The plasma-thrombin method is commonly used to make cell blocks from fine-needle aspiration (FNA) samples but requires centrifugation. We describe a modification to this method that does not require centrifugation for use in resource-limited settings.
Pooled fresh plasma is aliquoted into 2-mL Eppendorf tubes and the FNA sample directly rinsed into the plasma. Two drops of reconstituted thrombin are added and gently mixed. A cell clot is transferred to a tissue bag, fixed in formalin, and processed. This method was applied to FNA samples from 44 patients presenting to the Mbarara University of Science and Technology FNA clinic.
The cell blocks were less cellular than the smears but contained adequate material to confirm morphologic impression or perform immunocytochemistry in 36 of 44 cases (82% adequacy rate).
The modified plasma-thrombin method is a reliable cell block preparation method that can be easily applied in resource-limited settings.