Background and Objective: Odontogenic keratocyst is a developmental Odontogenic cyst. It is to be considered for histopathological features and clinical behavior. It has aggressive behavior and tendency to recurrence and it has been named benign cystic neoplasm. OKCs have different radiographic appearance such as unilocular to multilocular radiolucency. In some cases, they have been observed in the interradicular area but in rare cases they can be found in periapical radiolucency in apex of non-vital teeth that may be mistaken with lesions of endodontic origin and cause mistreatment.Case Report: A 33 year old male patient came to clinic because of swelling in the anterior region of mandible that was repaired with endodontic treatment. In the histological diagnosis of radiolucent lesion, inflamed Odontogenic keratocyst was reported.Conclusion: Diagnosis based on clinical finding may risky because it can lead to inappropriate treatment. In most of the cases, microscopic examination of all material surgically removed is necessary for diagnosis. This is especially recommended when treatment of lesion is not successful with routine treatment.

Background and Aim: Odontogenic keratocyst is a developmental Odontogenic cyst with aggressive behavior and tendency to high recurrence. The cyst’s epithelium shows more potential for growth than follicular cyst. On the other hand, BCL-2 is an anti apoptotic protein that can increase the longevity of epithelial cells. The purpose of this investigation was to compare the immunoreactivity in different layers and linings of both epitheliums of the follicular cyst and Odontogenic keratacyst using BCL-2 anti-apoptotic marker.Materials and Methods: A retrospective descriptive study design was employed in order to evaluate 20 paraffin blacks of Odontogenic keratocyst and 20 paraffin blocks of follicular cyst. The immunohistochemistry staining method was used together with BCL-2 marker (Anti BCL-2, Clone 124, Isotype: IgG, Kappa, Dako, Denmark).The cytoplasms of epithelial cells were immunostained in different layers and all linings of the epithelium for both cysts, in 1000 epithelial cell counts. The collected data was analyzed using SPSS statistical software, and Roc Curve analysis as well as student T-test in order to prepare and report the results.Results: Immunoreactivity with BCL-2 marker was 98.5 (±1.4%) in Basal layer, 12.1 (±3.2%) in intermediate, and null (0) in the surface layer of Odontogenic keratocyst. Immunoreactivity with BCL-2 marker in basal layer was 2.1 (±1.9%) but the surface and intermediate layers did not immunostained with BCL-2 marker. The mean number of epithelial cells, positive for BCL-2, in all linings of follicular cyst was 0.7 (±0.63%) and in Odontogenic keratocyst was 36.8 (±1.5%). The mean immunoreactivity difference in layers of Odontogenic keratocyst was statistically significant (P<0.05) in different layers of follicular cysts.Conclusion: Based on the results of this study, BCL-2 seams to be involved in pathogenesis of the Odontogenic keratocyst. Likewise, the over-expression of BCL-2 marker in basal layer of Odontogenic keratocyst was associated with increased recurrence and aggressive behavior of Odontogenic keratocyst when compared with follicular cyst. Therefor, it can be suggested that the overexpression of BCL-2 in basal layer of Odontogenic keratocyst can be considered as a useful marker to differentiate it from follicular cyst.

Background and Aim: Ameloblastoma (AM) and Odontogenic keratocyst (OKC) are common lesions with a high recurrence rate. Epidermal growth factor receptor (EGFR) regulates cell proliferation and survival. Considering the controversial results of previous studies regarding the expression of EGFR in Odontogenic cysts, this study aimed to compare the expression of EGFR in AM and OKC.   Materials and Methods: In this descriptive study, 49 specimens (20 AM and 26 OKC) were evaluated. Five micrometer sections were made for immunohistochemical staining. Immunohistochemical analysis was performed using super-sensitive one-step polymer-HRP. Expression of EGFR was first assessed quantitatively by measuring the count of membrane- and/or cytoplasm-stained epithelial cells in AM  (ameloblastoma-like cells, stellate reticulum, and all epithelial cell layers) and OKC (basal layer, suprabasal and basal layers, and all epithelial cell layers). Next, each specimen's mean percentage of stained cells was scored and classified into four groups (less than 5%, 5-25%, 25-50%, and more than 50% stained cells). Data were analyzed by t-test and Mann-Whitney test to compare the mean EGFR expression and the percentage of stained cells. The Chi-square test was used to compare the location of EGFR expression. Results: The mean percentage of EGFR expression was 81.39±10.41% in AM and 78.05±19.27% in OKC. The results showed no significant difference between AM and OKC regarding EGFR expression, EGFR score (P=0.141), or EGFR expression in different layers (P=0.303). Conclusion: EGFR expression showed no significant difference between AM and OKC.

The Odontogenic keratocyst (OKC) today is called keratocystic Odontogenic Tumor (KCOT) by the WHO, consider as a benign intraosseous developmental Odontogenic tumor and may be presented in unicystic or multicystic variants. The tumor is surrounded by stratified squamous parakeratinized or orthokeratinized epithelium and has invasive or infiltrative behavior. It happens in the second and third decades of life, and often is more prevalent among males. In this case report we describes an unusual case of OKC in the condylar region and its infiltration into parotid gland which is very rare and minimal clinical presentation indicative of a tumor.