAOMS: Asian Association of Oral and Maxillofacial Surgeons; ASOMP: Asian Society of Oral and Maxillofacial Pathology; JSOP: Japanese Society of Oral Pathology; JSOMS: Japanese Society of Oral and Maxillofacial Surgeons; JSOM: Japanese Society of Oral Medicine; JAMI: Japanese Academy of Maxillofacial Implants. ∗ Corresponding author at: Department of Oral & Maxillofacial Surgery, Faculty of Dentistry, VSPM Dental College & Research Centre, Nagpur, MS, India. Tel.: +91 9923800897 (mobile); fax: +91 9923800897. E-mail address: [email protected] (P.V. Nimonkar).
biopsy showing dentigerous cyst 13 months ago (Fig. 1). Intraoral examination showed a bony enlargement at the left buccal region extending from 33 to 36 region. The overlying mucosa was clinically normal (Fig. 2). Radiographic examination revealed a large unilocular radiolucency with well corticated margins involving impacted 33 (Fig. 3). Buccal decortication, enucleation of cyst and chemical cauterization of the defect with Carnoy’s solution was done. The tissue was sent for pathologic examination which revealed intramural proliferation of ameloblastous epithelium suggestive of unicystic ameloblastoma (UCA) type 1.3 (Fig. 4).
3. Case 2 A 25-year-old man reported to our Department for treatment of painful swelling of left side of face with approximately 2½ months of duration. Pain was dull, intermittent and was aggravated on mastication. Two years back incisional biopsy of the lesion from the same area revealed dentigerous cyst (Fig. 5 ). He could not undergo excision at that time due to personal reasons. No cervical lymphadenopathy was detected. Hypoesthesia was present on lower lip on left side. Intraoral examination revealed absence of 38 and ulceration on left retromolar region (Fig. 6). Radiographically a large unilocular radiolucency extending from 37 region to sigmoid notch with a thin margin of bone both on posterior border and inferior border of ramus of mandible. The radiolucency was well defined involving distoangularly impacted 38 (Fig. 7). Intraoral enucleation of cyst and chemical cauterization of the defect with Carnoy’s solution was done. Histopathology revealed ameloblastoma in the cystic lining with no evidence of infiltration in cortical bone suggestive of UCA type 1 (Fig. 8).
2212-5558/$ – see front matter © 2012 Asian AOMS, ASOMP, JSOP, JSOMS, JSOM, and JAMI. Published by Elsevier Ltd. All rights reserved.夽 http://dx.doi.org/10.1016/j.ajoms.2012.07.003
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P.V. Nimonkar et al. / Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology 26 (2014) 233–237
Fig. 1. Photomicrograph of incisional specimen showing features suggestive of dentigerous cyst (H&E ×400).
Fig. 4.
Fig. 2.
was referred to our unit. Past dental history revealed the evacuation of the contents of swelling and incisional biopsy. Microscopic diagnosis of the biopsy was dentigerous cyst performed 9 months ago (Fig. 9). Intraoral examination showed a bony hard swelling buccally in 37 region (Fig. 10). Radiographs revealed a large unilocular radiolucency involving distoangularly impacted 38 and causing expansion of ramus of mandible. The radiolucency was well defined extending from 37 region to sigmoid notch with thin rim of bone remaining on posterior border and inferior border of mandible (Fig. 11). Intraoral buccal decortication, enucleation of cyst and chemical cauterization of the defect with Carnoy’s solution was done and the tissue was sent for pathologic examination. Histopathology revealed proliferation of ameloblastoma in the cystic lumen suggestive of UCA type 1.2 (Fig. 12). Fig. 3.
5. Discussion 4. Case 3 A 25-year-old man, with a slow growing painless swelling of approximately 2 years’ duration over the left angle of mandible,
Fig. 5.
Unicystic ameloblastoma (UCA), a variant of ameloblastoma first described by Robinson and Martinez in 1977, refers to those cystic lesions that show clinical and radiographic characteristics of
P.V. Nimonkar et al. / Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology 26 (2014) 233–237
Fig. 6.
235
Fig. 10.
