Background: Ameloblastoma are benign but locally invasive neoplasms that represent 10% of all odontogenic tumors. Despite its benign characteristics, ameloblastoma has a high recurrence rate after treatment with a recurrence rate of 55-90%. It is important to identify the risk factors of recurrence to improve patient’s quality of life in oral and maxillofacial surgery. Methods: Patients who underwent surgery at the Department of Oral and Maxillofacial Surgery at Pusan National University Dental Hospital for 5 years from 2017-2021 and were diagnosed with ameloblastoma as a result of postoperative histological examination were included. The patients were divided into two groups, recurrent and non-recurrent, and comparative analysis was performed according to various factors. Results: First, when the lesion was involved with the inferior alveolar nerve (IAN), recurrence was more likely than when it was not. Next, recurrence occurs more often when cortical bone perforation is observed than when it is not. In particular, when resorption is shown on the lingual cortical bone, a remarkable tendency of recurrence is shown. Moreover, in radiographic characteristics, the multicystic type showed a higher recurrence tendency than the unicystic type. Conclusion: When the lesion is multicystic, perforating the cortical bone, infiltrating the adjacent soft tissue, or involving the IAN, a high recurrence rate is shown. The results of this retrospective analysis of the recurrence trend of ameloblastoma over a 5 years period are to contribute significantly to insight and reduction of recurrence rates in treatment for polymorphic lesion in oral and maxillofacial area.

It is well documented that giant cells can be observed in some types of odontogenic tumors such as central odontogenic tumor and dentinogenic ghost cell tumor. However, the presence of stromal giant cells has only rarely been reported in ameloblastoma, although being the most common epithelial odontogenic tumor. In this study, we present a novel case of peripheral ameloblastoma associated with peripheral giant cell granuloma arising in the mandibular alveolar mucosa of a 65-year-old male patient. The possible pathogenesis of this combined lesion will be discussed, in addition to the review of previous reports of ameloblastoma accompanied by stromal giant cells.

Dentigerous cyst is considered one of the representative cystic lesions, which accounts for approximately 15%-30% of the odontogenic cysts. Although its recurrence rate is low, a small proportion of dentigerous cysts converted into ameloblastomas, squamous cell carcinomas, and mucoepidermoid carcinomas. Here we present an uncommon case characterized by histopathological transformation from a dentigerous cyst to an ameloblastoma, and further investigate the factors contributing to its conversion.

Mucormycosis is an aggressive opportunistic fungal infection that can be found in the oral cavity. The fungus usually affects the immunocompromised patients and tends to invade and block blood vessels, resulting in significant tissue necrosis and invasive mucormycosis. However, a non-invasive form of mucormycosis is mostly asymptomatic and found accidentally in the immunocompetent normal hosts, manifested by localized overgrowth of the fungus. Here, we report a rare case of asymptomatic non-invasive mucormycosis of the mandible that was incidentally diagnosed in wide resection specimen of liver transplant patient who had previously underwent surgery of excision and simultaneous alloplastic bone graft due to mandibular ameloblastoma. Histopathological examination of the specimen revealed that there was neither vasculitis nor tissue necrosis, but numerous fungal hyphae were located only within the alloplastic graft materials in decalcified tissue sections. Awareness of the possibility of life-threatening mucormycosis in immunocompromised patients should be emphasized because it can be inactive or reactivated depending on the immune state of patients.

Ameloblastoma is an odontogenic tumor characterized by various sites of metastasis, malignant transformation, and a high recurrence rate over time. Ameloblastic carcinoma(AC) is the term reserved for an ameloblastoma with histologic evidence of malignancy in the primary tumor. AC is classified into two types: most ACs occur de novo, and only few cases of malignant transformation of ameloblastoma become apparent. Here, we report a case of AC, arising from recurrent acanthomatous ameloblastoma on the maxillary sinus, in a 60-year-old male patient. The mass was first diagnosed as acanthomatous ameloblastoma; subsequently, surgical curettage was performed thrice while partial maxillectomy was performed twice. On the fifth recurrence, the tumor was identified as AC.

Ameloblastoma is a benign odontogenic tumour of epithelial origin and comprises 1% of maxillomandibular tumors or cysts. The incidence of pathological changes such as ameloblastoma from the follicle of impacted third molar was reported to have low incidence. However, there are many reports that asymptomatic third molars are related with various pathological conditions. A case of ameloblastoma secondary to third molar extraction and subsequent sagittal split ramus osteotomy (SSRO) had not been reported. At the right ramus area, radiolucent lesion had been noted at 6 years after the surgical extraction of the third molar followed by SSRO for the mandibular prognathism. The lesion was proved to be the basal cell type ameloblastoma. There had been no significant bony lesion before or 1 year after the SSRO. The tumour was successfully removed and there was no evident recurrence at 4 year of the follow up after the removal of the ameloblastoma. There are some reports suggesting the pathologic potential of the pericoronal tissues of impacted third molars to develop odontogenic keratocysts and ameloblastomas. The current case reports a rare possibility of ameloblastic change at the site of uneventful healing after third molar extraction and orthognathic surgery.

