There is no absolute proof of which morphological type of non-invasive cancer develops to advanced cancer.
Traditionally, WHO epithelial dysplasia has been used to pathologically diagnose oral epithelial precursor lesions.
In 2005, squamous intraepithelial neoplasia (SIN1-3) were classified parallel to Head and neck tumours classification of WHO.
In the classification, each corresponds to the following: Mild dysplasia to SIN1, moderate dysplasia to SIN2, severe dysplasia and carcinoma in-situ to SIN3.
Oral cavity was discussed as epithelial precursor lesions, early intraepithelial tumor which differentiation is only seen in the surface area, as well as hypopharynx, larynx, trachea, and oropharyngeal.
In our country, this intraepithelial neoplasia was histopathologically known to some pathologist from the early stage. Mostly this was clinically treated as malignant tumor although there is no unified rule countrywide at the moment.
In 2010, oral intraepithelialneoplasia (OIN)/ carcinoma in-situ (CIS) was enrolled to Japan society for oral tumors as histological classification.
Because there are so many classifications that are discussed currently, people are confused of clinical correspondence, interpretation of each and which ones to use.
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