Since vital staining has been advocated as a sensitive method of displaying
epithelial atypia, 14 oral squamous cell carcinomas were stained immediate
ly preoperatively with toluidine blue and then resected 1 cm outside clinic
ally abnormal or positively staining tissue. The integrity of the entire ti
ssue margin was histologically examined in each case. Whilst vital staining
delineated all 14 invasive carcinomas at the centre of each resected speci
men, 10 foci of carcinoma-in-situ or severe dysplasia were identified not t
o have stained at the resection margins. Toluidine blue may, therefore, be
an adjunct in identifying invasive tumour at mucosal resection margins. How
ever, it would appear to be of no benefit in delineating positive resection
margins due to carcinoma-in-situ or severe dysplasia, and hence it may be
of little value in reducing the incidence of local recurrences.