| Abstract|| |
Background: Ameloblastoma is a benign slow growing tumor of odontogenic origin composed of epithelial cells that resemble enamel forming cells namely the ameloblasts however these lesional cells do not differentiate to produce enamel. They are locally aggressive and can cause severe abnormalities of the face and jaw. Aim: This study aimed to correlate the incidence and recurrence rates of ameloblastoma to the different clinical and histopathological parameters. Methods: A study on ameloblastomas in the Goan population for 16 years (1999–2014) was carried out. Archived documented data of surgically treated cases of ameloblastomas were used in this study. Results: It was revealed that out of 52 cases of ameloblastomas, a male preponderance was seen. Age predisposition was seen to favor the third-fourth decade, the most common site was the posterior aspect of lower jaw for new and recurrent cases. Conclusion: The study highlights, the possible etiological role of location influencing the incidence and recurrence rates of ameloblastomas.
Keywords: Ameloblastoma, odontogenic tumors, recurrence
|How to cite this article:|
Carvalho KM, Dhupar A, Spadigam A, Syed S. Ameloblastoma: A 16-year clinicopathological study on Goan population. Indian J Pathol Microbiol 2017;60:157-60
|How to cite this URL:|
Carvalho KM, Dhupar A, Spadigam A, Syed S. Ameloblastoma: A 16-year clinicopathological study on Goan population. Indian J Pathol Microbiol [serial online] 2017 [cited 2017 Jun 26];60:157-60. Available from: http://www.ijpmonline.org/text.asp?2017/60/2/157/208374
| Introduction|| |
The tooth-forming apparatus is heterogeneous in origin, i.e., it is derived from epithelial or ectomesenchymal tissues or both. Odontogenic tumors are incompletely formed derivatives of this complex organ and comprise 1% of all oral and maxillofacial biopsy specimens diagnosed. According to the World Health Organization (WHO 2005), the ameloblastoma is a benign odontogenic tumor solely derived from an odontogenic epithelial origin, and it alone accounts for around 23% of odontogenic tumors.
Cusak in 1827 first described this lesion in a case report of mandibulectomy. The term ameloblastoma was suggested by Ivy and Churchill later in 1960, based on its odontogenic origin. Studies have now confirmed that the epithelial cell of origin is the ameloblast cell by targeting the protein by-product of the cell which is amelogenin. Based on these studies, histologically similar and related tumors, namely, the adamantinoma of long bones and the craniopharyngioma are now considered unrelated.
This lesion causes massive expansion of the jaw bones involving both bony cortical plates, resulting in gross asymmetry of the face, occlusal derangement and at times cortical plate perforation and pain due to secondary infection. The treatment of choice follows a radical surgical approach encompassing wide resection procedures of the jaw such as marginal, segmental, and composite resections.,
Recurrence rates following such morbid surgical procedures have been estimated to be as high as 50% of all surgically treated cases. The reason for such a high rate of recurrence is multifactorial; therefore, it is imperative to evaluate every case for recurrence risk parameters before formulating a surgical treatment plan.
This study aimed to correlate the recurrence rates of benign ameloblastoma to the inherent nature of different clinicopathological subtypes, to highlight unique findings and a possible hypothesis for site predilection.
| Methods|| |
Retrospective clinicopathological data on a total of 52 diagnosed and treated cases of ameloblastoma were obtained from the Department of Oral and Maxillofacial Pathology, of a Government Dental Hospital in Goa. The study spanned a period of 16 years (i.e., 1999–2014). The variables of age, gender, anatomic location and histologic subtype were evaluated. Radiographic findings of all cases were excluded in this study.
Age was stratified into groups of 10-year intervals, with the first being 11–20 years. The site of occurrence was categorized into the following, anterior maxilla, anterior mandible, posterior maxilla, posterior mandible (right and left), and bilateral posterior mandible. Permutations of clinicopathological criteria with age, gender, and jaw site predilection were evaluated.
According to the WHO 2005 classification, the cases in this study of benign ameloblastoma fell into the following three categories: unicystic ameloblastoma (UA), solid/multicystic ameloblastoma (SMA), and desmoplastic ameloblastoma.
This was based on histopathological evaluation of tissue sections stained with hematoxylin and eosin stains. The solid variant was further subdivided into the follicular and plexiform variants. The cases which recurred after undergoing enucleation and curettage, segmental and en bloc resection procedures in the study time frame were further analyzed for the parameters of jaw site location at initial and at recurrent presentation, age, and histopathology.
| Results|| |
Peak incidence fell in the third and fourth decade. Mean age was found to be 30.5 years. No age predilection was seen with the desmoplastic variant. An overall female preponderance was recorded in this study. This was particularly reflected in the unicystic variant; however, an inverse was true in the case of the follicular variant of the SMA subtype.