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.

Peripheral ameloblastoma, a rare and unusual variant of odontogenic tumor, representing 1% of all ameloblastomas. The extraosseous location is the peculiar feature of this type of tumor, which is otherwise similar to the classical ameloblastoma. This paper describes a case of peripheral ameloblastoma in a 43-year-old female affecting the left retromolar pad area of the mandible which was clinically diagnosed as a pyogenic granuloma. Histologically, the tumor showed of follicular ameloblastoma in continuity with a surface oral epithelium.

Desmoplastic ameloblastoma (DA) and Ameloblastic fibroma (AF) show common histopathologic features such as enamel organ like epithelial islands or cords on the background of abundant fibrous stroma. Despite their similar histopathologic features, it was reported that they have different pathogenesis and clinical behavior. The purpose of this study was to rev iew clinicopathologic features of DA and AF among Korean subjects. 7 cases of DA and 4 cases of AF were retrieved from the files of Seoul National University Dental Hospital (SNUDH), and their clinical features, radiographic findings, and histopathologic features were reviewed and compared. DA occurred in 3 males and 4 females. They occurred from 24 to 62 years of age, showing the mean age of 42.7 years. 5 of the 7 tumors occurred in the maxilla, and all of them in the anterior region, showing predilection for the maxillary anterior regions. There was no recurrence. Radiographically, they showed well demarcated unilocular or multilocular radiolucency. AF occurred in 5 males and 2 female. They occurred from 6 to 29 years of age, showing the mean age of 14 years. All tumors occurred in the mandibular molar area. Recurrence was recognized in 1 case. Although DA and AF showed similar histopathologic features, they showed different clinical behaviors. While DA showed predilection for the anterior maxilla, AF did for posterior mandible. While DA occurred mainly in adults, AF did in adolescents. Recurrence was recognized not in DA but in AF. Therefore, DA and AF should be differentiated from each other in spite of similar histopathologic findings

Desmoplastic ameloblastoma(DA) is histologically characterized by extensive stromal collagenization or desmoplasia. ln this study, anti-cytokeratin 8/18, 13, 19 for pathogenesis as well as anti-PCNA for cellular proliferation, were used to det ect the expression of these proteins in the desmoplastic ameloblastoma Basal layers of tumor nest were negatively stained by CKl3, while suprabasal and inner cells were positive for CK13. CK8/18 and CK 19 was negatively stained in the peripheral portion of tumor nest in DA, whereas CK 8/18 was in central portion and CKl9 was positive in the su prabasal and some of central portion of the cel l nest. PCNA index of DA was 60 ::!: 14.6% to 95 ::!: 17 .2%. The peripheral tumor cells of the islets presented higher PCNA labeling index, while some cells in the central area of foll icle containing squamous like cells also presented negative PCNA labeling index. Especially tumor islands showed higher PCNA index than in main tumor mass. lt suggested that desmoplastic ameloblastoma might be composed of many different tumor cell types‘ and have hi gher pr이 ife r a ting activity in tumor islands of the desmoplastic stroma

Ameloblastic carcinoma is an ameloblastoma wi th histological malignant transformation with 01' without metastatic di sease_ We report an ameloblastic carcinoma ex ameloblastoma of right mandibular body in 7 -year-old girl with a heterogeneo us hi stologic components_ The tumor s howed so lid s heets composed of atypical kerati nized squamous cells. small ovoid cell s. and s pind le cells in addi tion to a bit of beni gn ameloblastoma component_ Immunohis tochemically, the squ amous cells were strongly cytokemtin posi ti ve/vimentin negati ve and the small ovoid and spindle ce lls were weakJy cytokeratin positi ve/v imentin pos it ive_

In order to perform the protein analysis using the paraffin sections previous fixed with formalin, we applied the ImmunoMemBlot (IMB) method1) to detect the epitopes of target proteins with specific antibodies. In this study the protein extracts were obtained from the paraffin sections of each representative case of ameloblastoma, adenomatoid odontogenic tumor (AOT), and normal gingiva, and more a protein extract from fresh tissue of ameloblastoma was also compared to evaluate the IMB results used with 24 different antibodies. First of all, in the comparison between the paraffin section extract and fresh tissue extract of ameloblastoma, the latter consistently showed more positive IMB reaction than the former. Meanwhile, the paraffin section extract of ameloblastoma was more comparable with that of normal gingival, disclosing that most of proliferating genes, oncogenes, and apoptosis related genes, i.e., PCNA, CDK4, c-erbB2, CEA, p53, Bax, Bad, FLIP, FAS, Bcl-2, p21, N-ras, MMP-2, MMP-9, caspase-3, -8, -9, were highly expressed in ameloblastoma, but EGFR, HGF, and VEGF were similarly expressed both in the ameloblastoma and in normal human gingiva. On the other hand, the comparison between ameloblastoma and AOT both in the immunohistochemistry and IMB using their paraffin section extracts clearly demonstrated that the ameloblastoma showed more expression of proliferating genes and oncogenes while the AOT showed more expression of apoptosis related genes, i.e., Bax, Bad, FLIP, and caspase-9. Taken together, these data suggest that the IMB can be used for the primary screening of quantitative protein analysis using the paraffin section extract, and that the IMB results could be evaluated in conjunction with the immunohistochemical observation.

