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Relative frequency of odontogenic tumors in Sri Lanka: Analysis of 1677 cases
Pathology – Research and Practice 208 (2012) 225–230
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Original article
Relative frequency of odontogenic tumors in Sri Lanka: Analysis of 1677 cases B.S.M.S. Siriwardena, T.M.P.B. Tennakoon, W.M. Tilakaratne ∗ Department of Oral Pathology, Faculty of Dental Sciences, University of Peradeniya,Sri Lanka
a r t i c l e
i n f o
Article history: Received 30 January 2012 Received in revised form 9 February 2012 Accepted 9 February 2012 Keywords: Odontogenic tumors WHO classification Ameloblastoma KCOT Frequency
a b s t r a c t Odontogenic tumors (OTs) constitute a heterogeneous group of lesions with diverse histopathological features and clinical manifestations. The present study is to determine the frequency of odontogenic tumors (OTs) in Sri Lankan population. A total of 1677 cases of OTs were retrieved and analyzed for age, gender and primary site of the tumors. Cases were re-classified according to the 2005 WHO classification of OTs. The relative frequency of different types of tumors was also analyzed and compared with the literature. OTs represent 3.75% of all cases received during a period of 30 years. Ninety-eight percent of these tumors were benign and the rest malignant. Mandible to maxilla ratio is 2.8:1. The posterior part, the molar region, is the most frequently affected site for the mandible whilst it is the anterior region for the maxilla. The age ranges from 1 to 80 years, with a mean age of 30.6 years. Ameloblastoma of solid/multicystic and unicystic types showed a high preponderance for the mandible (>90%) with a ratio of 12.9:1 and 10.8:1, respectively. Out of 1677 cases, 48.7% were ameloblastoma, and other tumors, such as keratocystic odontogenic tumor (KCOT) and odontoma, were 25.7% and 10.1%, respectively. There is a significant change in the frequency of OTs after the inclusion of odontogenic keratocyst as a tumor. Although odontoma is said to be the commonest in western countries, our results showed ameloblastoma as the commonest followed by KCOT, and the relative frequencies of different tumors have changed significantly as a result of inclusion of KCOT in the new classification. © 2012 Elsevier GmbH. All rights reserved.
Introduction Odontogenic tumors (OT) are lesions derived from epithelial, ectomesenchymal and/or mesenchymal elements of the toothforming apparatus. It constitutes a heterogeneous group of lesions with diverse histopathological features and clinical manifestations, and the spectrum of the biological behavior of these lesions ranges from hamartomatous or non-neoplastic tissue proliferations to malignant neoplasms. The majority of studies [8,12,17] from various parts of the world were based on the 1971 [20] and 1992 [10] WHO histological classification, and few on the recently published updated edition of WHO [3] classification. Several retrospective studies carried out in Asia, Africa, Europe and America reveal that differences exist in the relative frequency of various histological types [7,9,13,16,19,22]. Therefore, the purpose of this study was to determine the relative frequency of odontogenic tumors with regard to the new WHO classification and to compare these data with previously published reports after the 2005 OT classification from other parts of the world. Further, we intended to analyze the changing pattern of
frequency with the inclusion of keratocystic odontogenic tumor (KCOT) in the new classification. Materials and methods The surgical histopathology records of the Department of Oral Pathology, Faculty of Dental Sciences, University of Peradeniya were reviewed retrospectively from January 1980 to August 2011. A total of 1677 cases of OTs were collected and reviewed. Recurrent tumors were considered as a single case. Two investigators (WMT, SS) evaluated the hematoxylin and eosin-stained sections, and the diagnosis in each case was either re-confirmed or modified in accordance with the third edition of the WHO classification. The frequency and distribution regarding age, sex and primary site of the lesion were analyzed and compared with the studies which were published before and after 2005 WHO classification in the English literature. Each jaw was divided into three anatomical parts as anterior, premolar and molar in order to decide the location of the tumor. Results
∗ Corresponding author. Tel.: +94 812397435; fax: +94 81 2388948. E-mail address: [email protected] (W.M. Tilakaratne). 0344-0338/$ – see front matter © 2012 Elsevier GmbH. All rights reserved. doi:10.1016/j.prp.2012.02.008
During the period of 30 years, a total of 44,458 biopsies were received, and 3.8% of them were OTs. Of a total of 1677 cases
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B.S.M.S. Siriwardena et al. / Pathology – Research and Practice 208 (2012) 225–230
Table 1 Frequency and gender distribution of odontogenic tumors. Abbreviation Benign Solid/multicystic ameloblastoma Peripheral ameloblastoma Desmoplastic ameloblastoma Unicystic ameloblastoma Squamous odontogenic tumor Calcifying epithelial odontogenic tumor Adenomatoid odontogenic tumor Keratocystic odontogenic tumor Ameloblastic fibroma Ameloblastic fibro-odontoma Odontoma Calcifying cystic odontogenic tumor Dentinogenic ghost cell tumor Odontogenic fibroma Odontogenic myxoma Odontogenic myxo fibroma Cementoblastoma Malignant Malignant ameloblastoma Clear cell odontogenic carcinoma PIOSCC arising from OKC PIOSCC arising from odontogenic cysts Ameloblastic carcinoma Ameloblastic fibrosarcoma Primary intraosseous carcinoma
Total cases
S/MA PA DA UA SOT CEOT AOT KCOT AF AFO ODT CCOT DGCT OF OMYX OMF CMB MA CCOC PIOSCC ex OKC PIOSCC ex OC AC AFS PIOC
Female
%
Male
%
Male:Female
520 6 29 261 7 25 78 431 15 9 169 24 5 7 64 3 1
259 4 15 124 6 15 52 192 5 5 82 7 2 4 32 3 1
49.8 66.7 51.7 47.5 85.7 60.0 66.7 44.5 33.3 55.6 48.5 29.1 40.0 57.1 50.0 100.0 100.0
261 2 14 137 1 10 26 239 10 4 87 17 3 3 32 0 0
50.2 33.3 48.3 52.5 14.3 40.0 33.3 55.5 66.7 44.4 51.5 70.8 60.0 42.9 50.0 0.0 0.0
1:1 1:2 1:1.1 1.1:1 1:6 1:1.5 1:2 1.2:1 2:1 1:1.3 1.1:1 2.4:1 1.5:1 1:1.3 1:1 NA NA
1 5 2 1 3 1 10
1 3 0 0 2 0 5
100.0 60.0 0.0 0.0 66.7 0.0 50.0
0 2 2 1 1 1 5
0.0 40.0 100.0 100 33.3 100.0 50.0
NA 1:1.5 NA NA 1:2 NA 1:1
PIOSCC – primary intra-osseous squamous cell carcinoma, NA – not applicable.
