Odontogenic keratocyst (OKC), also known as keratocystic odontogenic tumor, is a distinct clinicopathologic lesion that can be clearly identified by histologic examination. Clinically, OKC is characterized by a high recurrence rate. This report describes a rare case of OKC with mural calcification in the maxilla of a 47-year-old male patient. Orthopantomography and Cone Beam Computed Tomography showed full opacification with calcification and lateral wall resorption in the left maxillary sinus, destroying the sinus floor. Hard tissue deposits have rarely been reported in the connective tissue walls of OKC. The importance of calcified material formation to the biological behavior of OKCs is unclear. Although its prognostic value has not been studied, the presence of calcification materials does not appear to increase the risk of recurrence. Study of a number of samples would be needed to determine the nature of the correlation between the presence of calcified materials and recurrence.

Odontogenic keratocyst (OKC) is aggressive compared to other odontogenic cysts, but its malignant transformation is extremely rare. Odontogenic carcinoma may arise from an odontogenic cyst such as OKC. Here in, we introduce a case of odontogenic carcinoma assumed to have arisen from a preexisting OKC. Abnormal clinical and radiologic features seen in a previous or existing cyst may be warning signs of malignant transformation.

Odontogenic keratocyst (OKC), also known as keratocystic odontogenic tumor (KCOT), is an emerging odontogenic tumor originating from the dental lamina. It is an aggressive lesion with a squamous epithelium and a recurrence rate of 15-35%.1 Radiologically, there is a clear, smooth, or shell-like border showing a unilocular or multifocal, polycystic radiographic picture. Hard tissue formation in OKC is a very rare phenomenon and occurs in the form of dystrophic calcification, cartilaginous tissue or dentinoid.2 In this article, we report the case of OKC with calcification. OKC with radiopaque lesion is very rare, these are considered as dystrophic calcification, dentinoid formation, ossification. The incidence of dystrophic calcification in recurrent OKC is low, so it can be inferred that the recurrence rate of OKC with dystrophic calcification is lower than that of conventional OKC.

Odontogenic cyst and odontogenic tumor shares developmental source. However, they have different histopathologic features, and they are classified respectively. Odontogenic cyst and tumor can share same physical region. It is called a hybrid lesion, a lesion showing the combined histopathological characteristics of two or more previously recognized odontogenic tumor and/or cysts of different categories. In this study, a hybrid lesion was researched. 61-year old man was referred to our department with a multilocular radiolucency in right mandibular angle. Incisional biopsy was carried out, and the patient was diagnosed with ameloblastoma. Odontogenic keratocyst was found with the tumor, and it was thought to be evolved via neoplastic transformation from lining epithelium of the keratocyst. After reviewing studies reporting hybrid lesions from odontogenic cyst and tumor, formation of a hybrid lesion was most frequent from a dentigerous cyst and an adenomatoid odontogenic tumor. A hybrid lesion commonly lead to misdiagnosis, and the prognosis is not always transparent. The close relationship between the odontogenic cyst and tumor has to be kept in mind in the diagnosis and treatment of the lesions in maxillofacial area.

Angiogenesis is a process with a coordinated sequence of endothelial cell division, selective degradation of vascular basement membranes, and surrounding extracellular matrix with migration of theses cells that result in a new capillary growth from preexisting vessels. These processes are controlled by numerous different molecules. Among these, Vascular Endothelial Growth Factor(VEGF) is an endothelial cell-specific mitogen with a potent ability to induce microvessel permeability and angiogenesis. In this study, tissue samples of odontogenic keratocyst(10 cases), ameloblastoma(10 cases), adenomatoid odontogenic tumor(10 cases), calcifying epithelial odontogenic tumor(10 cases), ameloblastic carcinoma(2 cases) were obtained, and all specimen were routinely fixed in 10% formalin and embedded. Serial 5μm thick sections were cut from paraffin blocks. And the immunohistochemical staining, characteristics of VEGF about the cyst & tumor were observed & obtaned the results from this study. We presume that the growth of cyst is depends on not a differentiation but an epithelium & connective tissue. But, in odontogenic tumor, we presumed that the growth of tumor is influenced on inflammation & surrounding stimulus & vascular growth and supply. Therefore, it should be suggested that study on the growth of tumor and vascularity must be carrying out in this immunohistochemical study.

A case was reponed in which an odontogenic cyst that appeared to be a dentigerous cyst associated with an impacted mandibular third molar was found histologically to demonstrate characteIistics of glanclu lar odontogenic cyst with para- and orthokeratinization. 까1ese histologic cliversities were interpreted as a reflection of the pluripotentiality of the epithelial remnants of the mandibular thircl molars or clentigerous cyst epithelium. It was conceivable that it would have the capacity of inclucing the fonnation of cysts with both squamous and glandular epithelium.

Odontogenic keratocysts(OKCs) are frequently associated with erupted or impacted tooth. In such instances, the radiographic features simulate those of a dentigerous cyst. The purpose of this study was to evaluate a comparative immunohistochemical expression of Ki-67 as a proliferative marker and apoptotic signals in the OKC associated with or without impacted tooth. In addition, we have also been investigated with regard to the proliferative activity and apoptosis comparing the unilocular and multilocular varieties of the OKC. The material for this study consisted of thirty-two cases of OKCs (OKC with impacted tooth, n=16；OKC without impacted tooth, n=16) and ten cases of dentigerous cysts as a comparison. The results revealed that the proliferative activity and apoptosis of OKCs with impacted tooth was higher than those of dentigerous cysts. However, there was no correlation between Ki-67 immunoreactivity or apoptosis and association with or without impacted tooth in 32 cases of OKCs. In addition, this present study showed that there was no correlation between the unilocular and multilocular varieties of the OKCs in proliferative activity and apoptosis.