Abstract
Aim
To analyze the relative frequency of different types of odontogenic tumors based on the WHO 2005 histopathological classification of odontogenic tumours and to compare the data with published literature.
Methods
Data collected from seven different hospitals in the same region of the city (south Chennai) were systematically searched for all cases of odontogenic tumors operated on between the years 2005–2010. The histopathology slides of the tumours were reanalyzed for cross verification. The data were also checked for duplication and for recurrence cases. Age, gender and site prevalence were also studied.
Results
Of the 107 cases collected, with full records, 60 (56%) were odontomas. The second most common was ameloblastoma (14%), followed by Keratocystic odontogenic tumour (13%). The rest of the tumours formed 17% of the total.
Conclusions
A comprehensive tumour database should be initiated so that cross referring of cases would be easier and the patients, surgeons and the pathologists would be able to safe guard the information about the tumour for future reference. Many private hospitals lack the facility to store and catalogue histopathological evidences for a prolonged period of time.
Keywords: Keywords, Odontogenic tumour, Prevalence, Ameloblastoma
Introduction
Surgeons, radiologists and pathologists have been improving the classification of tumours and tumour-like lesions of the odontogenic tissues over the years, based on experience, in order to develop an uniform treatment protocol. The classification of these tumours based on origin and histological criteria has been internationally accepted. Odontogenic tumours (OTs) arise from epithelial, ectomesenchymal and/or mesenchymal elements of the tooth-forming tissues. However, the complexity of the OTs and the inability to trace the origin of all the variations seen, present certain uncertainties. This is mainly due to the uncommonness of some lesions, improper preservation of the specimen samples and the paucity of a large series for study and comparison.
In 1971 WHO compiled the ‘histological classification of OTs’ in 1971. It was revised in 1992 and in 2005. The major changes in the new classification system published by WHO in 2005 when compared to the previous versions were the following: (1) parakeratinized odontogenic keratocyst has been termed as keratocystic odontogenic tumour (KCOT) and is regarded as benign tumour derived from odontogenic epithelium; (2) adenoid odontogenic tumour (AOT) has been found to originate from odontogenic epithelium with mature fibrous stroma and not with ectomesenchyme; (3) calcifying odontogenic cyst (COC) has been divided into two benign and one malignant forms; (4) clear cell odontogenic tumour being a malignant lesion and has been termed clear cell odontogenic carcinoma (CCOC); (5) odontogenic carcinosarcoma is has been excluded due to the lack of evidence for its occurrence as a separate entity. A few more changes have been adapted regarding terminology and sub-typings.
Understanding of the most common and the rare OTs will be of great use in their study and clinical management. The assessment of the frequency of occurrence the tumours in different groups of populations holds the key to provisional diagnosis and further planning of the biopsy based on the clinical and radiographic features. It also aids in patient counseling and scheduling the treatment.
In this study we collected the available data from seven different hospitals in the same region of the city (south Chennai) between the years 2005 to 2010. They were tabulated and systematically analysed for assessing the frequency of occurrence based on age, sex, site and type.
Materials and Methods
The pathology departments of 5 different hospitals in South Chennai were contacted by the principal investigators and data of the odontogenic tumours diagnosed by them using full specimen samples were requested. 107 cases were recovered with full records and histopathology slides. The histopathology slides of the tumours were re-analyzed by a group of pathologists for cross verification. The same group of pathologists reviewed all the slides. Parakeratinised keratocyst was renamed as keratocystic odontogenic tumour. The data were also checked for duplication and for recurrence cases using the name and addresses of the patients. When in doubt, the patients were recalled for verification of any recurrence. Radiographic data were also reviewed. Age, gender and site prevalence were tabulated and analysed. Age was sub-grouped as decades.