of OTs, 1654 (98.6%) were benign and 23 (1.4%) were malignant. Ameloblastoma was the most common tumor (48.7%), and the solid/multicystic (S/MA) variant was the commonest type (31%) followed by KCOT (25.7%) and odontoma (10%). Table 1 shows the frequency and gender distribution of OTs. Out of all S/MA, 31.9% and 34.2% were plexiform and follicular ameloblastoma, respectively. There were 858 males and 819 females. Although there is no gender predilection (1:1) for most OTs, there is a female preponderance for squamous odontogenic tumor (SOT). The age of the patients ranges from 1 year to 86 years, with a mean age of 30.6
years. The majority of cases were distributed between age 10 and 49 with a peak incidence in the second and third decades (Table 2). As described in the literature, the mean age for odontoma, adenomatoid odontogenic tumors (AOT) and unicystic ameloblastoma (UA) was 19, 18 and 29.9 years, respectively. Desmoplastic ameloblastoma (DA) and peripheral ameloblastoma (PA) tend to occur in older individuals. Most malignant OTs also predominantly occurred in older patients (Table 2). There were 5 cases of Dentinogenic ghost cell tumor (DGCT), which is a new entity according to the 2005 WHO classification. The affected age groups were 10–19 (2 cases)
Table 2 Distribution of odontogenic tumors in different age groups. Age group (years)
Solid/multicystic ameloblastoma Peripheral ameloblastoma Desmoplastic ameloblastoma Unicystic ameloblastoma Squamous odontogenic tumor Calcifying epithelial odontogenic tumor Adenomatoid odontogenic tumor Keratocystic odontogenic tumor Ameloblastic fibroma Ameloblastic fibro-odontoma Odontoma Calcifying cystic odontogenic tumor Dentinogenic ghost cell tumor Odontogenic fibroma Odontogenic myxoma Odontogenic myxo fibroma Cementoblastoma Malignant ameloblastoma Clear cell odontogenic carcinoma Carcinoma arising from OKC PIOSCC arising from odontogenic cysts Ameloblastic carcinoma Ameloblastic fibrosarcoma Primary intraosseous carcinoma Total
0–9
10–19
20–29
30–39
40–49
50–59
60–69
70–79
80–89
NS
Total
Mean
6 – – 7 – – 2 8 2 7 16 2 – 1 5 – – – 1 – – – – – 57
82 – – 68 1 5 53 78 3 1 94 4 2 2 15 2 – – – – – – – – 410
139 – 3 66 – 8 14 124 3 – 31 2 – – 24 – 1 – – – – 1 1 – 417
98 1 3 49 2 2 4 87 1 – 8 2 – 1 9 – – – – – – – – – 267
75 3 9 36 – 3 3 55 1 – 5 3 – – 2 1 – 1 1 1 – – – 4 203
57 1 6 12 3 5 – 41 – – 5 4 – 3 4 – – – 2 1 1 – – 1 146
34 – 6 13 1 – – 20 4 – 3 4 1 – 1 – – – – – – 2 – 5 94
10 – – 4 – – – 6 – – 1 3 2 – 3 – – – 1 – – – – – 30
4 – 1 2 – – – 1 – – – – – – – – – – – – – – – – 8
15 1 1 4 – 2 2 11 1 1 6 – – – 1 – – – – – – – – – 45
520 6 29 261 7 25 78 431 15 9 169 24 5 7 64 3 1 1 5 2 – 3 1 10 1677
34.2 39.0 47.1 29.9 45.3 30.4 18.0 31.3 29.4 6.0 19.0 43.0 46.0 33.0 27.0 25.0 29.0 43.0 44.8 55.5 57.0 48.7 22.0 55.8 30.8
PIOSCC – primary intra-osseous squamous cell carcinoma.
B.S.M.S. Siriwardena et al. / Pathology – Research and Practice 208 (2012) 225–230
Frequency of common OT before and aer 2005 WHO classificaon
50
44
45 40
35.8
2005 WHO classificaon
35 30
1992 WHO classificaon
24.1
25 20
14
15 10
3.7
5
6
8.9 5.3
0 Ameloblastoma
Odontoma
AOT
O Myxoma O.Myxoma
Fig. 1. Changing pattern of OTs after inclusion of KCOT into 2005 WHO classification.
years and 60–79 (3 cases) years. The tumor shows mandibular predilection. The mandible was the mostly affected site of occurrence for most OTs, and for overall it is 62.7% with a ratio of 2.8:1 (Table 3). Ameloblastoma of solid/multicystic and unicystic types showed a higher preponderance for the mandible (>90%) with a ratio of 12.9:1 and 10.8:1, respectively. In accordance with the literature, AOT and odontoma show a higher maxillary predilection with a ratio of 2.3:1 and 6.6:1, respectively. Desmoplastic ameloblastoma tend to occur commonly in anterior maxilla. Generally, except odontoma and AOT, the OTs were more commonly encountered in the posterior part of the jaws. The majority of OTs occurred in the posterior part of the mandible, including the premolar and molar region in contrast to maxilla, where anterior maxilla was affected more frequently. There is a slight predominance for the right side of both jaws. Tumors that involved more than two zones and some extending to the opposite side were mainly ameloblastoma (S/MA & UA) and KCOT. The cases that involved more than one zone in mandible were 45.5%, and in maxilla it was 31.2%. The relative frequency of OTs found in the present study was compared with studies reported in the literature which followed the new WHO 2005. OT classification is given in Table 4. There were only 7 studies [2,6,9,13,19,23,24] available in the English literature, and according to these, ameloblastoma is the commonest odontogenic tumor except two studies which revealed odontoma and KCOT as the commonest. The second most common tumor is KCOT followed by odontoma. It is interesting to note that the frequency of ameloblastoma in comparison to other OTs has reduced significantly, as a result of the inclusion of OKC as a benign tumor in the 2005 WHO classification (Fig. 1). There were 22 cases of malignant OTs comprising mostly primary intraosseous carcinomas (10 cases) and clear cell odontogenic carcinoma (5 cases). A single case of metastasizing ameloblastoma (malignant ameloblastoma) is also reported in this study. Discussion Odontogenic tumors develop from the tissues of tooth formation and constitute a diverse group of lesions. The classification of OTs in the revised 2nd edition of WHO (1992) was widely used in previous studies, and there were only a few studies available [2,6,9,13,19,23,24] in accordance with the updated edition in 2005. The first classification of this heterogeneous group of lesions was published in 1971 [20], and an updated second edition of the WHO classification was published in 1992 [10]. Due to advances in immunohistochemistry and molecular biology during the last decade, a revision of the 1992 edition of the WHO classification was proposed by Philipsen and Reichart and published in 2005 [3].
