Toluidine blue: Yet another low cost method for screening oral cavity tumour margins in Third World countries

Objective: to use toluidine blue intra-operatively to identify tumour involved margins after the removal of oral cavity squamous cell carcinoma, and to compare the findings with those of final histopathology. methods: the study was conducted at the aga khan university hospital from december 1, 2009, to march 14, 2010, and comprised 56 consecutive patients with biopsy-proven squamous cell carcinoma of oral cavity regardless of grade and stage of tumour. intra-operatively toluidine blue was used on the resected tumour margins and the staining patterns were assessed. results were then compared with the final histopathology report. results: a total of 11(19.64%) margins were positive with toluidine blue staining out of which 8 (14.28%) were false positive. sensitivity and specificity was found to be 100% and 84.9% respectively with a positive predictive value of 27.2%; a negative predictive value of 100%; and diagnostic accuracy of 85.71%. conclusion: toluidine blue costs only rs25 (usd 0.30) and takes only 5 minutes for application and interpretation. it can be used with significant confidence in smaller lesions (t-i and t-ii) as an alternative to frozen sections in developing countries where facilities are unavailable. its use in larger lesions (t-iii and tiv) remains the topic of controversy and awaits a multi centre trial with a larger cohort.