Evaluating Efficacy of Paraffin Oil, Isopropanol and Ethanol Mixture as Alternative for Xylene in Surgical Biopsy Tissue Processing by the Conventional Paraffin Wax Method: Comparative Study in Histopathology
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Date
2021-06
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Addis Ababa University
Abstract
Background: Major global mortality is due to non-communicable diseases with cancer predominance. Unfortunately, Cancers diagnosed at late to end stages in Africa. Histopathology diagnosis has tremendous value in the treatment, prognosis and follow up of cancer patients. Fixation, processing, embedding, sectioning, staining and evaluation of slides are mandatory
procedures in histopathology. These procedures use noxious and carcinogenic chemicals primarily xylene. However; xylene is hazardous chemical that causes muscular, neuron, ocular, reproductive, respiratory, immunological, hematological, renal, hepatic, cardiac effects. Fluid and vapors of xylene cannot be prevented with glove and masks. Hence there should be some
substitution mechanism which can minimize or replace use of xylene in histopathology laboratory.
Objective: This study aimed to evaluate the comparative efficacy of paraffin oil, isopropanol and ethanol mixture (PIE) as a bio friendly replacement for noxious xylene in surgical tissue processing with conventional paraffin wax method.
Method: Prospective cross-sectional method and purposeful sampling technique was used at St. Paul’s hospital millennium medical college pathology department from February 2019 up to December 2020 GC. A total of 112 samples were processed using new mixture and conventional xylene method. Block sectioning simplicity and slide quality for diagnosis were evaluated by histologists and pathologists using standard checklist respectively.
Result: According to the study, report of the three histologists revealed that 94.4% and 94.5% blocks were easy to produce good sections with paraffin oil, isopropanol and ethanol mixture and Conventional xylene methods respectively; indicating no statistical difference among methods (p=0.967). Evaluation of mounting, block storage stability and physical quality of sections confirmed adequacy in 98.2%, 99.1% and 98.3% respectively. This result showed no statistical significant difference with the conventional method (p=1.000)). The new xylene free method showed 95 % and 96.4% nuclear and cytoplasmic staining adequacy respectively.no statistical difference in both parameters recorded (p=0.602 and0.772 respectively) 95.3%, 96.8% and 95.5 % of stained slides which were processed with the new method revealed adequacy for clarity, uniformity and crispness of staining respectively indicating no statistical significant difference as p=0.073, 0.108, and 0.180 respectively. About 95.8% of total slides were adequate for diagnosis with the new method which was not statistically significant (p=0.668 & p= 0.229 by score and observant respectively).
Conclusion: The new mixture has comparable ability with that of xylene to clear surgical biopsy specimens during processing in histopathology.
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Keywords
Clearing, health hazardous, PIE mixture, Pathology, substitute, tissue processing.