227
The present study analyzed the largest series of OTs, comprising 1677 cases reported in the literature despite the fact that the series is from a single institute. Jing et al., in 2007, analyzed 1642 cases of OTs over a period over 53 years [13]. All the cases presented in our series (30-year period) were re-evaluated and re-classified according to the 2005 WHO classification. In the present study, ameloblastoma was the commonest OT followed by KCOT and odontoma. These results were consistent with the data from Brazil [19], China [9,13] and Africa [23]. Odontoma was the commonest OT reported in the Western world [6]. It can be hypothesized that the discrepancy may be due to geographic variation. It is reported that in some countries, odontomas are underestimated due to poor patient compliance, absence of clinical symptoms and self limited growth in some tumors. Therefore, many cases are managed by peripheral units and may be inadequately documented or may not be sent for histopathological investigations. Age/gender distribution Although there is no significant gender predilection for OTs in this present study, there is a female preponderance reported in Chile, Mexico and Nigeria [1,15,21]. A marked female predilection was observed in SOT, which was 6:1. Similarly, PA, AOT and CEOT showed a slight female preponderance. In contrast, calcifying cystic odontogenic tumor (CCOT), DGCT and ameloblastic fibroma occurred predominantly in males. The mean age was 30.6 years, and the majority of the cases occurred between age 10 and 49 with a peak incidence in the 3rd decade of life. S/MA, KCOT showed a marked prevalence in this age range. As accepted globally, several OTs, such as odontoma, AOTs and UAs, were more pronounced in the 2nd decade of life. Primary site In agreement with the literature, OTs are present mostly in the mandible, especially in the posterior zone (molar region), and a significantly higher number of OTs, mostly ameloblastoma, involve more than one zone. The mean age of ameloblastoma in the present study was 34.2 years, which falls within the range of previously published studies [1,9,11,16]. More than 90% of S/MA and UA occurred in the mandible, especially in the posterior region, and the finding was comparable with the published studies [11,16]. Frequency As odontogenic keratocyst was renamed as KCOT in the current WHO classification, the frequency of OTs has been changed. In the studies done so far with the new classification, including the present study, KCOT is the 2nd most common OT, and it amounts to 25.7% in the present series. Other studies also showed the frequency of KCOT ranging from 19.5% to 52% [9,13,19,23]. The available reports have not sub-classified ameloblastoma as SM/A, UA, DA according to the new classification, making it difficult to comment on the frequency of subtypes globally. According to this study, out of the 4 types, 63.7% of them were S/MA and 31.9% were UA. In the present series, 3.8% of the cases were odontogenic myxomas. Ameloblastic fibroma and ameloblastic fibro odontoma together account for 1.4%. New additions/changes in the 2005 WHO classification of OTs Except KCOT, which is the major influence on changing the frequency of OTs, there are other tumors that have changed their name or the position in the 2005 WHO classification of OTs. Adenomatoid
228
Table 3 Site distribution of odontogenic tumors. Mandible Anta
a b c d e f g h i
Anterior. Posterior. Total. Left. Right. Mandible. Maxilla. Not specified. Not applicable.
Tc
Ld
Re
L
R
L
R
L
R
mdf
2 1 – 1 – – 1 9 – – 3 0 1 – – – – – – – – – – – 18
7 – – 4 – 1 2 10 – – 1 2 1 – – – – – – – 1 – – – 28
34 – 1 15 – – 2 18 – – 6 2 – 2 2 – – – 2 – – – – – 84
29 – – 18 – 1 4 34 – 2 8 4 2 – 4 – – – 1 – – – – – 107
43 – – 36 – 1 – 72 1 2 10 1 – – 4 – – – – – – 1 – – 171
44 1 1 36 – 1 1 60 2 – 12 – – – 3 – – 1 – 1 – – – 3 166
71 – – 28 1 – – 19 1 – 3 2 – 1 2 2 – – 1 – – – – 1 132
68 – 5 56 – 5 1 29 – – 1 3 – – 3 – – – – – – – – 1 172
77 1 6 33 1 5 5 34 3 – 2 2 1 – 3 – – – – – – – – 1 174
375 3 13 227 2 14 16 285 7 4 46 16 5 3 21 2 – 1 4 1 1 1 – 6 1053
%
92.8 60.0 46.4 91.5 50.0 73.7 30.8 74.4 53.8 50.0 30.3 70.4 100 50.0 44.7 100. – 100 80.0 50.0 100 33.3 – 73.9
Man:Max
Ant
Middle
Post
T
L
R
L
R
L
R
L
R
mxg
2 – 1 1 – – 5 5 – – 23 1 – – 1 – – – – – – – – – 39
1 1 3 1 – – 14 20 – 2 44 1 – – 1 – – – – – – – – – 88
2 – 1 3 – – 5 9 2 1 10 1 – 2 4 – – – – – – – 1 – 41
4 – 2 5 1 3 4 9 2 1 6 – – – 1 – – – – – – – – – 38
2 – – – – – – 10 1 – 5 – – – 3 – – – – – – – – – 21
3 – – 1 – – – 13 – – 3 1 – – 3 – – – – – – – – – 24
3 – 5 3 – 1 5 9 – – 1 1 – – 7 – 1 – 1 – – 2 – 4 43
10 – 1 3 – 1 3 15 1 – 5 2 – – 5 – – – – – – – – – 46
2 1 2 4 1 – 8 – – 9 1 – 1 1 – – – – 1 – – – – 31
% NSh
29 2 15 21 2 5 36 98 6 4 106 8 – 3 26 – 1 – 1 1 – 2 1 4 371
7.2 40.0 53.6 8.5 50.0 26.3 69.2 25.6 46.2 50.0 69.7 29.6 – 50.0 55.3 – 100 – 20.0 50.0 – 66.7 100 26.1
116 1 1 13 3 6 26 48 2 1 17 – – 1 17 1 – – – – – – – – 253
12.9:1 1.5:1 1:1.2 10.8:1 1:1 2.8:1 1:2.3 2.9:1 1.2:1 1:1 1:6.6 3:1 NA 1:1 1:1.2 NAi NA NA 4:1 1:1 NA 1:2 NA 1.5:1 2.8:1
B.S.M.S. Siriwardena et al. / Pathology – Research and Practice 208 (2012) 225–230
S/MA PA DA UA SOT CEOT AOT KCOT AF AFO ODT CCOT DGCT OF OMYX OMF CMB MA CCOC PIOSCC ex OKC PIOSCC ex OC AC AFS PIOC Total
Maxilla Postb
Middle
Table 4 Comparison of the present study with the studies published after 2005 WHO classification. %
520 6 29 261 7 25 78 431 15 9 169 24 5 7 64 3 1 1 5 2 1 3 1 10 – 1677
31.0 0.4 1.7 15.6 0.4 1.5 4.7 25.7 0.9 0.5 10.1 1.4 0.2 0.4 3.8 0.2 0.06 0.06 0.3 0.1 0.06 0.2 0.06 0.6 – 100.04
Hai-Yan et al.
%
Jing et al.
%
Avelar et al.
%
GaitanCepeda et al.
%
Tawfik et al.
%
Osterne et al.
%
Gill et al.
