Cytological preparations for molecular analysis: A review of technical procedures, advantages and limitations for referring samples for testing

Abstract

Minimally invasive procedures such as endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) must yield not only good quality and quantity of material for morphological assessment, but also an adequate sample for analysis of molecular markers to guide patients to appropriate targeted therapies. In this context, cytopathologists worldwide should be familiar with minimum requirements for refereeing cytological samples for testing. The present manuscript is a review with comprehensive description of the content of the workshop entitled Cytological preparations for molecular analysis: pre-analytical issues for EBUS TBNA, presented at the 40th European Congress of Cytopathology in Liverpool, UK. The present review emphasises the advantages and limitations of different types of cytology substrates used for molecular analysis such as archival smears, liquid-based preparations, archival cytospin preparations and FTA (Flinders Technology Associates) cards, as well as their technical requirements/features. These various types of cytological specimens can be successfully used for an extensive array of molecular studies, but the quality and quantity of extracted nucleic acids rely directly on adequate pre-analytical assessment of those samples. In this setting, cytopathologists must not only be familiar with the different types of specimens and associated technical procedures, but also correctly handle the material provided by minimally invasive procedures, ensuring that there is sufficient amount of material for a precise diagnosis and correct management of the patient through personalised care.

Diff-Quik Cytology Smears from Endobronchial Ultrasound Transbronchial Needle Aspiration Lymph Node Specimens as a Source of DNA for Next-Generation Sequencing Instead of Cell Blocks

“…Some previous studies have looked at workflow options for NGS [41-43]. One study of cytology samples [44] showed that from 207 FNA samples, there was overall NGS success in 79% of cases.…”

Preanalytic Variables and Tissue Stewardship for Reliable Next-Generation Sequencing (NGS) Clinical Analysis

“…Cytopathologists should therefore be familiar with different specimen types, associated technical procedures, and variables that can affect test results to correctly handle the material provided. 51,52 It is recommended that the validation of NGS-based testing incorporates nonecell-block cytology specimens and that a cytopathologist is consulted as an expert to inform validation and liaise between the molecular laboratory and biopsy team. 49,53 A key preanalytic requirement for reliable biomarker analysis is that tissue specimens are of sufficient quantity and quality to permit morphologic diagnosis as well as ancillary biomarker profiling.…”

TissueGrinder, a novel technology for rapid generation of patient-derived single cell suspensions from solid tumors by mechanical tissue dissociation

“…The combination of personalized medicine with the increasing availability of novel diagnostic technologies has enormously increased the demand for sufficient quantities of high-quality biological samples [3,[10][11][12][13][14][15][16][17][18]. Many personalized medicine approaches involving single cell sequencing or drug screening rely on cell isolation from biopsy or surgically resected tumor material [8,[19][20][21].…”