Tissue decay begins immediately after removal from the body and particularly affects DNA and RNA. If molecular profiling is a consideration for a tissue specimen, it is essential that careful planning take place prior to the procedure to ensure that tissue will be collected, transported, and handled in a manner which will maximally preserve DNA and RNA.
There are three major considerations during initial tissue handling to minimize damage to DNA and RNA. Variables such as temperature, time of handling, and specimen size affect the rate of decay and should be managed to minimize damage.
Optimally, special fixatives may be used which both protect tissue morphology for histologic examination and preserve the molecular properties at the same time. As molecular methods of testing evolve, it may become necessary and more commonplace for "universal" fixatives (those which work well for both routine histology and molecular testing) to become part of routine tissue handling in clinical histopathology.