What is pathological diagnosis? Most patients do not know about pathological diagnosis, and even some hospital doctors do not know much about it. So, what is pathological diagnosis? A simple analogy is that it is the “Sherlock Holmes” of doctors. The pathologist first observes the general shape of the excised specimen and the human tissue cut off during surgery. Then the material is taken, i.e., the typical part of the lesion is cut, and after a series of technical treatments such as fixation and dehydration, the tissue is made into thin slices [about 3-4 microns} with a microtome, placed on slides, and then stained and other processes, and finally the characteristics of the lesion are observed under a microscope. Based on the cellular morphology and tissue structure of the lesion, a precise pathological diagnosis is made by combining clinical and other auxiliary means, such as electron microscopy, histochemistry, immunohistochemistry, DNA ploidy and molecular biology techniques.