316 6 7 149 – 6 27 507 13 12 80 26
24.1 0.5 0.5 11.4 – 0.5 2.1 38.7 1.0 0.9 6.1 2.0
661 – – – 3 10 68 588 19 4 78 36
40.3 – – – 0.2 0.6 4.1 35.8 1.2 0.2 4.7 2.2
57 – – – 1 5 13 69 4 1 54 15
23.7 – – – 0.4 2.0 5.4 30.0 1.7 0.4 22.1 6.3
25 – – – – 2 2 53 – – 42 –
18.7 – – – – 1.5 1.5 39.6 – – 31.3 –
34 – – – – 3 3 16 2 – 11 –
41.5 – – – – 3.7 3.7 19.5 2.4 – 13.4 –
54 – – – – 1 1 52 4 – 36 7
29.2 – – – – 0.5 0.5 28.1 2.2 – 19.5 3.8
21 34 – 22 – 8 – – – 1 49 25 1309
1.6 2.6 – 1.7 – 0.6 – – – 0.1 3.7 1.9 100.0
5 76 – 33 – 2 – – – 2 14 43 1642
0.3 4.6 – 2.0 – 0.1 – – – 0.1 0.9 2.6 99.9
– 15 – 4 – – – – – – – – 238
– 6.3 – 1.7 – – – – – – – – 100.0
2 8 – – – – – – – – – – 134
1.5 5.9 – – – – – – – – – – 100.0
– 7 – 3 1 – – – – – 2 – 82
– 8.5 – 3.7 1.2 – – – – – 2.4 – 100.0
7 13
3.8 7.0
7 – – – – – – – 3 185
3.8 – – – – – – – 1.6 100.0
%
29
13.9
70
33.5
3 16 49 2
1.4 7.7 23.4 1.0
11 13
5.3 6.2
7
3.3
6 – – – –
2.9 – – – –
6 209
2.8 100
B.S.M.S. Siriwardena et al. / Pathology – Research and Practice 208 (2012) 225–230
S/MA PA DA UA SOT CEOT AOT KCOT AF AFO ODT CCOT DGCT OF OMYX OMF CMB MA CCOC PIOSCC ex OKC PIOSCC ex OC AC AFS PIOC Other Total
Present study
229
230
B.S.M.S. Siriwardena et al. / Pathology – Research and Practice 208 (2012) 225–230
Odontogenic Tumor (AOT) has been re-classified into the epithelium without ectomesenchyme group with the presumption that dysplastic dentin present within the tumor is a result of a metaplastic process rather than an epithelio–ectomesenchymal interaction. All cases of AOT in this series occurred before the age of 50 years, and it is frequently found between 10 and 20 years (70%). Most AOTs were present in the maxilla, with the ratio of 2.3:1. Maxillary AOTs were present in the anterior region, and there is one case presented in the posterior mandible which showed a unilocular radiolucency extending from the premolar to molar region. Similar to other studies, AOT shows a female predilection (2:1) [5–7,10,23]. Another new terminology was CCOT, which was previously defined as calcifying odontogenic cyst (COC). The latter was classified into cystic and solid variants in the past, and the solid type is usually associated with odontogenic hamartomas and referred to as CCOT. The solid lesions with dentinoid formation were named as DGCT, and the lesions with malignant features are termed ghost cell odontogenic carcinoma. There were 24 cases of CCOT (1.4%), which shows a male predilection and was commonly found in the mandible. There were 5 cases of DGCT, and all were in the mandible. The literature indicated that the commonly affected age group is 10–19 (2 cases in this study) although this tumor can occur at any age. Clear cell odontogenic carcinoma (CCOC) is the other entity that the terminology has changed from clear cell odontogenic tumor in the previous classification, and this series reports 5 cases. Malignant OTs Malignant OTs were rare (1.3%), including a single case of metastasizing ameloblastoma [5]. Published reports also stated that malignant odontogenic tumors are rare and represent 1.3–5.2% of the tumors [4,14,16,18]. In this group, 3 cases arose from the pre-existing cysts and 3 cases from ameloblastic carcinomas. In conclusion, the present series is the largest analysis of odontogenic tumors in the world literature. Although odontoma is said to be the commonest in western countries, our results showed ameloblastoma as the commonest followed by KCOT, and the relative frequencies of different tumors have changed significantly as a result of inclusion of KCOT in the new classification. It is interesting to note that few cases of previously reported COCs were reclassified as DGCT. Acknowledgements The authors thank all the Oral and Maxillofacial Surgeons and Dental Surgeons in Sri Lanka. References [1] J.T. Arotiba, J.O. Ogunbiyi, A.E. Obiechina, Odontogenic tumours: a 15-year review from Ibadan, Nigeria, Br. J. Oral Maxillofac. Surg. 35 (5) (1997) 363–367.
[2] R.L. Avelar, A.A. Antunes, T. Santos, E.S. Andrade, E. Dourado, Odontogenic tumors: clinical pathology study of 238 cases, Braz. J. Otorhinolaryngol. 74 (5) (2008) 668–673. [3] L. Barnes, J.W. Evenson, P. Reichart, D. Sidransky, Neoplasms and Tumour like Lesions Arising from Odontogenic Apparatus and Maxillofacial Skeleton: WHO Classification of Head and Neck Tumors, IARC, Lyon, 2005, pp. 284–286. [4] T.D. Daley, G.P. Wysocki, G.A. Pringle, Relative incidence of odontogenic tumors and oral and jaw cysts in a Canadian population, Oral Surg. Oral Med. Oral Pathol. 77 (3) (1994) 276–280. [5] R.K. Dissanayake, P.R. Jayasooriya, D.J. Siriwardena, W.M. Tilakaratne, Review of metastasizing (malignant) ameloblastoma (METAM): pattern of metastasis and treatment, Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endod. 111 (6) (2011) 734–741. [6] L.A. Gaitán-Cepeda, D. Quezada-Rivera, F. Tenorio-Rocha, E.R. Leyva-Huerta, Reclassification of odontogenic keratocyst as a tumour. Impact on the odontogenic tumours prevalence, Oral Dis. 16 (2) (2010) 185–187. [7] M. Guerrisi, M.J. Piloni, A. Keszler, Odontogenic tumors in children and adolescents. A 15-year retrospective study in Argentina, Med. Oral Pathol. Oral Cir. Bucal. 12 (2007) E180–E185. [8] O. Günhan, G. Erseven, S. Ruacan, et al., Odontogenic tumours. A series of 409 cases, Aust. Dent. J. 35 (6) (1990) 518–522. [9] W. Jing, M. Xuan, Y. Lin, et al., Odontogenic tumours: a retrospective study of 1642 cases in a Chinese population, Int. J. Oral Maxillofac. Surg. 36 (1) (2007) 20–25. [10] I.R.H. Kramer, J.J. Pindborg, M. Shear, WHO Histological Typing of Odontogenic Tumours, 2nd ed., Springer-Verlag, Geneva, 1992. [11] A.L. Ladeinde, O.F. Ajayi, M.O. Ogunlewe, et al., Odontogenic tumors: a review of 319 cases in a Nigerian teaching hospital, Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endod. 