|Year : 2023 | Volume
| Issue : 5 | Page : 64-68
Orthokeratinised odontogenic cyst: A case series
Rashmi Metgud, Anukriti, Smitha Naik, Aniruddh Tak
Department of Oral Pathology and Microbiology, Pacific Dental College and Hospital, Debari, Udaipur, Rajashtan, India
|Date of Submission||16-Dec-2021|
|Date of Decision||19-Oct-2022|
|Date of Acceptance||04-Jan-2023|
|Date of Web Publication||04-Feb-2023|
Pacific Dental College and Hospital Debari, Udaipur, Rajashtan
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Orthokeratinised odontogenic cyst (OOC) is a distinct and an uncommon odontogenic cyst of jaw. It was previously considered as orthokeratinized variant of Odontogenic Keratocyst, owing to its same site, age and occurrence and origin. In 2017 WHO classified OOC under odontogenic cysts as a distinct entity, clearly separating it from Odontogenic Keratocyst (OKC). In cases of malignant transformation, the cyst shows unclear boundaries. The cases that reported to the department during the period 2019-2021 were retrieved and then reviewed by the authors. A total of 7 cases that met the histopathological criteria for OOC were included in the study. There was a clear male predilection. Age of patients ranged between 17 to 65 years. Most of cases showed Unilocular radiolucency but one case revealed Multilocular pattern. Grossly specimens ranged between 0.5 cm to 3.0cms. Histopathological findings showed all classic features of OOC. FNAC was also done and it is clearly evident that the use of Cytology can help us diagnose the cyst early and is a less invasive method. OOC is a rare type of odontogenic cyst, but while making the diagnosis one should not forget about the fact that it is less aggressive and needs to be differentiated from OKC. Majority times it has been seen that Clinico-radiographic diagnosis given of any circumscribed radiolucency around an impacted tooth is Dentigerous cyst, which is not correct. Diagnosing such lesions require thorough histopathological and radiographical correlation along with molecular analysis to reach final diagnosis.
Keywords: Keratinised cyst, odontogenic cyst, Developmental, orthokeratinisation
|How to cite this article:|
Metgud R, Anukriti, Naik S, Tak A. Orthokeratinised odontogenic cyst: A case series. J Oral Maxillofac Pathol 2023;27, Suppl S1:64-8
|How to cite this URL:|
Metgud R, Anukriti, Naik S, Tak A. Orthokeratinised odontogenic cyst: A case series. J Oral Maxillofac Pathol [serial online] 2023 [cited 2023 Mar 21];27, Suppl S1:64-8. Available from: https://www.jomfp.in/text.asp?2023/27/5/64/369183
| Introduction|| |
Orthokeratinised Odontogenic Cyst (OOC) is a distinct intraosseous cyst of the jaw, accounting for almost 7%–17% of all keratinising jaw cysts. In 1981, Wright described the orthokeratinised variant of odontogenic keratocyst. It was not before 1998 when Li et al. coined the term 'Orthokeratinized Odontogenic Cyst'. However, in 2017 the WHO reclassified OOC under odontogenic cysts as a distinct entity, clearly separating it from Odontogenic keratocyst (OKC).
Male predilection of the cyst has been noted, with the mandible being almost twice as involved as the maxilla. Association of OOC with the impacted tooth is the major cause of getting it misdiagnosed as dentigerous cyst. Although it presents as a unilocular lesion with a well-defined boundary, multilocular cases of OOC have also been reported.
Additionally, cases have been seen of unclear boundaries of the cyst in case of its malignant transformation. OOC differs from OKC not only due to its epithelial lining but also due to its proliferating kinetics, clinical, immunohistochemical, and biological behaviours. OKC shows more aggressive behaviour (28%–30%) compared to OOC and has been associated with nevoid basal cell carcinoma syndrome. The treatment of choice is enucleation with curettage as it shows only a 2% recurrence rate.
| Materials and Methods|| |
In the department of oral and maxillofacial pathology, archived cases referred from different departments were reviewed. Cases that presented with an uninflamed fibrous wall lined by thin, regular stratified, completely orthokeratinised and non-corrugated squamous epithelium with a thick lamellated keratin layer extending into the lumen and with a granular layer extending throughout the epithelial length suggestive of OOCs were included in the study. In the time span of two years, from 2019 to 2021, a total of seven cases were reported in the department.
| Results|| |
Clinical and Demographic Findings
There were a total of seven cases out of which four (58%) were male patients and three (42%) were female patients. The patients age ranged between 17 to 65 years with a mean age of 34 years and median age of 36 years, respectively (refer [Table 1] for gender wise age involvement). Out of the seven reported cases, four (58%) involved the mandible and three involved the maxilla. Also, posterior mandible involvement was found to be the highest, that is, in four cases (58%) and anterior mandible involvement was found to be the least, that is, zero out of seven cases. On the other hand, posterior maxillary involvement was found in only one case (14%) and anterior maxillary involvement was found in two cases (28%).
