Perfecting the fine‐needle aspirate cell block

History of the Cell Block in CytopathologyThe cell block (CB) technique has been in use for more than a century.The first report of this technique was made by Bahrenburg in 1896. 1 He described a novel method that was applied to large quantity ascitic fluid in 2 patients, which enabled him to process the fluid into histologic sections.Dr. Bahrenburg's technique consisted of allowing the fluid to stand and clot spontaneously for 24 hours, followed by pouring off the supernatant fluid and allowing the sediment to be hardened by addition of alcohol to obtain a firm and hard tissue mass that was subsequently embedded in celloidin.The tissue block was then cut and stained similar to histologic sections.Following this report, various CB techniques have been developed over the years that vary in scope and the type of fixatives, processing, and embedding techniques used.Some of the most common techniques include inverted filter sedimentation, collodion bag, thrombin method, simple sedimentation, and Millipore filtration, among others.