Alternate chromogens as substitutes for benzidine for myeloperoxidase cytochemistry.

Area of Science:

• Hematology
• Clinical Pathology
• Cytochemistry

Background:

• Myeloperoxidase (MPO) staining is crucial for leukemia classification.
• Benzidine dihydrochloride, a traditional MPO chromogen, is now a regulated carcinogen.
• Clinical laboratories face challenges in MPO staining due to benzidine restrictions.

Purpose of the Study:

• To evaluate alternative chromogens for MPO staining.
• To assess the utility of diaminobenzidine and Hanker-Yates reagent as substitutes for benzidine dihydrochloride.
• To determine if these alternatives meet clinical standards for leukemia classification.

Main Methods:

• Twenty-two leukemia and normal control specimens were stained.
• Stains were evaluated using benzidine dihydrochloride, diaminobenzidine, and Hanker-Yates reagent.
• Three expert observers assessed stain quality, MPO positivity, and overall acceptability in a blind study.

Main Results:

• Substitute chromogens, diaminobenzidine and Hanker-Yates reagent, demonstrated adequate MPO staining.
• Observer ratings indicated comparable quality to benzidine dihydrochloride.
• No significant differences in tinctorial distinction or smear quality were noted.

Conclusions:

• Diaminobenzidine and Hanker-Yates reagent are suitable alternatives for MPO staining.
• These methods offer clinical utility and can replace restricted benzidine dihydrochloride.
• Validated alternative chromogens ensure continued MPO-based leukemia diagnosis.