99 (2) (2005) 191–195. [12] Y. Lu, M. Xuan, T. Takata, et al., Odontogenic tumors. A demographic study of 759 cases in a Chinese population, Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endod. 86 (6) (1998) 707–714. [13] H.Y. Luo, T.J. Li, Odontogenic tumors: a study of 1309 cases in a Chinese population, Oral Oncol. 45 (8) (2009) 706–711. [14] A. Mosqueda-Taylor, C. Ledema-Montes, S. Caballero-Sandoval, J. PortillaRobertson, L.M. Ruiz-Godoy Rivera, A. Meneses-Garcia, Odontogenic tumors in Mexico: a collaborative retrospective study of 349 cases, Oral Surg. Oral Med. Oral Pathol. 84 (6) (1997) 672–675. ˜ E. Escobar, Odontogenic tumors [15] G. Ochsenius, A. Ortega, L. Godoy, C. Penafiel, in Chile: a study of 362 cases, J. Oral Pathol. Med. 31 (7) (2002) 415–420. [16] O. Odukoya, Odontogenic tumors: analysis of 289 Nigerian cases, J. Oral Pathol. Med. 24 (10) (1995) 454–457. [17] C.O. Ogunsalu, Odontogenic tumours from two centres in Jamaica. A 15-year review, West Indian Med. J. 52 (4) (2003) 285–289. [18] H. Okada, H. Yamamoto, W.M. Tilakaratne, Odontogenic tumors in Sri Lanka: analysis of 226 cases, J. Oral Maxillofac. Surg. 65 (5) (2007) 875–882. [19] R.L. Osterne, R.G. Brito, A.P. Alves, R.B. Cavalcante, F.B. Sousa, Odontogenic tumors: a 5-year retrospective study in a Brazilian population and analysis of 3406 cases reported in the literature, Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endod. 111 (4) (2011) 474–481. [20] J.J. Pindborg, I.R.H. Kramer, WHO Histological Typing of Odontogenic Tumours, Jaw Cysts and Allied Lesions, 1st ed., Springer-Verlag, Geneva, 1971. [21] J.N. Santos, L.P. Pinto, C.R. de Figueredo, L.B. de Souza, Odontogenic tumors: analysis of 127 cases, Pesqui. Odontol. Bras. 15 (4) (2001) 308–313. [22] G. Sriram, R.P. Shetty, Odontogenic tumors: a study of 250 cases in an Indian teaching hospital, Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endod. 105 (2008) E14–E21. [23] M.A. Tawfik, M.M. Zyada, Odontogenic tumors in Dakahlia, Egypt: analysis of 82 cases, Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endod. 109 (2) (2010) e67–e73. [24] A. Varkhede, J.V. Tupkari, M. Sardar, Odontogenic tumors: a study of 120 cases in an Indian teaching hospital, Med. Oral Pathol. Oral Cir. Bucal. 16 (7) (2011) e895–e899.
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Pathology – Research and Practice journal homepage: www.elsevier.de/prp
Original article
Relative frequency of odontogenic tumors in Sri Lanka: Analysis of 1677 cases B.S.M.S. Siriwardena, T.M.P.B. Tennakoon, W.M. Tilakaratne ∗ Department of Oral Pathology, Faculty of Dental Sciences, University of Peradeniya,Sri Lanka
a r t i c l e
i n f o
Article history: Received 30 January 2012 Received in revised form 9 February 2012 Accepted 9 February 2012 Keywords: Odontogenic tumors WHO classification Ameloblastoma KCOT Frequency
a b s t r a c t Odontogenic tumors (OTs) constitute a heterogeneous group of lesions with diverse histopathological features and clinical manifestations. The present study is to determine the frequency of odontogenic tumors (OTs) in Sri Lankan population. A total of 1677 cases of OTs were retrieved and analyzed for age, gender and primary site of the tumors. Cases were re-classified according to the 2005 WHO classification of OTs. The relative frequency of different types of tumors was also analyzed and compared with the literature. OTs represent 3.75% of all cases received during a period of 30 years. Ninety-eight percent of these tumors were benign and the rest malignant. Mandible to maxilla ratio is 2.8:1. The posterior part, the molar region, is the most frequently affected site for the mandible whilst it is the anterior region for the maxilla. The age ranges from 1 to 80 years, with a mean age of 30.6 years. Ameloblastoma of solid/multicystic and unicystic types showed a high preponderance for the mandible (>90%) with a ratio of 12.9:1 and 10.8:1, respectively. Out of 1677 cases, 48.7% were ameloblastoma, and other tumors, such as keratocystic odontogenic tumor (KCOT) and odontoma, were 25.7% and 10.1%, respectively. There is a significant change in the frequency of OTs after the inclusion of odontogenic keratocyst as a tumor. Although odontoma is said to be the commonest in western countries, our results showed ameloblastoma as the commonest followed by KCOT, and the relative frequencies of different tumors have changed significantly as a result of inclusion of KCOT in the new classification. © 2012 Elsevier GmbH. All rights reserved.
Introduction Odontogenic tumors (OT) are lesions derived from epithelial, ectomesenchymal and/or mesenchymal elements of the toothforming apparatus. It constitutes a heterogeneous group of lesions with diverse histopathological features and clinical manifestations, and the spectrum of the biological behavior of these lesions ranges from hamartomatous or non-neoplastic tissue proliferations to malignant neoplasms. The majority of studies [8,12,17] from various parts of the world were based on the 1971 [20] and 1992 [10] WHO histological classification, and few on the recently published updated edition of WHO [3] classification. Several retrospective studies carried out in Asia, Africa, Europe and America reveal that differences exist in the relative frequency of various histological types [7,9,13,16,19,22]. Therefore, the purpose of this study was to determine the relative frequency of odontogenic tumors with regard to the new WHO classification and to compare these data with previously published reports after the 2005 OT classification from other parts of the world. Further, we intended to analyze the changing pattern of