Fig. 11.
an odontogenic cyst but in histologic examination show a part of cystic cavity lined by typical ameloblastous epithelium, with or without luminal and/or mural tumor proliferations within the central type [5]. Also, tumors associated with an unerupted tooth are considered to be the dentigerous variant, whereas those lacking an association with an unerupted tooth were considered to be the non-dentigerous variant [5]. UCA is a rare type of ameloblastoma, accounting for about 6% of ameloblastomas. It usually occurs in a younger age group, with about 50% of the cases occurring in the second decade of life [6]. The dentigerous type occurs 8 years earlier on an average than the non dentigerous variant [7]. All our patients were below 30 years of age which is consistent with other studies. Stanley and Diehl, reviewed 641 cases of ameloblastoma, found that approximately 17% were definitely associated with an impacted tooth and/or a follicular cyst. They also noted a marked reduction in prevalence of such cases after the age of 30, presumably because of the loss of the ameloblastomatous potential of the odontogenic epithelium in the impacted tooth follicles and/or follicular cyst emphasizing the dangerous potential of the dentigerous cyst [8]. More than 90% of UCA are located in the mandible, with 77% located in the molar ramus region. They are most commonly encountered in the posterior mandible, followed by the
Fig. 7.
Fig. 8.
Fig. 9.
236
P.V. Nimonkar et al. / Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology 26 (2014) 233–237
4. Subepithelial hyalinization.
Fig. 12.
parasymphysis region, anterior maxilla, and the posterior maxilla [9]. Between 50 and 80% of cases are associated with tooth impaction, the mandibular third molar being most often involved [7]. Patients most commonly present with swelling and facial asymmetry, pain being an occasional presenting symptom. Lesions frequently become large and destructive. Mucosal ulceration is rare but may be caused by continued growth of the tumor [7]. In the most comprehensive study on the radiographic aspects of UCA, it was found that the unilocular:multilocular ratio was 13:3 for cases associated with impacted teeth, against an almost equal 8:7 for the non dentigerous type [10]. Based on the series of 33 cases of the dentigerous variant of UCA, it was suggested that the involved tooth crown is displaced by the cystic tumor rather than being projected into cyst lumen [11]. The cases we have reported were typical in terms of clinical and radiographic features and corroborate the existing data. Dentigerous cysts, adenomatoid odontogenic tumor and unicystic ameloblastomas can be the possible differential diagnosis for a unilocular lesion with a ‘dentigerous’ relationship occurring within the jaw. However, adenomatoid odontogenic tumor has a predilection for anterior maxilla. UCAs and DCs are known to have a similar clinical and radiographic appearance. It is difficult to establish diagnosis between UCA and DC unless a whole of the lesion is presented before histological examination [7]. Similar difficulty was faced by us while diagnosing all our 3 present cases. In these reported cases of dentigerous variant of UCA, the period of interval varies from 13 months, 2 years and 9 months between the incisional biopsy and excisional biopsy for case 1, case 2 and case 3 respectively. This may not influence the metaplastic changes in dentigerous cyst as there is possibility of taking the incisional biopsy from the inappropriate area of the lesion. Various studies report that between 15 and 30% of all ameloblastomas form in the wall of a dentigerous cyst [12]. However, it is not known whether they arise from a neoplastic transformation of cells from an otherwise non neoplastic dentigerous epithelium or arise de novo [9]. The only inconvertible proof that a UCA originated in DC is demonstration of mural changes in the cystic lining, which the current cases demonstrates. It could be difficult to distinguish UCA from DC because their lining tends to become flat, losing typical ameloblastic epithelia due to cystic expansion [13]. However, following are the points used to distinguish between UCA and DC given by Vickers and Gorlin [4]. 1. Epithelial lining – parts may show transformation to cuboidal or columnar basal cells with hyperchromic nuclei. 2. Nuclear palisading with polarization. 3. Cytoplasmic vacuolation with intercellular spacing.
