RESUMO
OBJECTIVES: This study assessed the efficacy of using oral liquid-based brush cytology and cell block immunocytochemistry in the diagnosis of oral leukoplakia as minimally invasive diagnostic adjuncts. METHODS: Seventy-two patients diagnosed clinically with either oral leukoplakia (OLK) or oral squamous cell carcinoma were included. Oral brush samples using Orcellex® brushes were obtained from all participants directly before undergoing surgical biopsy. Cell blocks were prepared for all samples and assessed for cytomorphology and immunocytochemistry of DNA mismatch repair proteins (MSH-6, MSH-2, MLH-1 and PMS-2). A combined index score of immunocytochemistry expression and cytology grading was compared against the gold standard (histopathological diagnosis). RESULTS: A significant association was observed between the cytological assessments of oral liquid-based brush cytology samples and the histopathological diagnosis (P < .005). In addition, there was a significant inverse correlation between the grade of oral epithelial dysplasia and the cumulative score of the studied DNA mismatch repair proteins (P < .005). Grading criteria for both oral liquid-based brush cytology and immunocytochemistry cumulative index scores are proposed based on the analysis of receiver operating characteristic curve coordinates. The diagnostic accuracy of this approach was outstanding in terms of discrimination between the presence or absence of oral epithelial dysplasia (0.961) and squamous cell carcinoma (0.977) separately. CONCLUSION: Oral liquid-based brush cytology cell block immunocytochemistry provides a reliable strategy to investigate oral mucosal epithelial disorders. This approach presents a minimally invasive, highly accurate and non-technically demanding method for the surveillance of oral potentially malignant disorders and squamous cell carcinoma.