Assessment of Cellular Proliferation in Oral Verrucous Carcinoma and Well-Differentiated Oral Squamous Cell Carcinoma Using Ki67: A Non-Reliable Factor for Differential Diagnosis?

Background: Non-invasive oral verrucous carcinoma (OVC) and invasive well-differentiated oral squamous cellcarcinoma (OSCC) have similar histopathologic findings but different biological behavior. These two malignanciesmust be correctly differentiated by pathologists. The aim of this study was to determine immunohistochemical(IHC) expression of Ki67 in OVC and well-differentiated OSCC.
Methods: Expression of Ki67 was evaluatedby IHC in 15 cases of epithelial hyperplasia with no dysplasia (A group), 15 cases of OVC (B group), 12 casesof microinvasive OSCC(C group) and 15 cases of well-differentiated OSCC (D group).
Results: There was asignificant difference in Ki67 expression based on pattern distribution of immunostaining positive cells, withquantitative and semi-quantitative analyses, among the four groups ; also, between A group and each of theother three groups (P= 0.0001). But there was no significant difference between B and C, C and D, and B and Dgroups ( P> 0.05 ).
Conclusions: The three evaluation methods of Ki67 expression showed Ki67 (Mib-1) is nota good immunohistochemical marker to assess invasion status and differentiate OVC from well-differentiatedOSCC; also, it cannot be used as a diagnostic tool to distinguish between variants of OSCC with similar grade.