Displaying publications 21 - 38 of 38 in total

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  1. Ng KH, Siar CH, Murugasu P
    Ann Dent, 1986;45(2):19-22.
    PMID: 3468872
    Matched MeSH terms: Odontogenic Tumors/epidemiology; Odontogenic Tumors/pathology*
  2. Siar CH, Kawakami T, Buery RR, Nakano K, Tomida M, Tsujigiwa H, et al.
    Eur J Med Res, 2011 Nov 10;16(11):501-6.
    PMID: 22027644
    Notch signaling is an evolutionarily conserved mechanism that enables adjacent cells to adopt different fates. Ghost cells (GCs) are anucleate cells with homogeneous pale eosinophilic cytoplasm and very pale to clear central areas (previous nucleus sites). Although GCs are present in a variety of odontogenic lesions notably the calcifying cystic odontogenic tumor (CCOT), their nature and process of formation remains elusive. The aim of this study was to investigate the role of Notch signaling in the cell fate specification of GCs in CCOT. Immunohistochemical staining for four Notch receptors (Notch1, Notch2, Notch3 and Notch4) and three ligands (Jagged1, Jagged2 and Delta1) was performed on archival tissues of five CCOT cases. Level of positivity was quantified as negative (0), mild (+), moderate (2+) and strong (3+). Results revealed that GCs demonstrated overexpression for Notch1 and Jagged1 suggesting that Notch1-Jagged1 signaling might serve as the main transduction mechanism in cell fate decision for GCs in CCOT. Protein localizations were largely membranous and/or cytoplasmic. Mineralized GCs also stained positive implicating that the calcification process might be associated with upregulation of these molecules. The other Notch receptors and ligands were weak to absent in GCs and tumoral epithelium. Stromal endothelium and fibroblasts were stained variably positive.
    Matched MeSH terms: Odontogenic Tumors/metabolism*; Odontogenic Tumors/pathology*
  3. Chong Huat Siar, Kok Han Ng
    J Nihon Univ Sch Dent, 1996 Mar;38(1):52-6.
    PMID: 8648412
    Two cases of either peripheral odontogenic fibroma (POF) (WHO type) or peripheral ameloblastoma are reported. Their immunohistochemical characteristics were investigated in an attempt to clarify their histogenesis. The results showed that the epithelial component of this neoplasm tended to retain its distinct odontogenic character and expressed a keratin profile different from that of the overlying oral epithelium from which both cases most probably originated. The connective tissue element of these tumors was vimentin-positive and S-100 protein negative, confirming their mesodermal nature but precluding the possibility of ectomesenchymal derivation. No reactivity for desmin was noted.
    Matched MeSH terms: Odontogenic Tumors/pathology*; Odontogenic Tumors/chemistry*
  4. Siar CH, Ng KH
    J Nihon Univ Sch Dent, 1993 Jun;35(2):134-8.
    PMID: 7692017
    Granular cell ameloblastoma (GCA) is a well recognized variant of follicular ameloblastoma with extensive granular cell change. In contrast, plexiform granular cell odontogenic tumor (PGCOT) is a rare and recently described lesion characterized histologically by a monophasic plexiform pattern of granular cells. In this paper, two cases of an unusual granular cell odontogenic tumor exhibiting combined features of these two entities are described along with their immunohistochemical characteristics. The granular cells of both the GCA and PGCOT areas showed similar patterns of expression for keratin and S-100, which differed from those of typical ameloblastoma. No reactivity for desmin or vimentin was noted. The histomorphologic and immunohistochemical features of these hybrid tumors suggest that the granular cells present have a common origin, most probably the odontogenic epithelium.
    Matched MeSH terms: Odontogenic Tumors/pathology*; Odontogenic Tumors/chemistry
  5. Sudiono, J., Zain, R.B.
    Ann Dent, 1998;5(1):-.
    MyJurnal
    The epithelial cystic linings and adjacent connective tissues of 61 cases of odontogenic cysts (radicular cysts[RC], dentigerous cysts[DC] and odontogenic keratocysts[OKC]) and unicystic ameloblastomas(UA) were described and compared histopathologically. The type of epithelium in relation to the presence of rete processes and the distribution of chronic inflammatory cells were analyzed statistically. Significant associations between the presence of rete processes in the non-keratinized epithelial linings and inflammation in the subjacent connective tissues of RC and DC were found in this study. There was also a statistically significant association between the presence of rete Processes and nonkeratinized epithelial linings in OKC. The results also showed that in inflamed OKC, the cystic lining epithelium exhibited hyperplasia indistinguishable from lining epithelium of RC and DC. This study further showed that ameloblastomatous-like epithelial cystic linings were present in inflammed odontogenic cysts. All except for one case of unicystic ameloblastomas in this study showed ameloblastomatous epithelial cystic linings. It is recommended that the lining epithelium of RC and DC be examined carefully in order to rule out OKC. Similarly, ameloblastomatous-like lining epithelium arising from chronic inflammation in RC and DC should be differentiated from true ameloblastomatous cystic lining. Such careful examinations are diagnostically important in view of the similarities of epithelial cystic linings of inflamed OKC with DC and RC aggressive behavior ofOKC and UA.
    Matched MeSH terms: Odontogenic Tumors
  6. Khoo SP, Ong ST
    Ann Dent, 1998;5(1):49-52.
    MyJurnal