Results
Table 1 shows the frequency of occurrence of the tumours based on histological typing. Table 2 tabulates the sex predilection, Table 3 depicts site predilection and Table 4 shows age predilection. Table 5 shows the comparison of prevalence rates of OTs in different countries published in International literature. Of the 107 cases analysed, only one case was malignant 99% of the cases were benign. The most common type of tumours excised were odontomas (56%). The second most prevalent were ameloblastomas (14%) followed by KCOT (12.15%). Complex odontomas were slightly more prevalent than the compound odontomas. Solid and unicystic ameloblastomas were equally prevalent. The general male–female ratio was 1:1.6. 71% of the lesions were located in the mandible. Ameloblastomas, KCOT and odontomas were found more frequently in the mandible. The age of the patients varied from 5 to 74 years with a mean age of 31.1 years; 77.57% of cases were of the age between 10 and 39. The peak incidence of these tumours (31.7%) was found in was in the third decade between ages 20–29.
Table 1.
Frequency of occurence of the tumours based on histological typing
| Type of tumor | Number | Percentage |
|---|---|---|
| Odontogenic epithelium with mature fibrous stroma, without odontogenic ectomesenchyme | ||
| Ameloblastomas (AME) | 15 | 14.02 |
| Solid | 8 | |
| Unicystic | 7 | |
| Squamous odontogenic tumor (SOT) | 0 | 0.00 |
| Calcifying epithelial odontogenic tumor (CEOT) | 2 | 1.87 |
| Adenomatoid odontogenic tumor (AOT) | 3 | 2.80 |
| Keratocystic odontogenic tumor (KCOT) | 13 | 12.15 |
| Odontogenic epithelium with odontogenic ectomesenchyme, with or without tissue formation | ||
| Ameloblastic fibroma (AF/AFD) | 1 | 0.93 |
| Ameloblastic fibrodentinoma/fibro-odontoma (AFO) | 1 | 0.93 |
| Odontomas | 60 | 56.07 |
| Complex type (OC) | 38 | |
| Compound type (OCp) | 22 | |
| Odontoameloblastoma (OA) | 0 | 0.00 |
| Calcifying cystic odontogenic tumour (CCOT) | 2 | 1.87 |
| Dentinogenic ghost cell tumour (DGCT) | 0 | 0.00 |
| Mesenchyme and/or odontogenic ectomesenchyme, with or without odontogenic epithelium | ||
| Odontogenic fibroma (OF) | 1 | 0.93 |
| Odontogenic myxoma/myxofibroma (OM) | 2 | 1.87 |
| Benign cementoblastoma (CB) | 1 | 0.93 |
| Malignant odontogenic tumors | 1 | 0.93 |
| Bone related lesions | ||
| Ossifying Fibroma | 1 | 0.93 |
| Fibrous Dysplasia | 2 | 1.87 |
| Osseous Dysplasia | 0 | 0.00 |
| Central giant cell lesion (granuloma) | 1 | 0.93 |
| Cherubism | 0 | 0.00 |
| Aneurysmal bone cyst | 0 | 0.00 |
| Simple bone cyst | 1 | 0.93 |
| Total | 107 | |
Table 2.
