With vital GSI-IX staining with iodine, we resected tumor to detect surgical margin of 5 mm distance from iodine unstained area (IU) (Fig. 4). The purpose of our study was to determine the usefulness of vital staining with iodine in deciding the surgical margin. One hundred and two patients diagnosed with T1 and early T2 OSCC between 1987 and 2006 were selected at the Department of Oral and Maxillofacial Surgery, Tokyo Dental College. We have already gotten an official approval from the ethical committee of Tokyo Dental College. We classified the

patients into two categories as follows: Group 1, where no iodine staining was carried out, all treated between January 1987 and December 1996 (41 cases); and Group 2, where iodine-staining was carried out, all treated between January 1997 and December 2007 (61

cases). We compared clinical and pathological buy ABT-199 histories between these two groups. First, in positive rates of second primary cancers, the results revealed that patients in Group 1 (17.1%) were significantly higher than those in Group2 (4.9%) (Fig. 5A). Next, in positive rates of pathological findings of surgical margin, the epithelial dysplasia-positive rate in Group 1 (26.8%) was higher than that in Group 2 (8.2%) (Fig. 5B). Finally, there were surgical margin-positive in 2 cases in Group 1 (4.9%). We suggest that the iodine staining method is a useful tool in deciding surgical margin in early OSCC. A histochemical and ultrastructural study on the localization of glycogen in normal and hyperkeratotic oral epithelium in humans has demonstrated that glycogen content is inversely related to the degree of keratosis, suggesting a role for glycogen in keratinization [18]. Basically, normal tissue would stain brown, while proliferating epithelium would be unstained or would stain poorly [19]. However, there are few reports on the investigation of IU and malignant potentiality. To clarify the correlation between IU and epithelial dysplasia, we examined the existence of glycogen

and changes in Proliferating Cell Nuclear Antigen (PCNA) in PAK5 tumor suppressor gene expression (p53) in the dysplastic epithelium using immunohistochemical and ultrastructural methods. Subjects are thirty cases of T1 and early T2 OSCC. Based on the WHO classification (2005), we classified the epithelial dysplasia histopathologically into thirty specimens with normal mucosa, twenty specimens with mild, twenty three specimens with moderate and twenty three specimens with severe epithelial dysplasia from thirty cases [6]. There were no significant differences between the normal epithelium (43.0%) and the mild dysplasia (45.5%) in terms of the ratios of PAS positive cells and their distribution (Fig. 6 and Table 1). However, PAS staining area of the moderate and severe dysplasia (13.9%) decreased more significantly than those of the normal epithelium (p < 0.01).