Investigating the Role of Liquid Dish Washing Soap as a Substitute for Xylene in Routine Hematoxylin and Eosin Staining: Comparative Study
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Date
2018-01
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Addis Ababa University
Abstract
Background: One of the most important chemical in histopathology laboratory but potentially hazardous to the technologists is xylene. Histotechnologists and other workers in the histology laboratory are exposed to xylene during various procedures, especially during deparaffinizing tissue sections. Lack of proper disposal system of xylene and the laboratory workers poor preventive mechanism towards the chemical in daily activities are some of the reasons that make the impact of the exposure worse.
Objective: To investigate the role of liquid dish washing soap as a substitute for xylene in routine Hematoxylin and Eosin (H&E) staining procedure for biopsy sections.
Materials and Methods: One hundred forty one tissue blocks were used. Two sections from each paraffin block, a total of two hundred eighty two sections with 4μm thickness were included. From each pair of section, one was stained with conventional (routine) H&E staining procedure and the other with xylene-alcohol free (XAF) H&E staining procedure. Slides were scored using five parameters: Nuclear, cytoplasmic, clarity, uniformity, and crispness of staining. Slides that fulfilled at least three of the aforementioned parameters were considered adequate for diagnosis. Three different pathologists evaluated the slides independently. Z test and McNemar’s test were used to compare the difference between the two methods, p-value < 0.05 considered
significant.
Result: From the three, one pathologist reported that there is no difference between the paired sections on nuclear staining (Z=0.5, p>0.05). As reported by pathologists II(Z =0.6& 0, p >0.05) and III(Z =0.9 & 0.3, p >0.05), there is no significant difference between the paired sections on cytoplasmic and uniformity of staining. Pathologist III reported all slides stained by both
methods as “clear”, indicated no difference between conventional and XAF H&E stained slides. Pathologist I(Z =1.7, p >0.05) and III(Z =0, p >0.05) noted that both staining methods showed a crisp staining and there is no significant difference. Finally pathologists II(Z =1, p>0.05) and III (Z =0.6, p >0.05) showed that there is no difference between the two methods stained sections for diagnosis. All the above results are shown by “Z” test because both “Z” test’s and McNemar’s test p value lead to similar statistical conclusion. However, the result of pathologist I for XII crispiness of staining showed discrepancy, while “Z” test showed no significant difference, McNemar’s test indicated agreement between the methods.
Conclusion: Removing xylene from the routine staining procedure has many advantages. Replacing it with safer, cheaper and easily disposable reagent is ideal. Therefore, considering the advantages of the new method with regard to the pathologists report in this study, it is possible to say that XAF H&E staining procedure has the potentiality of being the new routine procedure in
histology laboratory.
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Keywords
Xylene, Deparaffinizing, Histotechnology, H & E, McNemar’s test, Z test