Sex predilection of the tumours
| Type of tumor | Male | Female | Ratio |
|---|---|---|---|
| Odontogenic epithelium with mature fibrous stroma, without odontogenic ectomesenchyme | |||
| Ameloblastomas (AME) | 9 | 6 | 1.5:1.0 |
| Solid | 4 | 4 | 1.0:1.0 |
| Unicystic | 5 | 2 | 2.5:1.0 |
| Squamous odontogenic tumor (SOT) | 0 | 0 | |
| Calcifying epithelial odontogenic tumor (CEOT) | 1 | 1 | 1.0:1.0 |
| Adenomatoid odontogenic tumor (AOT) | 1 | 2 | 1.0:2.0 |
| Keratocystic odontogenic tumor (KCOT) | 8 | 5 | 1.6:1.0 |
| Odontogenic epithelium with odontogenic ectomesenchyme, with or without tissue formation | |||
| Ameloblastic fibroma (AF/AFD) | 0 | 1 | |
| Ameloblastic fibrodentinoma/fibro-odontoma (AFO) | 0 | 1 | |
| Odontomas | 28 | 32 | 1.0:1.1 |
| Complex type (OC) | 20 | 18 | 1.1:1.0 |
| Compound type (OCp) | 8 | 14 | 1.8:1.0 |
| Odontoameloblastoma (OA) | 0 | 0 | |
| Calcifying cystic odontogenic tumour (CCOT) | 1 | 1 | 1.0:1.0 |
| Dentinogenic ghost cell tumour (DGCT) | 0 | 0 | |
| Mesenchyme and/or odontogenic ectomesenchyme, with or without odontogenic epithelium | |||
| Odontogenic fibroma (OF) | 1 | 0 | 1.0:1.0 |
| Odontogenic myxoma/myxofibroma (OM) | 1 | 1 | 1.0:1.0 |
| Benign cementoblastoma (CB) | 0 | 1 | |
| Malignant odontogenic tumors | 1 | 0 | |
| Bone related lesions | |||
| Ossifying Fibroma | 1 | 0 | |
| Fibrous Dysplasia | 1 | 1 | 1.0:1.0 |
| Osseous Dysplasia | 0 | 0 | |
| Central giant cell lesion (granuloma) | 0 | 1 | |
| Cherubism | 0 | 0 | |
| Aneurysmal bone cyst | 0 | 0 | |
| Simple bone cyst | 0 | 1 | |
| Total | 52 | 86 | 1.0:1.6 |
Table 3.
Site predilection
| Type of tumor | Maxilla | Mandible | Ratio |
|---|---|---|---|
| Odontogenic epithelium with mature fibrous stroma, without odontogenic ectomesenchyme | |||
| Ameloblastomas (AME) | 2 | 13 | 1.0: 6.5 |
| Solid | 4 | 4 | 1.0:1.0 |
| Unicystic | 3 | 4 | |
| Squamous odontogenic tumor (SOT) | 0 | 0 | |
| Calcifying epithelial odontogenic tumor (CEOT) | 1 | 1 | 1.0:1.0 |
| Adenomatoid odontogenic tumor (AOT) | 1 | 2 | 1.0:2.0 |
| Keratocystic odontogenic tumor (KCOT) | 3 | 10 | 1.0: 3.3 |
| Odontogenic epithelium with odontogenic ectomesenchyme, with or without tissue formation | |||
| Ameloblastic fibroma (AF/AFD) | 0 | 1 | |
| Ameloblastic fibrodentinoma/fibro-odontoma (AFO) | 0 | 1 | |
| Odontomas | 18 | 42 | 1.0:2.3 |
| Complex type (OC) | 13 | 25 | 1.0:1.9 |
| Compound type (OCp) | 5 | 17 | 1.0:3.4 |
| Odontoameloblastoma (OA) | 0 | 0 | |
| Calcifying cystic odontogenic tumour (CCOT) | 1 | 1 | 1.0:1.0 |
| Dentinogenic ghost cell tumour (DGCT) | 0 | 0 | |
| Mesenchyme and/or odontogenic ectomesenchyme, with or without odontogenic epithelium | |||
| Odontogenic fibroma (OF) | 0 | 1 | |
| Odontogenic myxoma/myxofibroma (OM) | 1 | 1 | 1.0:1.0 |
| Benign cementoblastoma (CB) | 1 | 0 | |
| Malignant odontogenic tumors | 1 | 0 | |
| Bone related lesions | |||
| Ossifying Fibroma | 0 | 1 | |
| Fibrous Dysplasia | 2 | 0 | |
| Osseous Dysplasia | 0 | 0 | |
| Central giant cell lesion (granuloma) | 0 | 1 | |
| Cherubism | 0 | 0 | |
| Aneurysmal bone cyst | 0 | 0 | |
| Simple bone cyst | 0 | 1 | |
| Total | 31 | 76 | 1.0:2.45 |
Table 4.
