Odontogenic tumors: A review of 93 cases in the Vidharba region of Maharashtra.

BACKGROUND: Tumors of the odontogenic origin (OTs) are rare tumors accounting for 1% of all the jaw tumors in the oral cavity. The behavior of these tumors ranges from hamartomatous proliferation to malignant neoplasm. AIM: The aim of this study was to determine the epidemiological data, clinical and histopathological picture with variants of the OTs diagnosed at our institute in the Vidarbha region. SETTINGS AND
DESIGN: A retrospective study was carried out with the permission from the institutional authorities. The archival records of the Department of Oral Pathology and Microbiology were reviewed.
MATERIALS AND METHODS: A total of 93 cases of OTs were reviewed retrospectively from the archival records of the Department of Oral Pathology and Microbiology from January 2008 to December 2018. Statistical analysis was carried out and the determination of the age, gender, jaw, site, diagnosis, variants and year-wise distribution of odontogenic lesions was taken out using the SPSS software.
RESULTS: Ninety-three cases of OTs were identified. The most common OT identified was ameloblastoma (n = 37/39.7%) followed by keratocystic OT (n = 8/8.6%), adenomatoid OT (n = 7/7.5%) and odontome (O) (n = 6/6.4%). The tumors were diagnosed in a wide age range from 1st to 3rd decennium of life. The mandibular posterior region was the most commonly affected anatomical site with the maxilla and mandible ratio of 1:6.
CONCLUSION: OTs were found to be rare in the sample studied. The findings of the study were in concordance to those of Asian and African series. Variations were shown from the series of American reports, and further investigations are needed for this disparity. Copyright:

INTRODUCTION

Tumors of odontogenic origin (OTs) found in the maxillofacial region are uncommon group of tumors exhibiting heterogeneous behavior ranging from hamartomatous proliferation to malignant neoplasms with the potential of metastasis.[12] The OTs originates from epithelial and/or mesenchymal component of the tissue surrounding the teeth. The OTs are seen intraosseously in the jaw bones or extraosseously in the alveolar mucosa of the tooth-bearing apparatus.[34] It represents 1% of all the tumors of the jaw. The differences in the relative frequencies of these tumors is shown in the literature.[35]

Similar to the process of normal odontogenesis, OTs are capable of undergoing inductive mechanism where in interactions between odontogenic epithelium and ectomesenchyme takes place. Hence, the classification of OTs is introduced based on this mechanism. In 1971, the “histological typing of OTs” was first published by the World Health Organization (WHO).[6] The first edition was revised and the second edition was published in the year 1992.[7] In this classification, calcifying odontogenic cyst was included under OT. The third edition was published in 2005 where odontogenic keratocyst was reclassified as keratocystic OT (KCOT) with increased prevalence and distribution of OTs.[3] The fourth edition was published in 2017 to simplify the terminologies and classification reflecting their proper biological behavior. It included main differences from the 3rd edition (2005) introducing a new classification of odontogenic cysts, “reclassified” as OTs, and some new entities.[8]

The frequency of OTs occurring in different ethnic groups from different geographical areas of the world have been documented. The frequency of these lesions is seen occurring mostly among Americans and Africans according to the available literature. Many epidemiological studies have been reported on OTs from different parts of the world, but the studies reported from the Indian subcontinent are very few. Epidemiological studies help in assessing the concern for the disease, health-care planning and estimating the quantum for reducing the disease stress. Hence, this study was performed to determine the epidemiological data, clinical and histopathological picture of the OTs diagnosed at our institute over the period of January 2008 to December 2018 with comparison of these data to the previous reports.

MATERIALS AND METHODS

A retrospective study was carried out with the permission from the institutional authorities. The archival records of the Department of Oral Pathology and Microbiology were reviewed retrospectively for all the OTs occurring in the oral cavity from January 2008 to December 2018. The study variables were age, gender, jaw, site and histopathologic features with variants of OTs. The histopathological diagnosis was made according to the 2005 WHO classification of OTs.

Statistical analysis was carried out and determination of the age, gender, jaw, site, diagnosis, variants and year-wise distribution of odontogenic lesions was taken out.