    Odontogenic carcinomas of the jaws are subclassified into malignant ameloblastoma, ameloblastic carcinoma and primary intraosseous carcinoma arising from within the bone. These may arise from residual islands of epithelium derived from dental lamina or epithelial lining of dental cysts. Ameloblastic carcinoma is extremely rare. An aggressive case of ameloblastic carcinoma occumng in a 59-year-old Malay man is presented. Wide excision of the primary lesion with radical neck dissection was carried out. He developed lung metastasis 4 months post-operatively. Despite chemotherapy upon discovery of lung metastasis, he expired 7 months following the initial diagnosis.
    Matched MeSH terms: Odontogenic Tumors
  7. Abdulla AM, Sivadas G, Surej Kumar LK, Sheejith Hari Peeceeyen CS, Vedam V
    Case Rep Med, 2017;2017:9483738.
    PMID: 28883834 DOI: 10.1155/2017/9483738
    Ameloblastic fibroodontoma is a benign mixed odontogenic neoplasm considered in patients with asymptomatic swelling and unerupted teeth that exhibit histologic features between ameloblastic fibroma and complex odontoma. Radiographically, this lesion appears as radiolucency admixed with focal radio opaque masses of irregular shapes and sizes. This lesion is confirmed by the presence of proliferating odontogenic epithelium, ectomesenchyme, and dental hard tissue formation on pathological analysis supplementing clinical and radiographic findings. As this tumour is less commonly seen in routine clinical practice, ameloblastic fibroodontoma with detailed orofacial features and periodic approach to its diagnosis is discussed. This paper reports a case of ameloblastic fibroodontoma of the mandible in a 6-year-old male patient with an uncommon case presentation and review of the literature.
    Matched MeSH terms: Odontogenic Tumors
  8. Mutalik VS, Nichat P, Carnelio S, Solomon M, Radhakrishnan R
    J Contemp Dent Pract, 2014 Jan 1;15(1):119-21.
    PMID: 24939279
    Calcifying epithelial odontogenic tumor (CEOT) is a rare, benign, locally aggressive odontogenic epithelial tumor that affects the jaws. Although there are numerous reports on the variants of CEOT, occurrence of clear cells with complete absence of calcification has been a rarity. Histochemical analysis of tumor cells revealed glycogen granules with PAS staining, with absence of CD 1a staining in clear cells, while the amyloid-like deposit associated with clear cells showed green birefringence with Congo red. We report an unusual variant of CEOT occurring in a 27 years old male patient.
    Matched MeSH terms: Odontogenic Tumors/pathology*
  9. Ng KH, Siar CH
    PMID: 12738952
    Although rare, hard tissue deposits, namely dystrophic calcifications and cartilage, have been reported to occur in the connective tissue wall of the odontogenic keratocyst. However, dentinoid formation has not been previously documented. A case involving the left mandibular premolar-molar region in a 37-year-old Malay male is described here along with a brief review on the reported prevalence of hard tissue deposits in the odontogenic keratocyst. Differential diagnosis of this case from other dentinoid-forming odontogenic cysts and tumors-notably calcifying odontogenic cyst, odontoma, ameloblastic fibro-odontoma, central odontogenic fibroma and adenomatoid odontogenic tumor that may present with dentin/dentinoid formation-is discussed.
    Matched MeSH terms: Odontogenic Tumors/diagnosis
  10. Siar CH, Ng KH
    J Laryngol Otol, 1994 Mar;108(3):269-71.
    PMID: 8169519
    A case is described of ameloblastoma of the mandible presenting with multiple recurrences and subsequent extension to the maxilla with resultant transformation into an aggressive (malignant?) epithelial odontogenic ghost cell tumour. The latter is a rare, biologically virulent entity that affects mainly males, exhibits a preference for the maxilla and is histologically characterized by atypical malignant odontogenic epithelium associated with areas of ghost cell formation and varying amounts of dentinoid.
    Matched MeSH terms: Odontogenic Tumors/pathology*
  11. Ong ST, Shim CK, Ng KH, Siar CH
    J Oral Sci, 2004 Mar;46(1):55-9.
    PMID: 15141725
    Osteosarcomas are highly malignant neoplasms of bone that are challenging to diagnose. These neoplasms often show atypical behavior. In the initial phase they may present as nondescript bony swellings with an indolent growth rate, only to become overtly aggressive and malignant towards the later phase of the disease. Similarly, the histological growth pattern of this neoplasm can be quite diverse, presenting with areas that mimic benign myofibroblastic tumors, giant cell granulomatous conditions and partial encapsulation. The final diagnosis of an osteosarcoma is often reached after thorough sampling and examination of multiple biopsy specimens. All these clinical features and histological diagnostic difficulties were encountered in a case of osteosarcoma affecting the right mandible of a 62-year-old Chinese woman described here. The diagnostic lessons accrued from this case are discussed.
    Matched MeSH terms: Odontogenic Tumors/diagnosis
  12. Goh YC, Chan SW, Siar CH
    Malays J Pathol, 2019 Dec;41(3):303-311.
    PMID: 31901915
    INTRODUCTION: Ameloblastoma is a benign but locally invasive odontogenic epithelial neoplasm with a high recurrence rate after treatment. The two main subsets encountered clinically are unicystic (UA) and solid/multicystic ameloblastoma (SMA). Currently neoplastic progression of many tumour types are believed to be related to parenchyma-stromal cell-cell interactions mediated by cytokines notably interleukins (IL). However their roles in ameloblastoma remain ill-understood.

