Comparison between Glass Slides Versus Digital Slides for Thyroid Cytology: A Step Towards Digital Cytology Workflow


Introduction: Transitioning to digital cytology is in its initial phase. As a first step towards digitization, we started scanning all cell-blocks and immunohistochemical stains for primary diagnosis of cytology cases at our institution. This study aims to compare thyroid cytology diagnosis using glass slides versus digital slides and is undertaken to test the feasibility towards transitioning to digital cytology workflow.

Material and Methods: A cohort of 32 cases of thyroid cytology was obtained after searching our laboratory information system (LIS) for thyroid cytology cases encompassing the spectrum of diagnostic categories in the Bethesda system for reporting thyroid cytology. The cases composed of unsatisfactory (n=7), benign (n=16), atypia of undetermined significance (n=6) and malignant (n=3). At our institution, all thyroid cases are processed as diff-Quik stained slides and a one Papanicolaou stained Thin Prep liquid-based preparation (LBP) and cell-block when requested by cytopathologist.  Whole slide images (WSIs) were created using Philips Ultra-fast scanner. Both glass and digital slides were previewed by 2 cytopathologists after a wash-out period of two-four weeks. Intra-observer concordance of >90% was set as a limit to consider the results to be satisfactory.

Results: Intra-observer concordance for viewer 1 was 78.12 % (25/32) and 75% (24/32) for viewer 2. Majority of the Thin Prep slides were out of focus (27/32). Although WSIs of majority of the thyroid cytology smears were optimal there were one or more smears per case with low cellularity that were out of focus. These are the major reasons for the discordance between glass versus digital thyroid cytology reads.

Conclusion: This limited sample study demonstrated moderate concordance (75-78%) for the diagnosis of thyroid cytology cases using digital pathology. Our study demonstrated that Philips Ultrafast scanner is not feasible to create WSIs of LBPs used for thyroid cytology and showed poor performance for thyroid cytology smears with low-cellularity. Next steps include comparison of WSIs created using different scanners like Leica and/or Huron for thyroid cytology.



  1. To assess the usefulness of digital pathology in cytology workflow


Presented by:


Himani Kumar, MD

Resident Physician

Wexner Medical Center, Ohio State University


She is a second-year resident in Pathology at Wexner medical Center, Ohio state university. She was born and raised in India where she completed her medical schooling and residency in Pathology. Her deep-rooted passion for pathology lies in the belief that an early diagnosis can wield the power to drastically alter the course of a patient’s illness. She has 9 publications in peer- reviewed journals. She seeks to delve into advanced techniques such as molecular pathology as well as exploring the integration of artificial intelligence and digitalization into the realm of pathology. In her free time, she enjoys gardening, cooking and spending time with family.