frequency with the inclusion of keratocystic odontogenic tumor (KCOT) in the new classification. Materials and methods The surgical histopathology records of the Department of Oral Pathology, Faculty of Dental Sciences, University of Peradeniya were reviewed retrospectively from January 1980 to August 2011. A total of 1677 cases of OTs were collected and reviewed. Recurrent tumors were considered as a single case. Two investigators (WMT, SS) evaluated the hematoxylin and eosin-stained sections, and the diagnosis in each case was either re-confirmed or modified in accordance with the third edition of the WHO classification. The frequency and distribution regarding age, sex and primary site of the lesion were analyzed and compared with the studies which were published before and after 2005 WHO classification in the English literature. Each jaw was divided into three anatomical parts as anterior, premolar and molar in order to decide the location of the tumor. Results
∗ Corresponding author. Tel.: +94 812397435; fax: +94 81 2388948. E-mail address: [email protected] (W.M. Tilakaratne). 0344-0338/$ – see front matter © 2012 Elsevier GmbH. All rights reserved. doi:10.1016/j.prp.2012.02.008
During the period of 30 years, a total of 44,458 biopsies were received, and 3.8% of them were OTs. Of a total of 1677 cases
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B.S.M.S. Siriwardena et al. / Pathology – Research and Practice 208 (2012) 225–230
Table 1 Frequency and gender distribution of odontogenic tumors. Abbreviation Benign Solid/multicystic ameloblastoma Peripheral ameloblastoma Desmoplastic ameloblastoma Unicystic ameloblastoma Squamous odontogenic tumor Calcifying epithelial odontogenic tumor Adenomatoid odontogenic tumor Keratocystic odontogenic tumor Ameloblastic fibroma Ameloblastic fibro-odontoma Odontoma Calcifying cystic odontogenic tumor Dentinogenic ghost cell tumor Odontogenic fibroma Odontogenic myxoma Odontogenic myxo fibroma Cementoblastoma Malignant Malignant ameloblastoma Clear cell odontogenic carcinoma PIOSCC arising from OKC PIOSCC arising from odontogenic cysts Ameloblastic carcinoma Ameloblastic fibrosarcoma Primary intraosseous carcinoma
Total cases
S/MA PA DA UA SOT CEOT AOT KCOT AF AFO ODT CCOT DGCT OF OMYX OMF CMB MA CCOC PIOSCC ex OKC PIOSCC ex OC AC AFS PIOC
Female
%
Male
%
Male:Female
520 6 29 261 7 25 78 431 15 9 169 24 5 7 64 3 1
259 4 15 124 6 15 52 192 5 5 82 7 2 4 32 3 1
49.8 66.7 51.7 47.5 85.7 60.0 66.7 44.5 33.3 55.6 48.5 29.1 40.0 57.1 50.0 100.0 100.0
261 2 14 137 1 10 26 239 10 4 87 17 3 3 32 0 0
50.2 33.3 48.3 52.5 14.3 40.0 33.3 55.5 66.7 44.4 51.5 70.8 60.0 42.9 50.0 0.0 0.0
1:1 1:2 1:1.1 1.1:1 1:6 1:1.5 1:2 1.2:1 2:1 1:1.3 1.1:1 2.4:1 1.5:1 1:1.3 1:1 NA NA
1 5 2 1 3 1 10
1 3 0 0 2 0 5
100.0 60.0 0.0 0.0 66.7 0.0 50.0
0 2 2 1 1 1 5
0.0 40.0 100.0 100 33.3 100.0 50.0
NA 1:1.5 NA NA 1:2 NA 1:1
PIOSCC – primary intra-osseous squamous cell carcinoma, NA – not applicable.
of OTs, 1654 (98.6%) were benign and 23 (1.4%) were malignant. Ameloblastoma was the most common tumor (48.7%), and the solid/multicystic (S/MA) variant was the commonest type (31%) followed by KCOT (25.7%) and odontoma (10%). Table 1 shows the frequency and gender distribution of OTs. Out of all S/MA, 31.9% and 34.2% were plexiform and follicular ameloblastoma, respectively. There were 858 males and 819 females. Although there is no gender predilection (1:1) for most OTs, there is a female preponderance for squamous odontogenic tumor (SOT). The age of the patients ranges from 1 year to 86 years, with a mean age of 30.6
years. The majority of cases were distributed between age 10 and 49 with a peak incidence in the second and third decades (Table 2). As described in the literature, the mean age for odontoma, adenomatoid odontogenic tumors (AOT) and unicystic ameloblastoma (UA) was 19, 18 and 29.9 years, respectively. Desmoplastic ameloblastoma (DA) and peripheral ameloblastoma (PA) tend to occur in older individuals. Most malignant OTs also predominantly occurred in older patients (Table 2). There were 5 cases of Dentinogenic ghost cell tumor (DGCT), which is a new entity according to the 2005 WHO classification. The affected age groups were 10–19 (2 cases)
Table 2 Distribution of odontogenic tumors in different age groups. Age group (years)
Solid/multicystic ameloblastoma Peripheral ameloblastoma Desmoplastic ameloblastoma Unicystic ameloblastoma Squamous odontogenic tumor Calcifying epithelial odontogenic tumor Adenomatoid odontogenic tumor Keratocystic odontogenic tumor Ameloblastic fibroma Ameloblastic fibro-odontoma Odontoma Calcifying cystic odontogenic tumor Dentinogenic ghost cell tumor Odontogenic fibroma Odontogenic myxoma Odontogenic myxo fibroma Cementoblastoma Malignant ameloblastoma Clear cell odontogenic carcinoma Carcinoma arising from OKC PIOSCC arising from odontogenic cysts Ameloblastic carcinoma Ameloblastic fibrosarcoma Primary intraosseous carcinoma Total
0–9
10–19
20–29
30–39
40–49
50–59
60–69
70–79
80–89
NS
Total
Mean
6 – – 7 – – 2 8 2 7 16 2 – 1 5 – – – 1 – – – – – 57
82 – – 68 1 5 53 78 3 1 94 4 2 2 15 2 – – – – – – – – 410
139 – 3 66 – 8 14 124 3 – 31 2 – – 24 – 1 – – – – 1 1 – 417
98 1 3 49 2 2 4 87 1 – 8 2 – 1 9 – – – – – – – – – 267
75 3 9 36 – 3 3 55 1 – 5 3 – – 2 1 – 1 1 1 – – – 4 203
57 1 6 12 3 5 – 41 – – 5 4 – 3 4 – – – 2 1 1 – – 1 146
34 – 6 13 1 – – 20 4 – 3 4 1 – 1 – – – – – – 2 – 5 94
10 – – 4 – – – 6 – – 1 3 2 – 3 – – – 1 – – – – – 30
4 – 1 2 – – – 1 – – – – – – – – – – – – – – – – 8
15 1 1 4 – 2 2 11 1 1 6 – – – 1 – – – – – – – – – 45
520 6 29 261 7 25 78 431 15 9 169 24 5 7 64 3 1 1 5 2 – 3 1 10 1677
34.2 39.0 47.1 29.9 45.3 30.4 18.0 31.3 29.4 6.0 19.0 43.0 46.0 33.0 27.0 25.0 29.0 43.0 44.8 55.5 57.0 48.7 22.0 55.8 30.8
PIOSCC – primary intra-osseous squamous cell carcinoma.