    MATERIALS AND METHODS: Thirty-nine formalin-fixed paraffin-embedded ameloblastoma cases comprising unicystic ameloblastoma (n=19) and solid/multicystic ameloblastoma (n=20) were subjected to IHC staining for IL-1α, IL-1β, IL-6 and IL-8. A semi-quantitative method was used to evaluate the expression levels of these cytokines according to cell types in the tumoural parenchyma and stroma.

    RESULTS: Major findings were upregulations of IL-1α and IL-6 in SMA compared to UA. Both cytokines were heterogeneously detected in the tumoural parenchyma and stroma. Within the neoplastic epithelial compartment, IL-1α expression was more frequently detected in PA-like cells in UA whereas it was more frequently encountered in SR-like cells in SMA. IL-6 demonstrated higher expression levels in the stromal compartment of SMA. IL-1β and IL-8 were markedly underexpressed in both tumour subsets.

    CONCLUSIONS: Overexpression of IL-1α in SMA suggests that this growth factor might play a role in promoting bone resorption and local invasiveness in this subtype. The expression levels of IL-1α and IL-6 in three cellular localizations indicate that parenchymal-stromal components of ameloblastoma interact reciprocally via IL-1α and IL-6 to create a microenvironment conducive for tumour progression.

    Matched MeSH terms: Odontogenic Tumors/metabolism
  13. Siriwardena BSMS, Udagama MNGP, Tennakoon TMPB, Athukorala DAADW, Jayasooriya PR, Tilakaratne WM
    PMID: 32782125 DOI: 10.1016/j.bjorl.2020.06.004
    INTRODUCTION: The adenomatoid odontogenic tumor is a relatively uncommon odontogenic neoplasm representing about 4.7% of all odontogenic tumors.

