Question:medium
Intraoperatively which stain is used to view following lesion:
Intraoperatively which stain is used to view following lesion:
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Think of the metachromatic vital dye that dysplastic oral mucosa retains during surgery.
Updated On: Jun 22, 2026
- AgNo3
- Toluidine Blue
- Congo red
- Methylene blue
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The Correct Option is B
Solution and Explanation
Approach this as "how does a surgeon make an invisible margin visible during an oral cancer operation?"
The picture is of a suspicious red, eroded patch of oral mucosa concerning for dysplasia or early oral squamous cell carcinoma. The surgeon wants a quick chair-side / table-side test that lights up abnormal cells so the resection is complete.
The principle is vital staining: a dye applied directly to living mucosa that is selectively taken up by malignant/dysplastic cells. Cancerous cells divide rapidly, contain far more nuclear DNA/RNA, and have loosened (widened) intercellular junctions, so a nucleic-acid-binding dye penetrates and is retained there but rinses off healthy tissue.
The dye that does exactly this in the mouth is toluidine blue. It is metachromatic and binds nucleic acids, so dysplastic areas turn a deep blue while normal mucosa stays pale, giving a clear visual map.
Quickly ruling out the rest: silver nitrate ($AgNO_3$) is a cauterising/haemostatic agent, not a marker dye; Congo red is a laboratory histochemical stain for amyloid (green birefringence in polarised light); methylene blue is mainly used for sentinel lymph-node localisation and Barrett oesophagus chromoendoscopy. None of these is the intraoral lesion-mapping stain.
Therefore the stain used to view this oral lesion intraoperatively is Toluidine Blue (option B).
The picture is of a suspicious red, eroded patch of oral mucosa concerning for dysplasia or early oral squamous cell carcinoma. The surgeon wants a quick chair-side / table-side test that lights up abnormal cells so the resection is complete.
The principle is vital staining: a dye applied directly to living mucosa that is selectively taken up by malignant/dysplastic cells. Cancerous cells divide rapidly, contain far more nuclear DNA/RNA, and have loosened (widened) intercellular junctions, so a nucleic-acid-binding dye penetrates and is retained there but rinses off healthy tissue.
The dye that does exactly this in the mouth is toluidine blue. It is metachromatic and binds nucleic acids, so dysplastic areas turn a deep blue while normal mucosa stays pale, giving a clear visual map.
Quickly ruling out the rest: silver nitrate ($AgNO_3$) is a cauterising/haemostatic agent, not a marker dye; Congo red is a laboratory histochemical stain for amyloid (green birefringence in polarised light); methylene blue is mainly used for sentinel lymph-node localisation and Barrett oesophagus chromoendoscopy. None of these is the intraoral lesion-mapping stain.
Therefore the stain used to view this oral lesion intraoperatively is Toluidine Blue (option B).
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