Cell blocks from Cytopathology samples have always had value in the diagnostic process as a complement to the traditional Cytopathology stains – Papanicolaou and Romanowsky. This has become more important to provide material for Immunocytochemistry to refine malignant diagnosis, and more recently, for the use of molecular testing to aid in the choice of tailored chemotherapy regimens. If this information can be obtained from Cytopathology samples, which are less invasive than biopsy samples, the patient will benefit. A variety of preparation methods are available for the preparation of cell blocks from cells from Diagnostic Cytopathology samples. The most popular methods will be discussed and how they can be used to optimise the quality of cell preservation if used correctly. Information garnered from the results of the recently introduced UK NEQAS CPT Diagnostic Cytopathology Cell block scheme will be presented and how this information can be circulated to laboratories experiencing difficulties with their preparation methods as an advisory service. This will include. • Understanding the clinical importance and diagnostic purpose of correct procedures in Diagnostic Cytopathology Cell Block preparation. • Identifying and determining factors affecting best practice and quality in Diagnostic Cytopathology Cell Block practice and how to resolve them. • Identifying and understanding the causes of artefacts experienced in Diagnostic Cytopathology Cell Block preparation methods and how to eliminate and prevent them.

P11- Participating In A Digital Diagnostic Cytopathology Interpretive Proficiency Testing (iEQA) Scheme -Helen Naylor, Anna Patterson, Chantell Hodgson, Ashley Makela

The iLabXCell Digital Diagnostic Cytopathology Interpretive Proficiency Testing Scheme or iEQA is facilitated by UK NEQAS Cellular Pathology Technique (CPT), and is designed to promote quality, excellence, and education for all involved in screening and reporting of Diagnostic Cytopathology. It is open to medical and non-medical staff, trainees, advanced practitioners, and staff associated with Cytopathology. iEQA provides superior, outstanding, and representative case examples for individuals to examine in a remote setting and submit an opinion via the user-friendly digital platform. Offering 2 circulations annually it provides • Easy access for registration • Ability to choose specimen types • Advanced slide viewing • Clinical details to assist diagnoses • Categorisation of images using benign or malignant

Flexibility Remote learning allows participants to continue learning alongside their peers, in an environment accommodating their needs. It allows the flexibility of international participants to access the platform at any time, convenient to them. Remote learning via the iEQA platform, offers the flexibility for users to pick up learning where they left it – anywhere, anytime, from any location. Self-paced learning Traditional learning has long failed to acknowledge the individualised nature of learning, opting instead for a generalised approach that may not be optimised for everyone. One of the many benefits of this iEQA is providing participants more independence to: • Spend more time on cases/case types they find difficult • Revisit the images as often as they need

Environmental benefits Digitising slides has led to a decrease in physical resources previously necessary for iEQA to function. Everything participants need is accessible on-line, eliminating the historical environmental impact and the time taken for circulations to be distributed and completed.

Future developments An on-line educational image library, containing images of Diagnostic Cytopathology cases of urines, serous fluids, respiratory and head and neck cases used in previous circulations for educational and training purposes.

Research Requires Flexibility: Protease-Free Permeabilization Expands FISH Tissue Applications.-Andrelie Branicky, Shared Laboratory Resources, Lerner Research Institute, Cleveland Clinic, Cleveland, OH

Fluorescence in situ hybridization (FISH) visualizes the presence of a specific DNA or RNA sequence in a tissue sample or cell. This method, particularly the mRNA version, detects gene expression when protein might not be present or IHC is impossible. FISH combined with immunohistochemistry enables spatial transcriptomics, which provides significantly more information about the tissue microenvironment.

Formalin-fixed paraffin-embedded (FFPE) tissues are the standard for tissue preservation in the clinical world. Most commercial mRNA probe and amplification systems are built around the model of FFPE tissue that can withstand harsh protease permeabilization. In the research world, tissues are fixed in different fixatives for varying times; all at the discretion of the investigator instead of an organization like the CLIA.

Given the wide range of tissue preparations, the HCR automated FISH-ISH protease-free program provides the flexibility to combine FISH and fluorescent immunohistochemistry on tissue fixed in a variety of ways such as: 10% NBF, Histochoice (a glyoxal-based fixative), and methanol/acetic acid, with only minor changes to the basic protocol. Additionally, the lack of harsh protease pre-treatment maintains tissue integrity and morphology for staining and imaging.

The Development of a Cocktail of Microglia and GFAP For Easy Diagnosis - Anisha Bhasin B.S, Sarah Holguin, MBA. B.S, Joe Vargas, M.S

Adhesion slides are widely preferred for IHC to aid in securing tissue sections to the slide and prevent reworks that could potentially postpone a patient diagnosis and drive-up costs in the lab. The cost of reworking a failed IHC slide due to poor tissue adhesion is estimated to be ~$80 per slide, considering the reagent cost and workload administration.1 Adhesion slides reinforce tissue adherence and integrity, minimizing the need to recut and restain the sample to ensure proper tissue morphological characteristics. Adhesion slides may also be used for H&E stains and special stains for added adhesion, but could retain excess reagent, or background staining, on the slide. In this study the differences in contact angle and in tissue adherence during microtomy were analyzed, investigation was done on whether different adhesion slides exhibit similar levels of background staining during histological staining procedures, and evaluation and comparison of the tissue adhesion properties of adhesion slide brands across different tissue types and applications was performed. After wide-ranging testing of adhesion slide characteristics, this study exhibited that not all adhesion slides are created equal. While water bath behavior showed to not be a relevant factor, there was considerable variation in background staining and tissue adhesion between slides. The results of this study suggested that it is important to determine what the needs are for your laboratory based on the types of staining done and tissue types used. It is also important to test adhesion slides to find the right slide or slides for your laboratory applications.