Rapid staining using toluidine blue: a reliable method for quick diagnosis in ultrasound-guided aspiration cytology.

Rapid staining of ultrasound guided aspirates is an accepted procedure for evaluation of adequacy and rapid diagnosis (RD). We have assessed the reliability of Toluidine blue stain in this regard, which has not been previously reported. 295 ultrasound guided aspirates performed over a 13 month period were studied. 59 aspirates were inadequate for RD. 103 cases were called malignant on RD of which 101 were confirmed, and 2 cases were considered highly suspicious on final diagnosis. Of 34 cases considered suspicious on RD, 32 were either signed out as malignant or considered highly suspicious while 2 cases were benign. Of 56 cases considered benign on RD, 49 were confirmed, 2 were suspicious for malignancy and 5 cases had inadequate material on final diagnosis. All 43 inflammatory lesions on RD were confirmed. The overall sensitivity for a malignant/suspicious for malignancy diagnosis was 98.54% on RD while specificity was 97.99%. Sensitivity and specificity for an inflammatory condition was 100%. Toluidine blue staining is not only a reliable method for rapid staining and diagnosis, it also permits preservation of cytological material by destaining and restaining with permanent stains.