Age predilection
| Type | Age range | Mean age | 0–9 | 10–19 | 20–29 | 30–39 | 40–49 | 50–59 | 60+ |
|---|---|---|---|---|---|---|---|---|---|
| AME | 6 to 62 | 24.8 | 2 (6, 9) | 4 (16, 17, 17, 18) | 5 (22, 22, 24, 24, 27) | 2 (32, 35) | 1 (41) | 1 (62) | |
| CEOT | 53, 58 | 55.5 | 2 (53, 58) | ||||||
| AOT | 18, 22, 32 | 24 | 1 (18) | 1 (22) | 1 (32) | ||||
| KCOT | 5 to 54 | 27.6 | 1 (5) | 2 (15, 19) | 4 (20,21, 23, 28) | 4 (30, 31, 33, 37) | 1 (43) | 1 (54) | |
| AF/AFD | 25 | 25 | 1 (25) | ||||||
| AFO | 20 | 20 | 1 (20) | ||||||
| Odontomas | 12 to 40 | 28.2 | 0 | 18 | 19 | 11 | 4 | 8 | |
| CCOT | 35, 40 | 37.5 | 1 (35) | 1 (40) | |||||
| OF | 38 | 38 | 1 (38) | ||||||
| OM | 24,33 | 28.5 | 1 (24) | 1 (33) | |||||
| CB | 20 | 20 | 1 (20) | ||||||
| Malignant | 74 | 74 | 1 (74) | ||||||
| OF | 34 | 34 | 1 (34) | ||||||
| FD | 17 | 17 | 1 (17) | 1 (31) | |||||
| CGCG | 37 | 37 | 1 (37) | ||||||
| BC | 7 | 7 | 1 (7) | ||||||
| TOTAL | 5 to 74 | 31.13 | 3.7% | 24.29% | 31.77% | 21.49% | 6.54% | 10.28% | 1.87% |
Table 5.
Comparison of prevalence studies around the world
| Tumour | Our series | Zhu (japan) 1993 [1] | Daley et al. (Canada) 1994 [2] | Odukoya (nigeria) 1995 [3] | Mosqueda-Taylor et al. (Mexico) 1997 [4] | Arotiba (nigeria) 1997 [5] | Lu et al. (china) 1998 [6] | Ochsenius et el (Chile) 2001 [7] | Tamme (Estonia) 2001 [8] | Santos et al. (Brazil) 2001 [9] | Simon et al. (Tanzania) 2005 [10] | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Total | 102 | % | 828 | 444 | 289 | 349 | 128 | 759 | 362 | 75 | 127 | 116 |
| AME % | 15 | 14.71 | 58.6 | 15 | 59 | 24.6 | 59 | 59 | 20 | 25.3 | 31 | 80 |
| SOT % | 0 | 0.00 | 0 | 0 | 1 | 0 | 0 | 0.4 | 0.6 | 0 | 0 | |
| CEOT % | 2 | 1.96 | 0.9 | 1.4 | 0.4 | 0.9 | 1.6 | 0.9 | 0.6 | 1.3 | 0 | 1.7 |
| AOT % | 3 | 2.94 | 1.8 | 3.7 | 6.2 | 7.4 | 13 | 8.3 | 6.6 | 1.3 | 8.7 | 0.9 |
| KCOT % | 13 | 12.75 | ||||||||||
| AF/AFD % | 1 | 0.98 | 0.6 | 1.7 | 4.5 | 1.5 | 3.1 | 1.8 | 0.6 | 16 | 1.6 | 1.7 |
| AFO % | 1 | 0.98 | 0.2 | 3.4 | 0 | 0.9 | 0.8 | 0.3 | 2.2 | 0 | 0.8 | 0 |
| Odont% | 60 | 58.82 | 28.4 | 57 | 4.2 | 35.8 | 0 | 6.7 | 45 | 34.7 | 50 | 2.6 |
| OA % | 0 | 0.00 | 0.4 | 0 | 0 | 0 | 0.3 | 0 | 0 | 0 | 0 | |
