Histopathological assessment of oral leukoplakia. Osteonectin as possible biomarker for further diagnostics.

Clinical evaluation of oral leukoplakia (OL), confirmed by the histological evaluation of the suspected area, provides the gold standard for diagnostics of this pathology. The aim of present study was to encrypt the significance of the histopathological results (oral intraepithelial neoplasia - OIN, WHO 2005, Ljubljana classification systems) of OL. The usefulness of osteonectin as a biomarker of changes in the oral cavity epithelium was evaluated. IRS Score to evaluate osteonectin (SPARC - secreted protein acidic and rich in cysteine) production in oral mucous tissues was modified, with the aim of adapting the diagnostic measurements to the OL cell environment. In total, 37 formalin-fixed, paraffin-embedded (FFPE) blocks from patients with clinically diagnosed OL, and 29 FFPE blocks from patients with OSCC were evaluated. The OIN and system from Ljubljana were compared, to adjudicate which was most compatible with WHO 2005 histopathological assessment. Increased production of SPARC was observed, with the progression in severity of pathological changes in the oral mucosa, from simple hyperplasia, through dysplasia, to OSCC. The WHO 2005 and the OIN classification systems can be applied interchangeably.