Evaluation of Liquid Based Cytology for Tongue Squamous Cell Carcinoma: Comparison with Conventional Cytology

Oral exfoliative cytology is now used by general practitioners in Japan to screen for oral cancer. With conventional cytology, however, the number of cells that can be sampled is small. Moreover, cell deformation and piling of cells when preparing specimens has been reported. The purpose of this study was to compare conventional and liquid based cytology (LBC), which has been employed with increasing frequency in recent years. We believe that identifying potential pitfalls in oral exfoliative cytology will help improve diagnostic accuracy. A total of 153 patients with tongue squamous cell carcinoma who were diagnosed and treated initially at our hospital between January 2000 and December 2010 were included. Of these, 124 underwent conventional cytology, while the remaining 29 underwent LBC. Histopathological and clinical findings were used as criteria. Conventional cytology yielded a positive rate of 54.8% and LBC 79.3%, while values of 28.2% and 13.8% were obtained for a suspected positive rate, respectively. Liquid based cytology yielded a significantly higher percentage of accurate diagnoses and fewer suspected positives (p<0.05) in cases clinically classified as endophytic and those classified as ulcerative in terms of clinical growth pattern. No significant difference was observed between conventional cytology and LBC in cases of an infiltrative growth pattern, however.The present results suggest that LBC is superior to conventional cytology in achieving an accurate diagnosis based on oral exfoliative cytology. The present findings also suggest that exophytic type, and especially leukoderma type clinical growth patterns constitute pitfall cases in oral exfoliative cytology.