    OBJECTIVE: The aim of this study was to determine the demographic and clinical profile of the adenomatoid odontogenic tumors in a Sri Lankan population.

    METHODS: Data gathered from the cases received for a period of 38 years from the Department of Oral Pathology, Faculty of Dental Sciences, University of Peradeniya. Request forms, biopsy reports and electronic data base of the department were used to obtain relevant information. Demographic data including age, gender and location of the tumor were included in the analysis.

    RESULTS: Out of 116 cases of adenomatoid odontogenic tumor, the mean age was 21.02 ± 11.24. It occurs more fre quently in the second decade of life, more prevalent in females, most often associated with the maxilla, predominantly affecting anterior jaw bones and presenting mostly in the right side of the jaw bone. The results from the present study showed the statistically significant relationship with site of occurrence (maxilla/mandible) and age (p  0.05).

    CONCLUSIONS: Adenomatoid odontogenic tumor occurs more frequently in the second decade of life with a significant female predominance and the commonest site is anterior maxilla. This study revealed few differences on demographic and clinical presentations of adenomatoid odontogenic tumor from some regions of the world.

    Matched MeSH terms: Odontogenic Tumors
  14. Ibrahim N, Nazimi AJ, Ajura AJ, Nordin R, Latiff ZA, Ramli R
    J Craniofac Surg, 2016 Jul;27(5):1361-6.
    PMID: 27391504 DOI: 10.1097/SCS.0000000000002792
    The aim of this study was to describe the clinical features and expression of bcl-2, cyclin D1, p53, and proliferating cell nuclear antigen (PCNA) antibodies in syndromic (nevoid basal cell carcinoma syndrome [NBCCS]) and nonsyndromic patients diagnosed with keratocystic odontogenic tumor (KCOT).

    METHODS: This descriptive study comprised 5 patients of KCOT associated with NBCCS and 8 patients of nonsyndromic type treated in the Department of Oral Maxillofacial Surgery, Universiti Kebangsaan Malaysia Medical Centre between years 1998 and 2011. The clinical features (site, size, treatment, and recurrence), demographic characteristics, and immunohistochemistry results using antibodies of bcl-2, cyclin D1, p53, and PCNA were examined. The association of the antibody expression and the type of KCOT was analyzed using Fisher exact test.

    RESULTS: Altogether there were 13 patients, 5 with syndromic KCOT (1 patient met 3 major criteria of NBCCS) and 8 with sporadic KCOT. The age range for syndromic KCT was 11 to 21 years (mean 16.00 years, SD 4.36) and 10 to 54 years (median 24.50 years, interquartile range 19.00) for the nonsyndromic KCOT. Tumor recurrence occurred in 3 patients (7.7%); 1 patient from the syndromic and 2 patients from the nonsyndromic. The most positive expression was observed in PCNA for both the syndromic and nonsyndromic samples and the least positive expression involved the p53.

    CONCLUSION: PCNA, bcl-2 protein, and cyclin D1 expressions could be useful in evaluating the proliferative activity of the tumor and the aggressiveness of the clinical presentation; however, the authors would propose for larger sample size research for more definitive results.

