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A good cell block preparation can be utilized for additional ancillary studies such as immunohistochemical stains, fluorescence in situ hybridization, and other molecular studies necessary for the diagnosis and treatment of the patients. Ancillary tests that are validated for formalin-fixed specimens may have to be revalidated for specimens that are fixed in alcohol. Alcohol-fixed specimens may have altered antigenicity which may render some of the tests falsely negative.

Different cell block preparation methods utilize different collection mediums for transportation and fixation of the specimen collected, for example methanol is used as a fixative for the automated Cellient cell block technique [19]. Other methods of cell block preparation are the clot and scrape method, BBC cell block fixative method, plasma thrombin cell block preparation, collodion bag cell block procedure, Shandon cytoblock method, HistoGel method, Tissue coagulum clot method, and Formalin or alcohol vapor method [19]. The clot and scrape method and formalin/alcohol vapor method are both inexpensive techniques but are reported to have variable quality and cellularity. The collodion method, although time consuming, has a good cellular yield, making it ideal for samples with scant cellularity. Collodion is admixed with an ether-based solvent; it must be handled in a laminar flow hood and stored in small volumes in a flameproof enclosure [20]. The Cellient automated system is time consuming and expensive but is great for small/scanty samples and provides a crisp cellular architecture. As it is fully automated, there is little chance of cross-contamination. It utilizes methanol as the fixative which could interfere with certain immunohistochemical stains. However, in a separate protocol formalin can be used as the fixative. The instrument can accommodate only one specimen block at a time, so high-volume labs may require multiple instruments. The HistoGel method is tedious but helps in the concentration of cells and provides good cellular preservation. The plasma thrombin method is an inexpensive and simple method and provides a clean background. The disadvantages of this technique include an inability to control clot formation and irregular distribution of cells within the pellet. Some thromboplastin agents contain epithelial cells that may interfere with the diagnosis and with the interpretation of ancillary studies [21].