RESULTS

According to the retrospective study, the age distribution showed a peak occurrence of the OT in the 1st–3rd decennium of life. The type of lesions encountered is shown in the tabular form [Table 1 and Graph 1]. The most common OT diagnosed was ameloblastoma with 27% of cases occurring in the 2nd–3rd decennium of life and 18.9% in the 3rd–4th decennium of life [Table 2 and Graph 2]. Unicystic ameloblastoma (UA) which is a rare type of ameloblastoma was mostly seen in the 1st–2nd decennium of life [Table 2]. The second-most common OT was KCOT showing equal percentage of cases, i.e., 37.5% in both 1st–2nd and 2nd–3rd decennium [Table 2]. Adenomatoid OT (AOT) was the third-most common tumor showing 85.7% of cases occurring in the 1st–2nd decade [Table 2]. Odontome (O) was the fifth-most common tumor showing equal percentage, i.e., 33.3% of cases in the 1st–2nd and 4th–5th decennium [Table 2]. Among 93 OTs, 47 cases were seen in males and 46 cases in females, with a ratio of 1:1 [Table 3 and Graph 3]. All the cases diagnosed were benign except 4 cases diagnosed with ameloblastic carcinoma. According to the study, 80 cases of OTs affected the mandible and 13 cases affected maxilla, with an overall mandible: Maxilla ratio of 1:6 [Table 4 and Graph 4]. The mandible was most commonly affected jaw by OTs. KCOT showed high predilection with 100% occurrence in the mandibular posterior region [Table 5 and Graph 5]. This was followed by UA affecting the mandible with 95.2% (posterior region 90.5%) and ameloblastoma with 91.9% (posterior region 86.5%) [Table 5]. AOT showed high predilection for maxilla with 57.1% (anterior region 100%) [Table 5]. O equally affected both the maxilla and the mandible with 50% (50% anterior and 50% posterior region) [Tables 4 and 5].

Table 1

Type of lesions encountered

Diagnosis	Number of lesions diagnosed	Variants
Ameloblastoma	37	Hemangiomatous-1
		Dentinoid-1
UA	21	Plexiform-2
AOT	7	-
CEOT	2	Clear cell-1
CO	6	-
OM	3	-
AC	4	-
OFM	1	-
OF	3	-
KCOT	8	-
AF	1	-
Total	93	-

UA: Unicystic ameloblastoma, AOT: Adenomatoid odontogenic tumor, CEOT: Calcifying epithelial odontogenic tumor, OM: Odontogenic myxoma, AC: Ameloblastic carcinoma, KCOT: Keratocystic Odontogenic tumor, AF: Ameloblastic fibroma, OF: Odontogenic fibro, OFM: Odontogenic fibromyxoma, CO: Compound Odontome

Graph 1

Various lesions encountered

Table 2

Age-wise distribution of odontogenic tumours

Diagnosis	Years							Total (%)
	≤10 (%)	11-20 (%)	21-30 (%)	31-40 (%)	41-50 (%)	51-60 (%)	>60 (%)
Ameloblastoma	0 (0.0)	5 (13.5)	10 (27.0)	7 (18.9)	6 (16.2)	3 (8.1)	6 (16.2)	37 (100.0)
UA	1 (4.8)	7 (33.3)	6 (28.6)	2 (9.5)	0 (0.0)	4 (19.0)	1 (4.8)	21 (100.0)
AOT	0 (0.0)	6 (85.7)	1 (14.3)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	7 (100.0)
CEOT	0 (0.0)	0 (0.0)	1 (50.0)	0 (0.0)	0 (0.0)	0 (0.0)	1 (50.0)	2 (100.0)
O	0 (0.0)	2 (33.3)	1 (16.7)	1 (16.7)	2 (33.3)	0 (0.0)	0 (0.0)	6 (100.0)
OM	0 (0.0)	1 (33.3)	2 (66.7)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	3 (100.0)
AC	0 (0.0)	1 (25.0)	1 (25.0)	0 (0.0)	1 (25.0)	0 (0.0)	1 (25.0)	4 (100.0)
OFM	0 (0.0)	0 (0.0)	1 (100.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	1 (100.0)
OF	0 (0.0)	1 (33.3)	133.3	1 (33.3)	0 (0.0)	0 (0.0)	0 (0.0)	3 (100.0)
KCOT	0 (0.0)	3 (37.5)	3 (37.5)	1 (12.5)	0 (0.0)	1 (12.5)	0 (0.0)	8 (100.0)
AF	0 (0.0)	1 (100.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	1 (100.0)
Total	1 (1.1)	27 (29.0)	27 (29.0)	12 (12.9)	9 (9.7)	8 (8.6)	9 (9.7)	93 (100.0)