Location in jaw bones favored the posterior aspect of the mandible for both unicystic (93.75%) and multicystic variants (82.76%). The anterior aspect of both upper and lower jaws was the most common site for the desmoplastic variant (80%) [Table 1]. Bilateral cases were seen to have a unicystic histopathology (31.25%).
Among the three clinicopathological variants, the solid/multicystic subtype predominated.
In the span of 16 years, five cases recurred (9.43%). Of the cases which showed recurrence, the solid/multicystic variant and more specifically the follicular subtype predominated (60% of all recurrences). The posterior mandible was the most preferred site at both primary and recurrent presentations in a time frame of 2 years (80% of all recurrences). It was observed that the male gender predominated among the recurred cases (60% of all recurrences) [Table 2].
|Table 2: Tabulation of recurrent cases based on clinicopathological parameters|
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Three of the five cases that recurred fell in the 25–35-year age group, independent of the histological subtype. UA and SMA cases as seen by this study showed an average of 6 and 5 years' time frame for recurrence, respectively.
| Discussion|| |
Most of the cases in this study fell in the third and fourth decades which were similar to the findings of Kim and Jang 2001, Hasegawa et al., 2013 and Shoor et al., 2014.,, In this study, the desmoplastic variant showed no age predilection.
The male to female ratio is 1:1.3, is in accordance with results of other similar studies. However, most Indian studies on ameloblastoma report a male preponderance or an equal gender distribution. Our study showed similar results only in case of the follicular variant of ameloblastoma.
The posterior quadrant of the lower jaw was the most favored site, which supports literature claims that 80% of all ameloblastomas are found in the mandible. The desmoplastic variant showed a typical anterior predisposition, for both upper and lower jaws. It is well known that clinico-radio-pathological features of this variant have warranted it to be categorized as a distinct subtype of ameloblastoma. Five bilateral cases of UA were recorded in this study. Similar isolated cases were reported by Ogunsalu et al. and Deshmukh et al. both of which showed unicystic histopathology.,
A pattern of predominance of solid/multicystic ameloblastoma over unicystic and desmoplastic variants of ameloblastoma have been established by some studies., Between the histopathopathological subtypes of SMA, the follicular variant (64.51%) predominated over the plexiform variant, which is an almost uniform finding in studies on ameloblastoma done globally., The inverse was found to be true, in cases of ameloblastoma seen in the adolescent age group.
Recurrence of SMA, particularly in the posterior aspect of jaw bones, is a common finding seen uniformly across the spectrum of studies done on ameloblastoma.,,, The predomination of the follicular pattern in recurrent cases was in accordance with findings of other studies., It is noteworthy that in this study, the younger age seen in the recurrent cases can be explained by racial and demographic findings as stated by a study done in Kenya which conclude a younger age of onset in developing nations.
The current norms of treatment of primary ameloblastoma are based both on histopathology and location. UA is treated by marginal resection of the jaw; however, enucleation along with Carnoy's fixative as a cauterizing agent is at times advocated for very young patients (i.e., the first decade of life). This radical treatment approach for UA is debated by several authors, and no consensus has been reached regarding the same, till date. For SMA, radical surgery with a 1.5–2.0 cm healthy bone margins is followed. For recurrent cases, irrespective of site or variant, the treatment follows one which is used in case of SMA with an annual clinical and radiographic follow-up for the first 5 years posttreatment.
The high incidence and recurrent rate in the posterior quadrant can be explained by the presence of active odontogenic rests in the third molar region by virtue of it being the last tooth to erupt in both upper and lower jaws. The odontogenic cells rests within a neural crest cell derived ectomesenchyme can get activated due to reciprocal induction by aberrantly activated Sonic hedgehog (Shh) and the Wingless (Wnt) pathways. The third molars are considered rudimentary organs. The latent ligands such as bone morphogenetic protein and transforming growth factor beta (TGF-β) can get activated either due to hindered eruptive forces or inflammation caused due to an impacted third molar.
To decrease the incidence of ameloblastoma, the elective extraction of asymptomatic impacted/partially impacted third molars is commonly advocated in developed nations. However, recent evidence shows that there is insufficient data to support a direct role of asymptomatic impacted third molar in the etiopathogenesis of ameloblastoma. Third molar extractions are also known to be associated with a high risk of iatrogenic complications.,
The goal, however, should be the monitoring and elimination of inflammation around a receptive and inductive ectomesenchyme located in the posterior quadrant of the jaw bones. This study hypothesizes the possible role of the inflammation (i.e., TGF-β) from adjacent second molar periodontium (i.e., periapical inflammation) and overlying gingiva (i.e., pericoronitis) of erupting the third molar to act as a stimulant to the persisting active odontogenic cell rests in posterior jaw quadrant.
Future research potential can be met by evaluating the role of known inflammatory markers on ectomesenchyme around asymptomatic impacted third molar.
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Conflicts of interest
There are no conflicts of interest.
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Karla Maria Carvalho
Liberty Apartments, Flat No: 202, Feira Alta, Mapusa - 403 507, Goa
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2]