Effectiveness of toluidine blue as an aid to biopsy in the diagnosis of DMBA-induced hamster pouch dysplasia and carcinoma

Abstract

The left cheek pouches of 40 male Syrian hamsters were painted twice weekly with 0.5% 7, 12 dimethylbenz (α) anthracene (DMBA) in liquid petrolatum. At the end of 4, 8, and 15 weeks, 1% toluidine blue was applied to the pouches, followed by blotting with 1% acetic acid solution. The pouches were removed and fixed in 10% formalin. Routine histologic sections were prepared of both clinically toluidine blue-stained and adjacent nonstained areas. An additional 33 hamsters were similarly treated with DMBA for 13 weeks and maintained for an additional 12 weeks prior to toluidine blue application, removal and processing of pouches. With increased age of the lesions, a reversal of false-positive to false-negative toluidine blue-stained areas was found. In early lesions, dysplastic tissue could not be distinguished from nondysplastic tissue by use of toluidine blue clinical staining. In older lesions, toluidine blue was of very limited value in clinically delineating margins of dysplastic tissue.