UA: Unicystic ameloblastoma, AOT: Adenomatoid odontogenic tumor, CEOT: Calcifying epithelial odontogenic tumor, OM: Odontogenic myxoma, AC: Ameloblastic carcinoma, KCOT: Keratocystic Odontogenic tumor, AF: Ameloblastic fibroma, OF: Odontogenic fibro, OFM: Odontogenic fibromyxoma, O: Odontome

Graph 2

Age-wise distribution of odontogenic tumours

Table 3

Gender-wise distribution of odontogenic tumors

Diagnosis	Gender		Total (%)
	Male (%)	Female (%)
Ameloblastoma	19 (51.4)	18 (48.6)	37 (100.0)
UA	14 (66.7)	7 (33.3)	21 (100.0)
AOT	1 (14.3)	6 (85.7)	7 (100.0)
CEOT	0 (0.0)	2 (100.0)	2 (100.0)
CO	4 (66.7)	2 (33.3)	6 (100.0)
OM	1 (33.3)	2 (66.7)	3 (100.0)
AC	2 (50.0)	2 (50.0)	4 (100.0)
OFM	1 (100.0)	0 (0.0)	1 (100.0)
OF	2 (66.7)	1 (33.3)	3 (100.0)
KCOT	3 (37.5)	5 (62.5)	8 (100.0)
AF	0 (0.0)	1 (100.0)	1 (100.0)
Total	47 (50.5)	46 (49.5)	93 (100.0)

UA: Unicystic ameloblastoma, AOT: Adenomatoid odontogenic tumor, CEOT: Calcifying epithelial odontogenic tumor, OM: Odontogenic myxoma, AC: Ameloblastic carcinoma, KCOT: Keratocystic Odontogenic tumor, AF: Ameloblastic fibroma, OF: Odontogenic fibro, OFM: Odontogenic fibromyxoma, CO: Compound Odontome

Graph 3

Gender-wise distribution of odontogenic tumors

Table 4

Distribution of odontogenic tumors according to the jaw affected

Diagnosis	Jaw		Total (%)
	Maxilla (%)	Mandible (%)
Ameloblastoma	3 (8.1)	34 (91.9)	37 (100.0)
UA	1 (4.8)	20 (95.2)	21 (100.0)
AOT	4 (57.1)	3 (42.9)	7 (100.0)
CEOT	1 (50.0)	1 (50.0)	2 (100.0)
CO	3 (50.0)	3 (50.0)	6 (100.0)
OM	1 (33.3)	2 (66.7)	3 (100.0)
AC	0 (0.0)	4 (100.0)	4 (100.0)
OFM	0 (0.0)	1 (100.0)	1 (100.0)
OF	0 (0.0)	3 (100.0)	3 (100.0)
KCOT	0 (0.0)	8 (100.0)	8 (100.0)
AF	0 (0.0)	1 (100.0)	1 (100.0)
Total	13 (14.0)	80 (86.0)	93 (100.0)

UA: Unicystic ameloblastoma, AOT: Adenomatoid odontogenic tumor, CEOT: Calcifying epithelial odontogenic tumor, OM: Odontogenic myxoma, AC: Ameloblastic carcinoma, KCOT: Keratocystic Odontogenic tumor, AF: Ameloblastic fibroma, OF: Odontogenic fibro, OFM: Odontogenic fibromyxoma, CO: Compound Odontome

Graph 4

Distribution of odontogenic tumors according to the jaw affected

Table 5

Distribution of odontogenic tumors according to the site involved

Diagnosis	Site		Total (%)
	Anterior (%)	Posterior (%)
Ameloblastoma	5 (13.5)	32 (86.5)	37 (100.0)
UA	2 (9.5)	19 (90.5)	21 (100.0)
AOT	7 (100.0)	0 (0.0)	7 (100.0)
CEOT	1 (50.0)	1 (50.0)	2 (100.0)
CO	3 (50.0)	3 (50.0)	6 (100.0)
OM	0 (0.0)	3 (100.0)	3 (100.0)
AC	0 (0.0)	4 (100.0)	4 (100.0)
OFM	0 (0.0)	1 (100.0)	1 (100.0)
OF	2 (66.7)	1 (33.3)	3 (100.0)
KCOT	0 (0.0)	8 (100.0)	8 (100.0)
AF	1 (100.0)	0 (0.0)	1 (100.0)
Total	21 (22.6)	72 (77.4)	93 (100.0)

