Toluidine blue: As an adjuvant screening tool

Abstract

Early detection and preventing the progression of potentially malignant disorders (PMDs) help in decreasing the incidence and improving the survival of those who develop oral cancer. The content of DNA and RNA is more in dysplasia and in situ carcinoma than the normal surrounding oral epithelium, the use of in vivo staining, by means of toluidine blue dye, is based on the fact that it is an acidophilic dye that selectively stains acidic tissue components such as DNA and RNA. Toluidine blue staining is considered to be sensitive in identifying early oral and oropharyngeal premalignant and malignant lesions. The results of the clinical evaluation, the toluidine blue test and histology, were compared in order to calculate the sensitivity (true-positivity) and specificity (true-negatives). According to the clinical examination, sensitivity was 53% while for toluidine blue staining, it reached 88.4% (p = 0.0007). Specificity was 76% for the clinical examination and 73.6% for toluidine blue staining (p = 0.79). The positive predictive value for clinical examination was 78.9% and 82% for toluidine blue staining (p = 0.85). The negative predictive value for clinical examination was 50% and 82.3% for toluidine blue staining (p = 0.0073). Our observations suggest that toluidine blue can act as a helpful adjuvant for biopsy in clinically suspicious lesions. So that toluidine blue negative lesions need not to be subjected to biopsies thus saving time and resourses. We conclude, toluidine blue stain could be a useful aid for clinically suspicious lesions in order to establish whether the lesions are at high risk of progression to malignancy and to contribute to an early diagnosis of oral and oropharyngeal cancer. Further studies with larger sample sizes have to be done to make the use of toluidine blue more widespread.