Abstract Objectives: This study approaches the history of reclassifications and redefinitions around the odontogenic keratocyst (OK), as proposed by the World Health Organization (WHO), and aims to understand the impact of those changes on the prevalence and epidemiology of odontogenic tumors (OTs). Methodology: Cases of OTs diagnosed in an Oral Pathology service between January 1996 and December 2016 were reviewed. Demographic data of patients such as age, gender and site of lesions were retrieved from their respective records. Results: Within the studied period, 7,805 microscopic reports were elaborated and 200 (2.56%) of these were diagnosed as OTs. Out of these 200, between 1996 and 2005, prior to the 2005 WHO classification, there were 41 (20.5%) OTs cases, being odontoma the most frequent (23; 56.09%), followed by ameloblastoma (8; 19.51%) and myxoma (03; 7.31%). Between 2006 and 2016, after the previous 2005 WHO classification there were 159 (79.5%) OTs, being odontogenic keratocystic tumor (KCOT) the most frequent (68; 42.76%), followed by odontoma (39; 24.52%) and ameloblastoma (21; 13.20%). Conclusions: As of today, the most recent WHO classification to be followed brings KCOT back to the cyst category, which will impact on the prevalence and epidemiology of OTs; thus, this study was able to identify a considerable increase (287.80%) in the prevalence of OTs when the 2005 WHO classification was utilized. Despite being an important academic exercise, classifying odontogenic lesions and determining whether to place the odontogenic keratocyst in a cyst or tumor category is crucial to establish the correct diagnosis and treatment to follow, whether by oral medicine or oral surgery specialist, or by the general practitioner.

Vimentin is a cytoeskeletal intermediate filament protein commonly observed in mesenchymal cells; however, it can also be found in malignant epithelial cells. It is demonstrated in several carcinomas, such as those of the cervix, breast and bladder, in which it is widely used as a marker of the epithelial to mesenchymal transition that takes place during embryogenesis and metastasis. Vimentin is associated with tumors that show a high degree of invasiveness, being detected in invasion front cells. Its expression seems to be influenced by the tumor microenvironment. The aim of this study was to evaluate vimentin expression in head and neck squamous cell carcinoma (HNSCC) cell lines, and to investigate the contribution of the microenvironment to its expression. HNSCC cell lines (HN6, HN30 and HN31) and an immortalized nontumorigenic cell line (HaCaT) were submitted to a three-dimensional assay with Matrigel. Cytoplasmatic staining of the HN6 cell line cultured without Matrigel and of the HN30 and HN31 cell lines cultured with Matrigel was demonstrated through immunohistochemistry. Western Blotting revealed a significant decrease in vimentin expression for the HN6 cell line and a significant increase for the HN30 and HN31 cell lines cultured with Matrigel. The results suggest that vimentin can be expressed in HNSCC cells and its presence is influenced by the microenvironment of a tumor.