B.S.M.S. Siriwardena et al. / Pathology – Research and Practice 208 (2012) 225–230
Frequency of common OT before and aer 2005 WHO classificaon
50
44
45 40
35.8
2005 WHO classificaon
35 30
1992 WHO classificaon
24.1
25 20
14
15 10
3.7
5
6
8.9 5.3
0 Ameloblastoma
Odontoma
AOT
O Myxoma O.Myxoma
Fig. 1. Changing pattern of OTs after inclusion of KCOT into 2005 WHO classification.
years and 60–79 (3 cases) years. The tumor shows mandibular predilection. The mandible was the mostly affected site of occurrence for most OTs, and for overall it is 62.7% with a ratio of 2.8:1 (Table 3). Ameloblastoma of solid/multicystic and unicystic types showed a higher preponderance for the mandible (>90%) with a ratio of 12.9:1 and 10.8:1, respectively. In accordance with the literature, AOT and odontoma show a higher maxillary predilection with a ratio of 2.3:1 and 6.6:1, respectively. Desmoplastic ameloblastoma tend to occur commonly in anterior maxilla. Generally, except odontoma and AOT, the OTs were more commonly encountered in the posterior part of the jaws. The majority of OTs occurred in the posterior part of the mandible, including the premolar and molar region in contrast to maxilla, where anterior maxilla was affected more frequently. There is a slight predominance for the right side of both jaws. Tumors that involved more than two zones and some extending to the opposite side were mainly ameloblastoma (S/MA & UA) and KCOT. The cases that involved more than one zone in mandible were 45.5%, and in maxilla it was 31.2%. The relative frequency of OTs found in the present study was compared with studies reported in the literature which followed the new WHO 2005. OT classification is given in Table 4. There were only 7 studies [2,6,9,13,19,23,24] available in the English literature, and according to these, ameloblastoma is the commonest odontogenic tumor except two studies which revealed odontoma and KCOT as the commonest. The second most common tumor is KCOT followed by odontoma. It is interesting to note that the frequency of ameloblastoma in comparison to other OTs has reduced significantly, as a result of the inclusion of OKC as a benign tumor in the 2005 WHO classification (Fig. 1). There were 22 cases of malignant OTs comprising mostly primary intraosseous carcinomas (10 cases) and clear cell odontogenic carcinoma (5 cases). A single case of metastasizing ameloblastoma (malignant ameloblastoma) is also reported in this study. Discussion Odontogenic tumors develop from the tissues of tooth formation and constitute a diverse group of lesions. The classification of OTs in the revised 2nd edition of WHO (1992) was widely used in previous studies, and there were only a few studies available [2,6,9,13,19,23,24] in accordance with the updated edition in 2005. The first classification of this heterogeneous group of lesions was published in 1971 [20], and an updated second edition of the WHO classification was published in 1992 [10]. Due to advances in immunohistochemistry and molecular biology during the last decade, a revision of the 1992 edition of the WHO classification was proposed by Philipsen and Reichart and published in 2005 [3].
227
The present study analyzed the largest series of OTs, comprising 1677 cases reported in the literature despite the fact that the series is from a single institute. Jing et al., in 2007, analyzed 1642 cases of OTs over a period over 53 years [13]. All the cases presented in our series (30-year period) were re-evaluated and re-classified according to the 2005 WHO classification. In the present study, ameloblastoma was the commonest OT followed by KCOT and odontoma. These results were consistent with the data from Brazil [19], China [9,13] and Africa [23]. Odontoma was the commonest OT reported in the Western world [6]. It can be hypothesized that the discrepancy may be due to geographic variation. It is reported that in some countries, odontomas are underestimated due to poor patient compliance, absence of clinical symptoms and self limited growth in some tumors. Therefore, many cases are managed by peripheral units and may be inadequately documented or may not be sent for histopathological investigations. Age/gender distribution Although there is no significant gender predilection for OTs in this present study, there is a female preponderance reported in Chile, Mexico and Nigeria [1,15,21]. A marked female predilection was observed in SOT, which was 6:1. Similarly, PA, AOT and CEOT showed a slight female preponderance. In contrast, calcifying cystic odontogenic tumor (CCOT), DGCT and ameloblastic fibroma occurred predominantly in males. The mean age was 30.6 years, and the majority of the cases occurred between age 10 and 49 with a peak incidence in the 3rd decade of life. S/MA, KCOT showed a marked prevalence in this age range. As accepted globally, several OTs, such as odontoma, AOTs and UAs, were more pronounced in the 2nd decade of life. Primary site In agreement with the literature, OTs are present mostly in the mandible, especially in the posterior zone (molar region), and a significantly higher number of OTs, mostly ameloblastoma, involve more than one zone. The mean age of ameloblastoma in the present study was 34.2 years, which falls within the range of previously published studies [1,9,11,16]. More than 90% of S/MA and UA occurred in the mandible, especially in the posterior region, and the finding was comparable with the published studies [11,16]. Frequency As odontogenic keratocyst was renamed as KCOT in the current WHO classification, the frequency of OTs has been changed. In the studies done so far with the new classification, including the present study, KCOT is the 2nd most common OT, and it amounts to 25.7% in the present series. Other studies also showed the frequency of KCOT ranging from 19.5% to 52% [9,13,19,23]. The available reports have not sub-classified ameloblastoma as SM/A, UA, DA according to the new classification, making it difficult to comment on the frequency of subtypes globally. According to this study, out of the 4 types, 63.7% of them were S/MA and 31.9% were UA. In the present series, 3.8% of the cases were odontogenic myxomas. Ameloblastic fibroma and ameloblastic fibro odontoma together account for 1.4%. New additions/changes in the 2005 WHO classification of OTs Except KCOT, which is the major influence on changing the frequency of OTs, there are other tumors that have changed their name or the position in the 2005 WHO classification of OTs. Adenomatoid
228
Table 3 Site distribution of odontogenic tumors. Mandible Anta
a b c d e f g h i
Anterior. Posterior. Total. Left. Right. Mandible. Maxilla. Not specified. Not applicable.