Radiographically, one out of the seven cases (14%) showed a multi-locular lesion and the remaining six cases (86%) revealed a well-demarcated unilocular radiolucency. We found that all the seven cases were associated with an impacted tooth: five cases were associated with impacted third molars, one case was associated with impacted canine, and one case with impacted mesiodens. To our surprise while majority showed a well demarcated unilocular radiolucency, one case showed irregular multilocular radiolucency. The case wise radiological features are listed in [Table 2].
There was one recent case (s.no. 7 in [Table 4]) in which fine needle aspiration cytology (FNAC) was performed [ref. [Figure 1]. The Pap-stained smears revealed the presence of abundant anucleated keratin squames admixed with few inflammatory cells [ref. [Figure 2] such as lymphocytes and fibrinous material suggestive of OOC.
Excisional biopsy was performed in five cases and incisional biopsy was done in the remaining two. Multiple pieces of cyst tissues were received, all ranging in sizes between 0.5 and 3 cm. All the pieces were irregularly flattened and soft to firm in consistency. They were all pearl white to brown in colour. Comparison of all the cases are tabulated in [Table 3].
Histopathologically in all seven cases, scanner view revealed a bit of tissue with cystic lumen lined by an epithelium and connective tissue stroma [ref. [Figure 3]. Low-power view revealed that cystic lumen was lined by orthokeratinised stratified epithelium of uniform thickness with prominent granular layer and connective tissue stroma. Stroma was composed of collagen fibres interspersed with fibroblasts, numerous endothelial lined vascular spaces RBCs, and chronic inflammatory infiltrate [ref. [Figure 4]. High-power view confirmed the above-mentioned findings with chronic inflammatory infiltrate chiefly composed of lymphocytes [ref. [Figure 5]a and [Figure 5]b.
|Figure 3: A cystic lesion with epithelial linning and fibrous connective tissue capsule (H & E)|
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|Figure 4: The epithelium revealed uniform orthokeratinised stratified squamous epithelium with a prominent granular cell layer|
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|Figure 5: Fibrous capsule revealed dense collagen bundles and few chronic inflammatory cells|
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| Discussion|| |
Orthokeratinised odontogenic cyst (OOC), an uncommon odontogenic cyst accounting for only 11% of odontogenic cysts, has a very low rate of recurrence. Some of the previously diagnosed OKC now clearly show properties of OOC, making its incidence ranging from 5.2% to 16.8%. the studies by Gillette and Weinmann reported that OOC was often misdiagnosed as a dentigerous cyst with keratinization, in which the latter was similar to OKC.
In the past few years, various authors have reported many cases of orthokeratinised odontogenic cyst. Li et al., Dong et al., Selvamani et al., and Uddin et al. reported the male-to-female ratio to be above or equal to 2:1 (refer [Table 5] for detailed comparison). However, in our study, there were three female patients out of seven, converting the ratio to 1.3:1, which was almost similar to the findings of Vera-Sirera et al. in 2016. Except in the findings of Mahdavi et al., all studies, including ours, were suggestive of more mandibular involvement, while the former was suggestive of equal involvement of both the mandible and maxilla. A varying percentage of involvement can be observed of the impacted tooth in the studies from 30%–85.8%. Our study is suggestive of more involvement of the impacted tooth as compared to the study by Uddin N et al., which was suggestive of only 30% involvement.
Da Silva et al., in 2002, performed an immunohistochemical study on 12 cases of both OOC and OKC for comparison. They found out that OOC expressed Cytokeratin-10 (CK-10) more consistently while also expressing CK-13 and CK-14, but the latter were variable. In OKCs, CK-10 was expressed in superficial keratin while CK-14 was expressed variably in the basal and suprabasal layers. In OKC, fibronectin and collagen type I and III were expressed in non-fibrillar pattern, whereas in OOC it showed a fibrillar arrangement. This was suggestive of OKC being more aggressive, thereby supporting the fact that OOC is less aggressive and shows very less tendency of recurrence. Conservative enucleation and periodic follow up can lead to 'no recurrence' as well.
| Conclusion|| |
OOC is a rare type of odontogenic cyst. While making the diagnosis one should not forget about the fact that it is less aggressive and needs to be differentiated from OKC. Furthermore, because of its more involvement with the impacted tooth we need to differentiate it from the dentigerous cysts as well. It is clearly evident that the use of cytology can help us diagnose the cyst early and is a less invasive method.
We thank staff members from the department of Oral medicine & radiology and Oral & maxillofacial Surgery for referring the cases for histopathological evaluation.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]