UA: Unicystic ameloblastoma, AOT: Adenomatoid odontogenic tumor, CEOT: Calcifying epithelial odontogenic tumor, OM: Odontogenic myxoma, AC: Ameloblastic carcinoma, KCOT: Keratocystic Odontogenic tumor, AF: Ameloblastic fibroma, OF: Odontogenic fibro, OFM: Odontogenic fibromyxoma, CO: Compound Odontome

Graph 5

Distribution of odontogenic tumors according to the site involved

DISCUSSION

Ameloblastoma was the most common OT diagnosed in this study with 39.7% and is similar to other studies from Asian[910] and African[1112] countries. The ameloblastomas mostly affect angle and ramus region of the mandible. There are three forms of ameloblastomas, namely multicystic (solid), peripheral and unicystic type. The UA which is a rare form of ameloblastoma accounts for 22.5% and is mostly seen in the 1–2 decennium.

The prevalence of OTs has increased after the inclusion of the odontogenic keratocyst in 2005 WHO classification as KCOT. In this study, KCOT was the second most commonly occurring OT with 8.6%. The most common OT presented in the studies from the American countries was O followed by ameloblastoma.[1314] In this study, odontoma is in the fourth position following ameloblastoma and KCOT, with a frequency of 6.4%. The reason behind may be the lack of routine dental checkup with radiographs in the Asian and African population. These tumors are unnoticed for years, and after surgical removal probably the specimen is not sent for histopathological examination.

AOT showed a frequency of 7.5% which is similar to studies from China.[1015] AOT showed a higher frequency of 9% in the epidemiological studies from other parts of India.[16] To prove whether a racial difference exists, follow-up studies are required for the occurrence of different types of OTs in a given population.

Odontogenic myxoma (OM) showed a frequency of 3.2% in this study. The value is lower compared to previous studies. OM showed a frequency of 6.5–17.7% according to the retrospective studies from Brazil,[9] Nigeria,[17] and Mexico.[18] The frequency range of OM in China[10] and Sri Lanka[19] was in the range of 2.6%–4.9%. Higher frequency of OM was also shown from other Indian studies.[16] The low incidence of OM needs further investigation.

According to the study, the incidence of OTs was mostly seen in the 1st–3rd decades of life and is similar to other studies from India[5] and Nigeria[17] China.[15] The mean age less than a decade was shown from studies of Brazil[11] and Chile.[13] There could be a racial difference in incidence or may be odontoma was the most common OT in those populations.

OTs showed a slight male predilection (ratio) in this study and is similar to studies from India,[5] Australia,[20] China.[1015] Male-to-female ratio of 1:1 was shown by ameloblastoma. This is similar from studies in India,[5] Nigeria[17] and China.[10] However, female predilection was shown from a Brazilian study.[9] KCOT also showed a predilection for males which is in concordance with many other studies[1021] but is not similar to a Brazilian study.[9] The difference is possibly disclosed among different populations.

The jaw most commonly affected was mandible with maxilla to mandible ratio of 1:6. This is in concordance with studies from Asia[1016] and Africa.[17] However, the predilection for both the jaws was shown to be equal from the studies of the American continent.[131822] The reason could be the lower frequency of ameloblastoma in that particular population.

In this study, different variants of ameloblastoma and calcifying epithelial OT (CEOT) were found. Ameloblastoma like tissue with unusual formation of dentinoid material was diagnosed in one of the cases. Dentinoameloblastoma (DA) is an unusual OT characterized by classic ameloblast like areas with unusual formation of dentinoid by neoplastic epithelial cells of odontogenic origin. The World Health Organization first defined the term DA in 1970.[23]

The variant of CEOT with clear cells was diagnosed in one of the cases. The first case of CEOT was described by Abrams and Howell in 1967 predominantly composed of clear cells.[24] Krolls and Pindborg considered two of those 23 cases of CEOT as a challenge in diagnosis due to predominance of clear cells. Since then, the clear-cell component in CEOTs has been reported mainly through single cases and its prognostic importance is still debatable.[2425262728293031]

CONCLUSION

OTs are rare group of lesions in the population studied and are represented mainly by the Ameloblastoma, KCOT, AOT and O. The clinical and histopathologic features of these neoplasms differentiates it from other oral lesions. OTs exhibits a male preponderance, and most cases are diagnosed in the 1st–3rd decades of life. Possible geographic variation of OTs was observed from the cases reviewed.

Financial support and sponsorship

Nil.

Conflicts for interest

There are no conflicts for interest.