Tc
Ld
Re
L
R
L
R
L
R
mdf
2 1 – 1 – – 1 9 – – 3 0 1 – – – – – – – – – – – 18
7 – – 4 – 1 2 10 – – 1 2 1 – – – – – – – 1 – – – 28
34 – 1 15 – – 2 18 – – 6 2 – 2 2 – – – 2 – – – – – 84
29 – – 18 – 1 4 34 – 2 8 4 2 – 4 – – – 1 – – – – – 107
43 – – 36 – 1 – 72 1 2 10 1 – – 4 – – – – – – 1 – – 171
44 1 1 36 – 1 1 60 2 – 12 – – – 3 – – 1 – 1 – – – 3 166
71 – – 28 1 – – 19 1 – 3 2 – 1 2 2 – – 1 – – – – 1 132
68 – 5 56 – 5 1 29 – – 1 3 – – 3 – – – – – – – – 1 172
77 1 6 33 1 5 5 34 3 – 2 2 1 – 3 – – – – – – – – 1 174
375 3 13 227 2 14 16 285 7 4 46 16 5 3 21 2 – 1 4 1 1 1 – 6 1053
%
92.8 60.0 46.4 91.5 50.0 73.7 30.8 74.4 53.8 50.0 30.3 70.4 100 50.0 44.7 100. – 100 80.0 50.0 100 33.3 – 73.9
Man:Max
Ant
Middle
Post
T
L
R
L
R
L
R
L
R
mxg
2 – 1 1 – – 5 5 – – 23 1 – – 1 – – – – – – – – – 39
1 1 3 1 – – 14 20 – 2 44 1 – – 1 – – – – – – – – – 88
2 – 1 3 – – 5 9 2 1 10 1 – 2 4 – – – – – – – 1 – 41
4 – 2 5 1 3 4 9 2 1 6 – – – 1 – – – – – – – – – 38
2 – – – – – – 10 1 – 5 – – – 3 – – – – – – – – – 21
3 – – 1 – – – 13 – – 3 1 – – 3 – – – – – – – – – 24
3 – 5 3 – 1 5 9 – – 1 1 – – 7 – 1 – 1 – – 2 – 4 43
10 – 1 3 – 1 3 15 1 – 5 2 – – 5 – – – – – – – – – 46
2 1 2 4 1 – 8 – – 9 1 – 1 1 – – – – 1 – – – – 31
% NSh
29 2 15 21 2 5 36 98 6 4 106 8 – 3 26 – 1 – 1 1 – 2 1 4 371
7.2 40.0 53.6 8.5 50.0 26.3 69.2 25.6 46.2 50.0 69.7 29.6 – 50.0 55.3 – 100 – 20.0 50.0 – 66.7 100 26.1
116 1 1 13 3 6 26 48 2 1 17 – – 1 17 1 – – – – – – – – 253
12.9:1 1.5:1 1:1.2 10.8:1 1:1 2.8:1 1:2.3 2.9:1 1.2:1 1:1 1:6.6 3:1 NA 1:1 1:1.2 NAi NA NA 4:1 1:1 NA 1:2 NA 1.5:1 2.8:1
B.S.M.S. Siriwardena et al. / Pathology – Research and Practice 208 (2012) 225–230
S/MA PA DA UA SOT CEOT AOT KCOT AF AFO ODT CCOT DGCT OF OMYX OMF CMB MA CCOC PIOSCC ex OKC PIOSCC ex OC AC AFS PIOC Total
Maxilla Postb
Middle
Table 4 Comparison of the present study with the studies published after 2005 WHO classification. %
520 6 29 261 7 25 78 431 15 9 169 24 5 7 64 3 1 1 5 2 1 3 1 10 – 1677
31.0 0.4 1.7 15.6 0.4 1.5 4.7 25.7 0.9 0.5 10.1 1.4 0.2 0.4 3.8 0.2 0.06 0.06 0.3 0.1 0.06 0.2 0.06 0.6 – 100.04
Hai-Yan et al.
%
Jing et al.
%
Avelar et al.
%
GaitanCepeda et al.
%
Tawfik et al.
%
Osterne et al.
%
Gill et al.
316 6 7 149 – 6 27 507 13 12 80 26
24.1 0.5 0.5 11.4 – 0.5 2.1 38.7 1.0 0.9 6.1 2.0
661 – – – 3 10 68 588 19 4 78 36
40.3 – – – 0.2 0.6 4.1 35.8 1.2 0.2 4.7 2.2
57 – – – 1 5 13 69 4 1 54 15
23.7 – – – 0.4 2.0 5.4 30.0 1.7 0.4 22.1 6.3
25 – – – – 2 2 53 – – 42 –
18.7 – – – – 1.5 1.5 39.6 – – 31.3 –
34 – – – – 3 3 16 2 – 11 –
41.5 – – – – 3.7 3.7 19.5 2.4 – 13.4 –
54 – – – – 1 1 52 4 – 36 7
29.2 – – – – 0.5 0.5 28.1 2.2 – 19.5 3.8
21 34 – 22 – 8 – – – 1 49 25 1309
1.6 2.6 – 1.7 – 0.6 – – – 0.1 3.7 1.9 100.0
5 76 – 33 – 2 – – – 2 14 43 1642
0.3 4.6 – 2.0 – 0.1 – – – 0.1 0.9 2.6 99.9
– 15 – 4 – – – – – – – – 238
– 6.3 – 1.7 – – – – – – – – 100.0
2 8 – – – – – – – – – – 134
1.5 5.9 – – – – – – – – – – 100.0
– 7 – 3 1 – – – – – 2 – 82
– 8.5 – 3.7 1.2 – – – – – 2.4 – 100.0
7 13
3.8 7.0
7 – – – – – – – 3 185
3.8 – – – – – – – 1.6 100.0
%
29
13.9
70
33.5
3 16 49 2
1.4 7.7 23.4 1.0
11 13
5.3 6.2
7
3.3
6 – – – –
2.9 – – – –
6 209
2.8 100
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S/MA PA DA UA SOT CEOT AOT KCOT AF AFO ODT CCOT DGCT OF OMYX OMF CMB MA CCOC PIOSCC ex OKC PIOSCC ex OC AC AFS PIOC Other Total
Present study
229
230
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Odontogenic Tumor (AOT) has been re-classified into the epithelium without ectomesenchyme group with the presumption that dysplastic dentin present within the tumor is a result of a metaplastic process rather than an epithelio–ectomesenchymal interaction. All cases of AOT in this series occurred before the age of 50 years, and it is frequently found between 10 and 20 years (70%). Most AOTs were present in the maxilla, with the ratio of 2.3:1. Maxillary AOTs were present in the anterior region, and there is one case presented in the posterior mandible which showed a unilocular radiolucency extending from the premolar to molar region. Similar to other studies, AOT shows a female predilection (2:1) [5–7,10,23]. Another new terminology was CCOT, which was previously defined as calcifying odontogenic cyst (COC). The latter was classified into cystic and solid variants in the past, and the solid type is usually associated with odontogenic hamartomas and referred to as CCOT. The solid lesions with dentinoid formation were named as DGCT, and the lesions with malignant features are termed ghost cell odontogenic carcinoma. There were 24 cases of CCOT (1.4%), which shows a male predilection and was commonly found in the mandible. There were 5 cases of DGCT, and all were in the mandible. The literature indicated that the commonly affected age group is 10–19 (2 cases in this study) although this tumor can occur at any age. Clear cell odontogenic carcinoma (CCOC) is the other entity that the terminology has changed from clear cell odontogenic tumor in the previous classification, and this series reports 5 cases. Malignant OTs Malignant OTs were rare (1.3%), including a single case of metastasizing ameloblastoma [5]. Published reports also stated that malignant odontogenic tumors are rare and represent 1.3–5.2% of the tumors [4,14,16,18]. In this group, 3 cases arose from the pre-existing cysts and 3 cases from ameloblastic carcinomas. In conclusion, the present series is the largest analysis of odontogenic tumors in the world literature. Although odontoma is said to be the commonest in western countries, our results showed ameloblastoma as the commonest followed by KCOT, and the relative frequencies of different tumors have changed significantly as a result of inclusion of KCOT in the new classification. It is interesting to note that few cases of previously reported COCs were reclassified as DGCT. Acknowledgements The authors thank all the Oral and Maxillofacial Surgeons and Dental Surgeons in Sri Lanka. References [1] J.T. Arotiba, J.O. Ogunbiyi, A.E. Obiechina, Odontogenic tumours: a 15-year review from Ibadan, Nigeria, Br. J. Oral Maxillofac. Surg. 35 (5) (1997) 363–367.
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