Combined epithelial odontogenic tumors are very rare and represent hybrid lesion comprising adenomatoid odontogenic tumor intermixed with calcifying epithelial odontogenic tumor. The authors present 3 cases of combined epithelial odontogenic tumor which contained diagnostic areas for both adenomatoid odontogenic tumor and calcifying epithelial odontogenic tumor. Their behaviour and histogenesis were discussed.

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.

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

The adenomatoid odontogenic tumor(AOT) is a benign tumor of odontogenic epithelium characterized by slow but progressive growth and rare recurrence. Tumor growth may cause displacement of teeth rather than root resorption. The AOT appears in 3 clinicotopographic variants such as follicular, extrafollicular, and peripheral. The follicular AOT mimics a dentigerous or follicular cyst and the extrafollicular cyst does a residual cyst, globulo-maxillary cyst and lateral periodontal cyst. Although over 750 cases of AOT were reported in the literature, clinicopathologic parameters of AOT in Koreans has not been investigated. 22 cases of AOT were retrieved from the files of the department of Oral Pathology, Seoul National University Dental Hospital and their clinicopathologic findings were reviewed. The central type accounts for 95%, 72% of which are follicular. The follicular and extrafollicular varients together are more commonly found in the maxilla than in the mandible with a ratio of 4.5:1. Age distribution showed that 59% of AOTs were diagnosed in the second decade of life, and mean age was 18.5 years. The female to male ratio was 3.4:1. All variants of AOT showed identical histologic features.