Carcinoma in-situ of the oral mucosa: Its pathological diagnostic concept based on the recognition of histological varieties proposed in the JSOP Oral CIS Catalog ★

ObjectiveThis article documents the process that led to the publication of the “Oral CIS (JSOP) Catalog” by the Working Committee on New Histopathological Criteria for Borderline Malignancies of the Oral Mucosa, a group which was organized within the Japanese Society of Oral Pathology between 2004 and 2007.MethodsThe committee collected 160 cases histologically diagnosed as oral carcinoma in-situ (CIS) at 20 hospitals to which the committee members belonged, and five sets of hematoxylin and eosin stained sections of those cases were circulated in five routes among 25 committee members for reviewing for their own diagnoses. Their diagnoses were collected, and cases diagnosed as CIS by more than 70% of the members were selected for further discussion.ResultsCommittee members wanted to emphasize that oral CIS contained greater histological variety than had previously been defined, and they came to the eventual conclusion that two major histological variations of oral CIS, basaloid and differentiated, were distinguishable. In particular, they emphasized that oral CIS had a definite tendency toward keratinization or that it was well differentiated. They also recommended the use of immunohistochemistry for Ki-67 and keratin subtypes as an essential aid tool for oral CIS diagnosis.ConclusionBy referring to the Catalog, which explains histopathological variations, pathologists can more easily make a diagnosis of oral CIS, and oral surgeons can carry out appropriate clinical interventions for treating oral borderline malignancies.