Study On Clinicopathological, Cell Proliferation And Invasion Of Calcifying Epithelial Odontogenic Tumor

Objective: To investigate the clinicopathological and ultrastructural characteristics of calcifying epithelial odontogenic tumor and to report new variants, this should be helpful in differential diagnosis and further research. To observe the expressions of molecules relative to cell proliferation or tumor invasion in calcifying epithelial odontogenic tumor, this may lay a foundation for prognostic prediction.Materials and Methods: According to the classification of odontogenic tumor (WHO, 1992), 15 cases of calcifying epithelial odontogenic tumors were collected from 1970 to 2003. 15 cases of CEOT were stained with routine HE, PAS and Conge red stains and immunohistochemical stains with cytokeratin and type IV collagen antibodies and the ultrastructure of one fresh tumor was also observed. The expression of molecules relative tocell proliferation or tumor invasion, including PCNA, bcl-2, NF- kB, MMP2, MMP9, TIMP1, TIMP2 were examined by immunohistochemical SP and in situ hybridization technique.Results: Among 15 cases of CEOT, 10 tumors were intraosseous lesions and 5 tumors were extraosseous lesions. CEOT had no typical clinical appearances and intraosseous lesions showed various radiographic appearances and nine out of fifteen showed local invasion abilities. All tumors were treated by surgery conservatively or radically. There was no evidence of recurrence in any case. The histological characteristics included polyhedral epithelial cells with eosinophilic cytoplasm, amyloid material and calcification and there were four main histological patterns. Ultrastructurally, tumor cells and nuclei showed pleomorphism and many cellular organelle and tonofilament-like bundles distributed throughout the cytoplasm. The homogeneous substance consisted of dense accumulations of granulo-fibrillar material, which located intracellularly , stroma and between tumor cells, calcification could beobserved on occasion.The granulo-fibrillar material was sometimes found in membrane-bound globules. Cytokeratin AE1/AE3 and cytokeraatin 19 were expressed in tumor cells; however, cytokeratin and collagen IV were negative in amyloid material.In one intraosseous lesion and one extraosseous lesion, the tumor chiefly consisted of scattered small nests and cords of polyhedral tumor cells and clear tumor cells with vacuolated cytoplasm. Scarce calcification of homogenous materials was observed. There were a few; occasionally several; cells positive for CD1a, CD 68, HLA-DR and S-100 protein. Ultrastructural studies found Langerhans cells with indented nuclei and Birbeck's granules among tumor cells. In 4 cases combined epithelial odontogenic tumors, it was found that CEOT-like areas predominated in just one case; Furthermore, the polyhedral, eosinphilical tumor cells exhibited positive for cytokeratin 19, and those of the other 3 cases showed negative.PCNA was expressed in 13 cases of CEOT and bcl-2 protein was broadly located in tumor cells and on occasion within or nearby calcified amyloid material. The positive rate ofnuclear factor kB subunit p65 in tumor cells was higher significantly than that of in normal oral mucosa. The average positive rate of p65 was 26.7 percent in tumor cells and nuclear positive rate was approximately 8.7 percent. MMP2 was expressed in tumor cells and amyloid materials in 3 cases of local invasive CEOT. The positive rate of MMP9 was higher than that of MMP2. TIMP2 was located in tumor cells and stroma of all CEOTs. There was no significant difference on TIMP2 expression between in local invasive CEOTs and in no local invasive CEOTs. MMP9 mRNA showed higher positive level and broader distribution than MMP9 protein did. TIMP1 mRNA and its protein mainly distributed in tumor cells and nearly were negative in stroma. The distribution of TIMP1 mRNA was similar to that of MMP9 mRNA.Conclusions: The calcifying epithelial odontogenic tumours located either intraosseouly or extraosseously and there were different clinical appearances between intraosseous lesion and extraosseous lesion and intraosseous lesion...