Differentiating vulvar intraepithelial neoplasia from nonneoplastic epithelial disorders. The toluidine blue test.

OBJECTIVE To determine the effectiveness of the toluidine blue test in the differentiation of vulvar intraepithelial neoplasia (VIN) and nonneoplastic epithelial disorders (NNEDs). STUDY DESIGN This retrospective clinical study included all women with VIN (n = 24) and NNED (n = 72) referred to a vulvar clinic at a university hospital during a two-year period. Vulvoscopy, staining of vulvar epithelium with 1% toluidine blue and punch biopsy were performed. RESULTS Vulvar epithelium demonstrated toluidine blue staining in 100% of the patients with VIN 3, in 83% of women with VIN 1-2, in 50% of the women with squamous cell hyperplasia and in 10% of the women with lichen sclerosus. The differences in staining between the groups were statistically significant (P < .001). The sensitivity of toluidine blue staining for the detection of VIN was 92%; the negative predictive value 96% in teh investigated cohort. The specificity for strong staining was 88%. CONCLUSION The toluidine blue test is an inexpensive and reliable method of separating VIN from hyperplastic NNED areas and choosing a biopsy site on the vulva.