Chromium pigment removal is accomplished with which condition?

• A. 1% HCl in 70% alcohol for 30 minutes
• B. Iodine followed by Sodium Thiosulfate
• C. Alcoholic picric acid
• D. Hot water rinse

Answer: (A)

Chromium pigment removal relies on a chemical decolorizer that can interact with and dissolve the chromium-containing pigment in the tissue without destroying the rest of the stain. Using a mild acid in alcohol, specifically 1% hydrochloric acid in 70% ethanol, provides just enough acidity in a medium that solubilizes or bleaches the chromium pigment. The 30-minute exposure is long enough to remove the pigment but short enough to preserve tissue morphology and the integrity of other stains.

Other options aren’t the right fit for chromium pigment removal. Iodine followed by sodium thiosulfate targets iodine-based residues and is used for decolorizing certain stains rather than chromium pigments. Alcoholic picric acid serves different differentiating or staining roles and isn’t a standard method for stripping chromium pigment. A hot water rinse won’t effectively remove the stubborn chromium pigment and can cause tissue swelling or other issues.