Many attempts have been made to establish specific immunohistochemical markers for ameloblastomas. For example, it has been suggested that differences in the expression of cell surface carbohydrates with blood group specificity may distinguish ameloblastomas from odontogenic cyst [14], although this hypothesis was not confirmed by other authors. Ki-67 and PCNA (proliferating cell nuclear antigen) are used to check the proliferative index of the UCA and found significantly more PCNA-positive cells in UCA than in DC lining [11]. An immunohistochemical evaluation of Ki-67 in DCs, UCAs, and ameloblastomas arising in DCs confirmed the hypothesis that an ameloblastoma arising from a DC has a similar biological behavior to that of UCA [15]. It has been suggested that calretinin is a specific immunohistochemical markers for neoplastic ameloblastic epithelium and may serve as a diagnostic tool for differentiating cystic odontogenic lesions from ameloblastic tumor [16]. Tsuneki et al. [13] suggested that six immunohistochemical markers K10, K13, K17, perlecan, PCNA and Ulex europaeus agglutinin-I lectin binding (UEA) were useful for distinction of the five cystic jaw lesions [UCA, Keratocystic odontogenic tumor (KCOT), Lateral periodontal cyst (LPC), DC and Radicular cyst (RC)] when their evaluation was combined. UEA is considered to be more specific amongst this six markers to differentiate UCA from KCOT, RC, LPC and DC. Recently, Masloub et al. [17] recommended that high CD10 and osteopontin expression in DC might predict the neoplastic potentiality of the epithelial lining of this cyst. Also, high CD10 and osteopontin expression in UCA might be a useful tool to identify areas with locally invasive behavior and high risk of recurrence. However; up to date, no general recommendations exist. Moreover, currently unaided histologic assessment for UCA remains the gold standard for diagnosis, because of a variable response of UCA to tissue markers. Although, UCAs with islands of ameloblastomatous epithelium may be misdiagnosed as a DC if no more than two histologic sections are examined [18]. Treatment is decided by the clinical behavior and which in turn is dictated by the histological pattern of the ameloblastoma. Based on histologic subgrouping provided by Philipsen and Reichart [6], our cases fall in subgroup 1.3, 1 and 1.2 for case 1, case 2 and case 3 respectively. Our findings are consistent with one study which showed that the mural variety is seen to be more often associated with the ‘non-dentigerous’ type of these lesions, while the intraluminal proliferations are more than twice as frequent in UCAs of the ‘dentigerous’ type [19]. The management of the cystic ameloblastomas remains controversial. We believe that these lesions generally represent a less aggressive type of ameloblastoma and therefore should have a better prognosis. However, they may well be too destructive and infiltrative in their behavior to respond predictably to local enucleation or curettage. The UCAs diagnosed as subgroups 1 and 1.2 can be treated by careful enucleation and the jaw bones salvaged, provided it is salvageable, whereas subgroups 1.2.3 and 1.3 showing intramural growths require radical treatment like resection, as for a solid or multicystic ameloblastoma. Following enucleation, vigorous curettage of the bone should be avoided as it may implant foci of ameloblastoma more deeply into the bone [6]. Chemical cauterization with Carnoy’s solution is also advocated for subgroup 1 and 1.2. The use of Carnoy’s solution to decrease chances of recurrence after conservative surgical treatment of UCAs was initially suggested by Stoelinga and Bronkhorst in 1988 and later many reported the success rate with the same [20]. Late recurrence following treatment is commonly seen, the average interval for recurrence being seven years. The overall recurrence rate of UCAs for all cases was 15%, with some evidence to suggest that the mural histologic subtype has a greater recurrence rate of 35.7% than the others only 6.7% [21]. Recurrence rates are
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also related to the type of initial treatment. Lau et al. [22] reported recurrence rates of 3.6% for resection, 30.5% for enucleation alone, 16% for enucleation followed by Carnoy’s solution application, and 18% by marsupialization followed by enucleation (where the lesion reduced in size). It is often the case that surgeons perform enucleation or excisional biopsy for a presumed dental cyst only to be informed later of the diagnosis of cystic ameloblastoma. The surgeon is then faced with determining whether the patient should undergo more aggressive treatment or to be closely followed with serial radiographs and clinical examinations. However if there is slight suspicion of the lesion being UCA, enucleation followed by treatment with either Carnoy’s solution or liquid nitrogen cryotherapy should be done, so that no further treatment is needed in case of type 1 and 1.2 UCAs. Whenever facilities for frozen section are available an attempt should be made to detect the ameloblastic changes if any so as to modify the surgical margins immediately in an attempt to improve the prognosis. It is pertinent to mention that whole specimen needs to be actively screened for mural invasion in every case of UCA to determine the histological subtype and treatment subsequently. If the histology yields the diagnosis of type 1.2.3 or 1.3, again marginal or partial resection would most aptly reduce the chance of any recurrence. All of our cases were treated by enucleation and prophylactic chemical cauterization, which were therapeutically enough for case 2 and case 3. However, in our case 1 (subtype 1.3), the child was small and resection would cause lots of morbidity, so we preferred follow up than resection. References [1] Yasouka T, Yonemoto K, Kato Y, Tatematsu N. Squamous cell carcinoma arising in dental cyst. J Oral Maxillofac Surg 2000;58:900–5. [2] TajimaY, Sakamoto E, Yammamoto Y. Odontogenic cyst giving rise to an adenomatoid odontogenic tumor-report of a case with peculiar features. J Oral Maxillofac Surg 1992;50:190. [3] Cahn LR. The dentigerous cyst as a potential adamantinoma. Dent Cosmos 1993;75:889.
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