Reevaluation of toluidine blue application as a diagnostic adjunct in the detection of asymptomatic oral squamous carcinoma: A continuing prospective study of oral cancer III

Abstract

This study was initiated to evaluate toluidine blue application as a worthwhile and simple diagnostic adjunct to clinical impressions. In an attempt to decrease false positives, a 10–14 day waiting period was initiated to allow inflammatory lesions to resolve before application of stain. Using toluidine blue applications with 235 prospectively documented persistent lesions (105 carcinomas and 130 non-malignant lesions) resulted in a false negative rate (underdiagnosis) of 6.7% and false positive rate (overdiagnosis) of 8.5%. Using clinical criteria alone resulted in a false negative rate of 4.8% but with a tendency to overdiagnose—28.5% false positives. Combining both diagnostic modalities reduced the false negative rate to 1.9%, i.e., only two of the 105 cancers were not considered significant by toluidine blue stain or clinical impression. This staining technique appears to offer a feasible diagnostic “control” over the subjective impression of the clinician. Persistent lesions that stain with toluidine blue should be considered carcinoma unless proven otherwise by biopsy.