    Matched MeSH terms: Odontogenic Tumors/diagnosis; Odontogenic Tumors/genetics*; Odontogenic Tumors/metabolism
  15. Sudiono, J., Zain, R.B.
    Ann Dent, 2003;10(1):-.
    MyJurnal
    Proliferating Cell Nuclear Antigen (PCNA) is one of the several markers of cellular proliferation. Epithelial proliferations play a significant role in the behaviour of odontogenic lesions. The objective of this study was to describe and compare the distribution of PCNA expression within the epithelial linings of odontogenic cysts. A total of 49 cases of odontogenic cysts consisting of 18 radicular cysts, 16 dentigerous cysts, 15 odontogenic keratocysts (OKCs) was studied. All tissues were processed routinely prior to embedding in paraffin. PCNA immunohistochemical staining was performed on 4 !-tm thick deparaffinized sections mounted on sialinized slides using the peroxidase antiperoxidase method. The distributions of PCNA expression in the cysts linings were noted and comparison was made qualitatively and quantitatively. PCNA labelling index was used for the quantitative assessment. The results showed that PCNA staining was distributed in the basal and supra basal cells for radicular cysts, dentigerous cysts, and OKCs. PCNA labelling index was highest in OKC (22.33±4.07). The high PCNA labelling index in OKC is indicative of high proliferative activity thus supporting previous reports of OKC as the most aggressive type of odontogenic cysts.
    Matched MeSH terms: Odontogenic Tumors
  16. Haragannavar VC, Tegginamani AS, Raju S, Kudva S, Peter CD, Shruthi DK
    Indian J Pathol Microbiol, 2019 2 2;62(1):3-6.
    PMID: 30706851 DOI: 10.4103/IJPM.IJPM_403_18
    Background: FHIT (Fragile histidine triad) a member of tumor suppressor family, has been extensively studied in many solid tumors including head and neck squamous cell carcinoma. Among all head and neck cyst and tumors odontogenic lesions account approximately 3%-9%. The molecular pathogenesis of these lesions is less explored. Defects in cell cycle regulators and tumor suppressor genes could result in the development of odontogenic cyst and tumors. Hence, we aimed to determine the significant role of a tumor suppressor gene FHIT in most commonly occurring odontogenic lesions mainly ameloblastoma, odontogenic keratocyst and dentigerous cyst.

    Subjects and Methods: Immunohistochemical analysis of FHIT was done in ameloblastoma, odontogenic keratocyst, dentigerous cyst and dental follicle. Interpretation of the stained slides were done using standard scoring criteria by two pathologist. The results were subjected for statistical analysis.

    Results: Expression of FHIT varied among the groups, with highest negative expression in ameloblastoma 44.4% followed by odontogenic keratocyst 14% and 100%positive expression was seen in dentigerous cyst. The expression levels between the groups were statistically insignificant.

    Conclusion: The varied expression or negative expression of FHIT could be considered as an indicator for aggressive behavior and transformation of preneoplastic/cystic epithelium.

    Matched MeSH terms: Odontogenic Tumors
  17. Ghazali, N., Zain, R.B., Samsudin, A.R., Abdul Rahman, R., Othman, N.H.
    Malaysian Dental Journal, 2007;28(2):83-91.
    MyJurnal
    A review of incident oral and maxillofacial biopsies in Kelantan from January 1994 to December 1998 was carried out to evaluate the scope of pathological lesions managed by the two main oral and maxillofacial units in this state. A total of 357 biopsy reports from incident cases of pathological lesions were reviewed. The biopsies were mainly from intra-oral sites (n=326, 91.3%). Females had more frequent oro-facial lesions compared with males (male:female ratio is 0.8:1). The Bumiputera ethnic group had the most number of biopsies (n=321; 90%). The three most commonly observed histopathological groups were the connective tissue hyperplasia (n=90; 25.2%), epithelial dysplasia and neoplasia (n=68; 19%) and salivary gland cysts/mucocele (n=56; 15.7%). The top five most frequent diagnoses were mucocele (n=56; 15.7%), squamous cell carcinoma (n=45; 12.6%), epulides (n=31; 8.7%), pyogenic granuloma (n=25; 7.0%) and fibroepithelial polyp (n=19; 5.3%). Oro-facial malignancies made up almost one-fifth of all diagnoses and squamous cell carcinoma was the most common sub-type. Lymphomas in the oro-facial region (n=8; 11.4%) were more common than basal cell carcinoma (n=7; 10%) and salivary gland malignancies (n=6; 8.5%). Epithelial jaw cysts consisted of 8.7% (n=31) of all diagnoses, where inflammatory types were more common than the developmental types. Odontogenic tumours consisted of 5.6% (n=20) of all diagnoses and ameloblastoma was the predominant type.
    Matched MeSH terms: Odontogenic Tumors
  18. Siar CH, Abbas SA
    PMID: 23601220 DOI: 10.1016/j.oooo.2013.02.013
    The aim of this study was to evaluate the expression and localization of tight junction proteins (TJPs) or claudins in the keratocystic odontogenic tumor (KCOT) and to correlate with its biological behavior.
    Matched MeSH terms: Odontogenic Tumors/pathology*
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