| CCOT % | 2 | 1.96 | 2.8 | 0 | 2.4 | 0 | 1.6 | 0.9 | 0.6 | 1.3 | 0 | 1.7 |
| OF % | 1 | 0.98 | 1.3 | 5.3 | 4.5 | 1.5 | 1.6 | 0.7 | 5.5 | 0 | 0 | 1.7 |
| OM % | 2 | 1.96 | 5.6 | 5.6 | 12 | 18.3 | 16 | 8.4 | 8.8 | 12 | 4.7 | 7 |
| CB % | 1 | 0.98 | 0.2 | 2 | 0.7 | 9 | 0 | 26 | 1.7 | 8 | 2.4 | 1.7 |
| Malignant % | 1 | 0.98 | 0.1 | 0.3 | 5.2 | 1.2 | 2.3 | 6 | 0.6 | 1.3 | 0 | 0 |
| Tumour | Our series | Adebayo et al. (Nigeria) 2005 [11] | Ladeinde et at (Nigeria) 2005 [12] | Fernandes et al. (Brazil) 2005 [13] | Buchner et al. (USA) 2006 [14] | Olgac et al. (Turey) 2006 [15] | Jing et al. (china) 2007 [16] | Okada et al. (Srilanka) 2007 [17] | Sriram et al. (India) 2008 [18] | Gupta B et al. (India) 2010 [19] | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Total | 102 | % | 318 | 319 | 340 | 1088 | 527 | 1054 | 226 | 250 | 489 |
| AME % | 15 | 14.71 | 73.3 | 63 | 45.3 | 11.7 | 25.2 | 62.7 | 69.8 | 62 | 67.7 |
| SOT % | 0 | 0.00 | 0.3 | 2 | 1.5 | 0.3 | 2.1 | 0.3 | 0.9 | ||
| CEOT % | 2 | 1.96 | 1 | 1.6 | 1.2 | 0.5 | 0.9 | 0.9 | 1.3 | 5.52 | |
| AOT % | 3 | 2.94 | 2.8 | 7.5 | 3.8 | 1.7 | 2.1 | 6.5 | 9.3 | 12 | 9 |
| KCOT % | 13 | 12.75 | |||||||||
| AF/AFD % | 1 | 0.98 | 3.1 | 2 | 1.8 | 1.6 | 1.5 | 1.8 | 0.4 | ||
| AFO % | 1 | 0.98 | 0.3 | 0 | 0.3 | 1.7 | 0 | 0.4 | 1.3 | ||
| Odont% | 60 | 58.82 | 2.2 | 2.5 | 25 | 75.6 | 20.7 | 7.4 | 4.4 | 6 | 7.77 |
| OA % | 0 | 0.00 | 0 | 0.3 | 1.8 | 0 | 0 | 0.2 | 0 | ||
| CCOT % | 2 | 1.96 | 2.5 | 5.3 | 3.5 | 0.1 | 5.5 | 4.7 | 4.4 | ||
| OF % | 1 | 0.98 | 1.2 | 5.3 | 3.2 | 1.5 | 9.9 | 0.5 | 0.4 | ||
| OM % | 2 | 1.96 | 11.9 | 6.5 | 9.1 | 22 | 15.7 | 7.2 | 4.9 | 6 | |
| CB % | 1 | 0.98 | 0 | 0.6 | 2.3 | 0.9 | 1.9 | 3.1 | 1 | ||
| Malignant % | 1 | 0.98 | 1.3 | 3.4 | 0.3 | 0.4 | 1.1 | 4.7 | 0 | 3.07 | |
We did not encounter any cases of Squamous odontogenic tumor (SOT), Odontoameloblastoma (OA), Dentinogenic ghost cell tumour (DGCT), Osseous Dysplasia, Cherubism or Aneurysmal bone cyst (ABC). We also recovered only one case each of Simple bone cyst, Central giant cell lesion (granuloma), Ossifying Fibroma, Benign cementoblastoma (CB), Odontogenic fibroma (OF), Ameloblastic fibrodentinoma (AFO) and Ameloblastic fibroma (AF/AFD).
