Vital Staining

Vital staining of the oral epithelium has been suggested as a means of surveillance in patients who are at risk of developing oral cancer. 

Stains used - 

• Toluidine blue 
• Methylene blue 
• Lugol's iodine 
• Acetic acid 

Toluidine blue staining

• Simple, inexpensive, and sensitive chair side test. 
• Sensitive adjunct tool for the identification of early oral squamous cell carcinoma (OSCC) and high-grade dysplasia. 
• Stains mainly two types of lesions:  
  • Squamous cell carcinoma and  Inflamed traumatic tissue 
• Toluidine blue - acidophilic metachromatic dye of thaizine group - selectively stains acidic tissue components such as DNA and RNA 
• It is a topical dye - gets concentrated in cells with abundant nucleic acid.  
• Stains to the depth of 2-10 cell layers - reflects only the epithelial changes.  
• Malignant epithelium - contain wider intracellular canals -  a factor that enhances penetration of the dye 
• Interpretation –  
  • Dark blue color : Positive for lesions suspicious malignancy 
  • Light blue         : Positive for premalignant lesions proved otherwise by biopsy 
  • Sensitivity and specificity of toluidine blue were calculated to be 86.36% and 76.9% respectively 

Methylene Blue Staining

• Recently studied dye for detecting oral cancer 
• Application is limited in detecting oral cancer 
• Local, stippled, patchy, and deep blue stains are marked as positive reaction 
• Wide, shallow, or faint blue stains are marked as negative reaction 

Lugol's Iodine Staining

• The basic principle with iodine staining is its affinity for carbohydrates and starch in the tissues.
• As the malignancy is associated with reduction in the glycogen content of the tissues, the malignant tissue remains unstained and on the contrary the normal epithelium gets stained brown or black.

Acetowhite Staining

• Component in other staining techniques - TB and chemiluminescence for cancer screening - used in the concentration of 1% acetic acid. 
• Inexpensive and easy to use. 
• A positive finding -  opaque white. 
• Negative finding - no change or changes to transparent white. 
• It acts by causing dehydration of the cells, thereby producing a white appearance. 
• Higher nuclear content in premalignant and malignant lesions reacts with the acetic acid producing a acetowhite appearance.

Double Staining

• Toluidine Blue and Lugol's iodine combination has been used. 
• Toluidine Blue will stain the abnormal epithelium. 
• Lugol's solution binds to glycogen present in the normal epithelium. 
• Area stained blue indicates the existence of carcinoma, the area stained brown belongs to normal squamous mucosa and the area between both the colors clarifies the invasive lesion of carcinoma 

These are a few of the staining techniques used as a chairside diagnostic aid in oral cancer detection. These are preliminary methods and the findings have to be confirmed with other modalities of diagnosis such as biopsy and other aids. 

Article by Dr. Siri P.B.