The purpose of this study was to evaluate the role of Fas, Fas-L, and FAP-1 expression in the oral squamous cell carcinomas and ameloblastomas. For this study, 10 subjects diagnosed as squamous cell carcinoma and 8 subjects of ameloblastoma referred to the Dept. of Oral Pathology, School of Dentistry, Kyung Hee University, 5 subjects of normal oral mucosa without any inflammatory changes were used as experimental, control groups respectively. All the tissues ; experimental and control group were fixed in neutral formalin solution and embedded in paraffin, serial tissue section were made 5㎛ in thickness and processed in the standard way for immunohistochemical method, using primary antibody against Fas, Fas-L, FAP-1, each was diluted at 1;100 followed by the super sensitive non- biotin horse radish peroxidase detection system with DAB as chormogen, counterstained with Gill's hematoxylin stain method , mounted. And examined under the biologic microscope with the criteria of -(no epithelial stain), +(weak or focal epithelial stain), ++(moderate or focal intensive epithelial stain), +++(intense generalized epithelial staining) for the epithelial, and connective tissue component in squamous cell carcinomas , ameloblastomas and normal oral mucosa on each. In normal oral epithelium, negative reaction was noted on the Fas . Fas-L stain, but on FAP-1 reaction, tumors cells with intense reaction on nuclei and cytoplasm or negative reaction on nuclei with intense reaction on cytoplasm were admixed. On Fas, Fas-1 reaction, both tumor cells of ameloblastoma and oral squamous cell carcinoma showed negative reaction on nuclei and cytoplasms. On FAP-1 reaction, tumor cells of oral squamous cell carcinomas showed more intensive response compare to that on ameloblastomas. Considering these results, the tumor cells of ameloblastoma and squamous cell carcinoma showed negative reaction on the Fas and Fas-L, but it could suggest that FAP-1 induce the development of tumors by means of inhibition of the apoptosis.

Ameloblastoma and adenomatoid odontogenic tumor showed quite different tumorigenesis and prognosis , Besides theil‘ growth potential and histological features , there must be an essential diffcJ'cncc in gene expJ'ession profile between ameloblatoma and adenomatoid odontogenic tumor , The gene expression profiles we1'e compared by im munohi stochemi stry and immunoblot methods using different monoclonal and monospecific antibodies against on cogenes, growth factors, signaling molecules‘ matrix proteins, enzymes, Based on the immunohi stochemical find ings previously J'epo1'ted in the literature we found some di stinguishing feature of gene expressions 1'0 1' the tu mOl'igenesis between ameloblastoma and adenomatoid odontogenic tumors , The hi s togeneti c and mol eculal' mechani sms of both tumors wiII be discussed

It is very little known that the molecular mechanisms control growth, cell differentiation, and invasion of ameloblastoma into bone. Tissue culture methods have also been used extensively for studies of the cell biology of ameloblastoma. The purpose of this study were to examined the ultrastructural features of ameloblastoma, and to apply these results to examine the pathogenesis of ameloblastoma in the future. Amelobalstoma was primarily cultured under 0.1, 0.15 and 1.2mM Ca++ of KBM bullet kit at 370C and 5% C02. For transmission electronmicroscopy(TEM), cultured ameloblastoma cells were immediately fixed in 2.0% glutaraldehyde in O.lM cacodylate buffer(pH 7.4) at 40C for 1h The ultrathin sections were stained with uranyl acetate and lead citrate, and examined by TEM. The obtained results were as follows. Primay culture ameloblastoma grown in 0.1 mM Ca++ showed interlacing papillary projections without desmosome within early passage(3-4). Primary culture amelobalstoma under high calcium showed prominent desmosomes or tight junctions within early passage. There was evidence of cellular degeneration, as exemplified by nuclear pyknosis, the margination and clumping of the chromatin, and vaculolation under high calcium. The sparse ribosomes, the cytoplasmic space filled with vacuoles, and the condensed mitochondria were seen under high calcium. From the aboving results, under high calcium primary culture ameloblastoma showed rapid cellular degeneration within early passage, indicating that the cells were gradually losing metabolíc actívitíes, leading to enventual cell death. It was thought that it would be necessary to establish cultured immortalized amelobalstoma cell line for studying the pathogenesis of odontogenic tumors.