Papanicolaou Staining and Processing Troubleshooting Exercise Using Digital Pathology: Peer Comparison in an External Quality Assurance Setting

Abstract

Background: The Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) offers a comprehensive range of External Quality Assurance programs for all disciplines of pathology and is committed to delivering programs to advance outcomes in patient care and promote excellence in laboratory diagnostic and technical proficiency. Proficiency testing in cytopreparatory techniques became available for formal enrolment in 2018. The 2019 technical program focused on the demonstration of a laboratory to troubleshoot problems encountered during staining and processing. The exercise provided a peer comparison of a laboratory’s ability to (1) identify the problem viewed from a digital image and (2) describe the troubleshooting steps to rectify the problem using assessment guidelines. Methods: Ten troubleshooting exercises including whole-slide z-stacked virtual images, a reference slide, and an online Result Entry questionnaire were provided. Common staining and processing problems were demonstrated in these exercises. Multiple-choice responses were made available to participants for each case with 1 response requiring submission. Participants were then allowed free text to describe how they would rectify the problem. Results: Of the 72 participants who participated, 62 participants (86%) achieved a satisfactory assessment, 6 participants (8%) received a borderline assessment, and 4 participants (6%) received an unsatisfactory assessment. The average mark obtained was 32.7 out of a total of 45 marks, which equates to a satisfactory assessment. The highest mark obtained for this survey was 42.5. Conclusions: Quality cytopathology preparatory techniques are integral to mitigating the risk of diagnostic error. The digital pathology platform allowed homogeneity of samples for all participants and appeared to be a satisfactory mode for demonstrating the technical problems to participants. Laboratories participating in this survey showed good performance in identifying processing and staining problems on virtual images and working through the troubleshooting steps. The exercise also identified a method for troubleshooting formalin vapour-affected slides using citrate buffer which may be useful for laboratories following in-house validation.

Causation of cornflake artifacts: Possible association of poor dehydration with drying before mounting in Papanicolaou stain

“…Cornflake artifacts, which are peculiar artifacts commonly detected in cervical Papanicolaou (Pap) smears, are refractile brown or black deposits that cover the central portion of the cytoplasm of squamous epithelial cells, 1–3 which can thereby completely obscure the details of numerous cell nuclei, making microscopy difficult and increasing the risk of diagnostic errors 4,5 . Its entity is believed to be a bubble trapped on the cell surface under a coverslip, a trace of xylene evaporation during mounting.…”