Sodium Alginate versus Plasma Thrombin Cell Blocks in Diagnostic Cytopathology: A Comparative Analysis.

BACKGROUND Cell blocks (CBs) are an essential adjunct in cytopathology practice. The aim of this study was to compare 2 techniques of CB preparation - plasma thrombin (PT) method with sodium alginate (SA) method for overall cellularity, morphological preservation, obscuring artefacts, immunocytochemistry (ICC), suitability for molecular analysis, and cost of preparation. DESIGN A total of 80 fine-needle aspirates from various sites and serous effusion samples were included. Of these cases, by random selection, 40 each were prepared by PT method and SA methods, respectively. The haematoxylin-eosin-stained sections from the formalin-fixed, paraffin-embedded CBs from both methods were evaluated in a blinded fashion by 2 cytopathologists and scored for cellularity, artefacts, and morphological preservation and analysed by χ2 test with Yates correction. We evaluated 6 cases from each method by ICC for a range of membrane, cytoplasmic and nuclear marker expression. DNA was extracted from four cases to evaluate their utility for molecular analysis. RESULTS CB sections from PT and SA techniques showed comparable cellularity and excellent cytomorphological preservation. Blue gel-like artefacts were common in the SA technique but did not interfere with morphological evaluation. ICC staining results were also similar. DNA yield and utility for PCR were also comparable. The SA-CB cost half that of PT-CB (USD 0.4 vs. USD 1). CONCLUSION SA technique of CB preparation is an excellent low-cost alternative to PT method for CB preparation.