Most of the hospitals did not preserve the histological data of the specimen and lacked a tumour registry. Due to improper communication and a lack of a centralized database, recurrent cases could not be tracked with ease. There was no significant difference in the treatment protocol followed by the different surgeons, except in the treatment of cystic tumours. Most surgeons prefer a radical approach with resection as the most common treatment preformed. The relatively large sizes of the tumours indicate late presentation of the cases especially in teaching institutions. However, these data could only be presented as an observation since complete data could not be recovered for all cases in order to derive a calculated conclusion.
Discussion
There still exists a lack of uniform nomenclature among surgeons and pathologists, the WHO classification has not entirely been adapted completely. There are few published reports of large series of OTs around the world. Table 5 shows comparative data on the relative prevalence of OTs in the present study and other reported series.
Studies from Japan, Nigeria, China, Tanzania and Srilanka show a higher prevalence of ameloblastoma than odontomas. [1, 3, 5, 6, 10–13, 16, 17] Our study results were comparable with those of Canada, Mexico, USA, Chile, Europe and India. [2, 4, 7–9, 14, 15, 18, 19]. The percentage of odontomas was lower in the other studies from India that were based in government hospitals [18, 19] when compared to ours. While one of the Nigerian study has not taken odontomas into account, Jing et al. [16] comment that these discrepancies in the number of odontomas being lesser in their populations on comparison with the others is probably a result from geographic variation, but it should be mentioned that the incidence of odontoma in some countries was likely underestimated due to the unique clinical features of this tumour and insufficient hospital management. Most of these tumours exhibit self-limited growth and do not cause clinical symptoms. Many patients do not think it necessary to see a doctor. Treatment in many cases was carried out in the dental office and the cases were not registered or sent for histopathological confirmation. However, majority of our data was from teaching institutions and private hospitals equipped with orthopantomograms and therefore aberrant radiological findings were confirmed and the patients counseled about the OTs and hence the odontomas are not ignored.
SOT and OA are relatively rate in almost all studies. We were not able to find a single case of the same too. DGCT seems to have been mixed with the COC. The previous WHO classification implied that all these lesions were neoplastic in nature and used COC as a general term. In 2005 COCs were divided into three types: calcifying cystic odontogenic tumour (CCOT), a benign cystic neoplasm with ameloblastoma-like epithelium with ghost cells that may calcify; dentinogenic ghost cell tumour (DGCT) with ameloblastoma-like epithelium in a mature connective tissue stroma and ghost cells in association with dysplastic dentin; and ghost cell odontogenic carcinoma (GCOC) which is the malignant variant of CCOT or DGCT. In the previous classification CCOT was the abbreviation for clear cell odontogenic tumour which is now termed clear cell odontogenic carcinoma with the abbreviation of CCOC. It is hard to evaluate these information with findings from previous reports because different histologic criteria were used by different authors when classifying these lesions. Likewise the slides available to us also could not be clearly demarcated.
Likewise since most of the studies compared did not follow the 2005 classification, the prevalence of KCOT could not be compared.
The prevalence rate of AOT is comparable with that of the rest of the world with the exception of one study from Nigeria [5], which shows a slightly higher prevalence at 12.5%. However other studies from Nigeria are comparable. While we had a prevalence rate of 2.9%, that of the rest of the world ranged from 0.9 to 12.5%. Studies from Srilanka [12] and Brazil [9] and China [6] ranged from 8.3 to 9.3%.
These studies however did not study the lesions from the bone related lesions namely Simple bone cyst, Aneurysmal bone Cyst, Cherubism, Central giant cell lesion (granuloma), Osseous Dysplasia, Fibrous Dysplasia and Ossifying Fibroma. Even though we had only five cases of the same, the prevalence of these lesions has been significant.
Conclusion
Retrospective analyses of the relative frequency of OTs in different countries will be of help in edifying the understanding of OTs, which is important for both oral maxillofacial surgeons and pathologists. Preservation of data available and the centralization of a tumor registry would benefit India very much. Much of the data that we collected could not be used for this study due to incomplete case sheets and improper preservation and cataloguing. Though the number of cases available to us was low, the prevalence rate threw light on the most common lesions in our area of consultation.
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